Class 9 Life Science and Environment

Environment And Its Resources

Ecology And Ecological Organization

Life and Environment: The natural surroundings of an organism, which affect its life, by directly influencing its activities, is called an environment.

• The environment includes both physical and biological environments. The physical environment includes air, water, soil, temperature, light, etc. The biotic factors include plants, animals, viruses and microbes.
• On Earth, we have all the requisite elements of life like water, air, and soil. Naturally, this Earth is our sweet home.
• For a healthy and happy life, we have to build good surroundings, where we could live generation after generation.
• Water is necessary for quenching our thirst, air for breathing, and soil for the production of food and other essential materials.
• In the world, we have enough natural resources like forests, oils, minerals, coal wildlife and many others.

Over and above, we have enough sunlight a source of all energies and a favourable temperature that influences the growth and distribution of plants and animals and makes our living enjoyable.

• Environment denotes the total of physical (abiotic) and biological factors (biotic) that directly influence the survival, growth, development and reproduction of the organism.
• In the modern concept, the environment is the total of living and non-living things which exert influence on the living organisms present in a particular area.
• Plants, animals, air, water, soil, temperature and light are the basic and essential elements of the environment. The former two i.e. plants and animals, are biotic elements, whereas air, water, soil, temperature and light are abiotic elements.
• Environment plays a key role in making life i.e. life is solely and wholly dependent on the environment.

Concept Of Ecology

The place where living organisms live with their surroundings forms their environment.

• Both physical and biotic environment together forms an environment. Soil, water, air, etc. form the physical environment. Whereas the biotic environment is formed of plants and animals.
• Living organisms and the environment are interdependent.
• The branch of science which deals with the interrelationship between the living organism and the environment is known as ecology.
• Therefore ecology is the study of interactions between organisms and their environment including other organisms.
• German biologist E. Haeckel (1869), first proposed the term ecology, which is derived from the Greek word ‘Oikos’ meaning “dwelling place or house” and “logos” meaning “study”. In ecology interactions of organisms and their organizations are studied at the following levels.

Individual Level

Ecological interactions of organisms and their organizations are studied about a particular kind—Adaptation to light, humidity and temperature.

• Introduction: The different mineral salts such as calcium, potassium, magnesium, sulphur, oxygen, nitrogen, carbon dioxide, water, soil, etc. form the abiotic factors of the ecosystem. The producers i.e. green plants secure these substances from soil and air to prepare their foods. Some physical factors are light, humidity and temperature.
• Light: Life cannot exist without light. Light is an essential physical ecological factor for photosynthesis and the production of food. The wavelength, intensity and duration of light play an important role in photosynthesis.
• In plants: The various functions performed by plants like photosynthesis, transpiration, germination, action of enzymes, phototropic movements or formation of growth hormones, hormonal actions, tissue differentiation, flowering, water absorption, development of palisade, production of chlorophyll, number and position of chloroplastids, movement of stomata, formation of flowers, fruits are influenced by light. The plants undergo various forms of adaptations to obtain light.

For reference only: Pnotophilic plants depend on bright sunlight whereas photophobic plants prefer low light conditions. The formation of flower fruits and seeds is favoured by strong light.

• Photoperiodism influences the growth, flowering and fruiting of plants.
• short-day plants (SDP) flowers are produced when the duration of light is less than 12 hours e.g. Dahlia,
• In long-day plants (LDP) flowers are produced when the duration of light per day is more than 12 hours (Spinach).
• In day-neutral plants (DNP) (cotton)- plants grow in short or long day conditions and blue and UV rays of light influence the growth and development of plants. Development of tissues takes place under red light.

In animals: Light plays an important role in animals. Distribution, colour pigmentation and certain structures of terrestrial animals are affected by light.

• The reproductive activities of birds are influenced by light. Animals like cockroaches, moths, and bats are active during the night. Bees orient at an angle rather than flying towards or away from the sun. Locusts do not fly in cloudy conditions.
• Their migratory movement, colouration, and development of special structures are influenced by light.
• The producers in the marine environment are present only in areas where light is sufficient, the consumers (for example animals) depending on plants for food are present in large numbers in or near-surface layers of water.
• The low intensity of light forms the causal factor of bioluminescence in the sea.

Humidity: The water vapour content in the air is represented by humidity. The pressure. of water vapour at a particular temperature is called absolute humidity. Regulation of different activities and distribution of organisms depends on humidity.

• The form and structure of plants are influenced by humidity. Humidity affects the rate of transpiration and water relations in plants.
• Plants growing in humid regions show elongated stems with long internodes and thinner leaves.
• Relative humidity affects animals. Rain forests where the air is saturated by moisture form the habitat of many animals. Desert animals thrive under extremely dry conditions. Birds and mammals living in warm humid regions exhibit dark colours.
• Humidity controls locomotion, feeding, and reproduction in insects and spiders.
• In Lepisma saccharina (silverfish) reproduction takes place at 85 to 90 percent relative humidity. Death of young ones takes place when humidity falls below 70 per cent. Excess humidity hurts normal feeding and development. Humidity higher than 88 per cent causes death of tsetse fly. Under moist air conditions, silkworms do not pupate.

Temperature: Temperature, a measure of the intensity of heat (expressed as degrees either in Fahrenheit or Celsius scale) is an essential and changeable environmental factor. It influences all forms of life and acts as a limiting factor for the growth and distribution of plants and animals.

• The temperature values at the equator are maximum, gradually decreasing towards the poles.
• Temperature decreases progressively from plains to high altitudes. Altitude affects values of temperature. At the poles, the temperature is < 0°C whereas in tropical deserts during summer temperature rises above 50°C.

For reference only: The division of earth’s vegetation into zones like equatorial, tropical, coniferous, and alpine, depends on variations in temperature at different latitudes. Temperature exceeds 100°C in habitats like thermal springs and deep-sea hydrothermal vents.

1. Temperature influences vital activities of living organisms like metabolism, behaviour, reproduction, embryonic development and death. Temperature plays an important role in the activity of enzymes which in turn influences basal metabolism and physiological functions of organisms.
2. Organisms which can tolerate a wide range of temperatures i.e. huge fluctuations are called eurythermal examples. toad, wall lizard. Organisms which can tolerate a narrow range of temperatures are called stenothermal example fish, and snails.
3. The extent of geographical distribution of different species depends on their level of thermal tolerance. Plants are divided into four categories based on their heat-tolerating capacity

1. Megatherms: plants which can tolerate high temperatures throughout the year for example desert vegetation and tropical rain forests. Tropical plants require constant high temperatures for their maximum growth
2. Mesotherms: plants which can withstand high as well as low temperatures, for example, tropical deciduous forests, and aquatic plants.
3. Microtherms: plants growing in regions of low temperature, for example, mixed coniferous forests
4. Hekistotherms: plants growing in regions where the temperature is very low, examples of alpine vegetation. Alpine plants are adapted for short summer periods for flowering and fruiting. Plants receive energy from absorbed solar radiation and convection and they lose heat by radiation, convection and evapotranspiration.

Based On Temperature Control Animals Are Divided Into Three Groups:

1.  Poikilothermalor Ectothermicanimalsor Cold-blooded animals whose body temperature changes with a change in their environmental temperature example most invertebrates and vertebrates like fish and amphibia.
2. Homeothermic or Endothermic animals or Warm-blooded animals whose body temperature is independent of the temperature of their environment, for example, birds and mammals.
3. Heterotherms Animals with limited power of temperature regulation respond to extreme temperatures by aestivation and hibernation example some marsupials.

Know The Facts

• Hibernation: A state of inactivity shown by some animals during cold winter months to tide over unfavourable conditions, like scarcity of food and extremely cold weather. Physiological changes are lowering of blood pressure and body temperature, slowing down of heartbeat, pulse rate, metabolism and other vital processes. Animals under hibernation are dependent on fat reserves stored in their body. Examples of hibernating animals are hedgehogs, bats, amphibians, many fish, and reptiles. Cutaneous respiration is mainly shown in hibernating animals.
• Aestivation: Animals like lungfish show a state of inactivity during prolonged periods of drought or heat. At this phase, feeding, respiratory movements and other body activities slow down considerably.

Population Level

Population Level Definition: Population is the term given to a group of individuals of the same species inhabiting a particular geographic area at a given period. The total number of species in a specific natural habitat is called population density.

• This population density changes during a given period due to changes in some basic processes during a specific time. These basic processes are Natality, Mortality, Immigration and Emigration. Natality and Immigration result in an increase in population, whereas Mortality and Emigration result in a decrease in population.
• Population growth refers to an increase in the size of a population determined by the number of individuals added to the population and members of individuals lost from a population.

Population keeps changing with time, availability of food, predation pressure, and changes in weather conditions.

1. Natality or Birth Rate: Population increases with an increase in birth rate. It is an expression of the production of new individuals in the population during a given period thereby adding to the initial population density. Natality is the expression of the birth rate of individuals in unit time.
2. Mortality or Death Rate: Mortality is the expression of death or loss of individuals in a population during a given period. The rate of mortality may be expressed as the percentage of individuals dying within a particular time.
3. Migration: It is a process in which animals move from one habitat to another according to the seasons. It is of two types:

• Immigration: Immigration may be expressed as an increase in population-level clue to the entry of members or individuals of the same species from other areas into a particular area during a particular time. Entry of population from one place increases population size and density in the immigrant place.
• Emigration: Emigration is a form of population dispersion where the individuals of a population exhibit movement from their habitat to areas previously unoccupied by the members of the population. This prevents overcrowding of the habitat during the period considered. Emigration may occur for food, environmental factors, breeding behaviour, and for gaining opportunities for interbreeding with other populations. Population density increases when several births and the number of immigrants is more than the number of deaths and number of emigrants.

Community Level

Competition: A set of interacting populations is called a community a group of animals or plants living or growing in the same place. Possible types of interactions among them are stated below

• In such kind of population interaction, the two individuals or species compete for a limited resource. The individuals are affected adversely by one another in their search for food, shelter or other requirements for existence.
• Such competition between individuals of the same species is called intraspecific competition, and such competition between two or more species is called interspecific competition takes place. With changes in environmental conditions entry of new invaders takes place and a reduction in several existing ones may occur.

1. Intraspecific competition: Competition among the same species in a particular geographical area. for example. competition among tigers to catch deer in a forest.
2. Interspecific competition: Competition takes place between individuals of different species of the same community for food, space and other requirements which are limiting, each is affected by the pressure of the other. At times resources may not be limiting but the feeding capacity of a species may be reduced due to interference caused by other species, for example. various carnivores in a forest may compete with one another to catch common prey like deer.

For reference only: Goats When Introduced on Galapagos Island, the greater browsing efficiency of the goats nurses the extinction of the Abington tortoise within a decade.

• According to Gnusc’s principle or Competitive exclusion principle, two non-interbreeding species with identical ecological niches cannot occupy the same environment.
• The competitively inferior one will be eliminated eventually.

For reference only: In competitive release when a competitively superior species is removed experimentally, a species whose distribution is restricted to a small geographical area expands.

• Field experiments by Connell showed that the larger and superior barnacle ‘Bctlanus’ dominates the intertidal area excluding the smaller barnacle Chathamalus from that zone.
• Competition affects plants and herbivores more than the carnivores.
• Recent studies however show that species facing competition may co-exist by changing feeding time or behaviour. in their foraging activities.

Predation: In such population interaction energy fixed by plants is transferred to a higher trophic level. In such interaction between two species one captures and kills another. Species which capture are called predators and those that are caught are called prey. Predators help in energy transfer across trophic levels and keep the population of prey under control.

For reference only:

• With the Introduction Of exotic species in a particular area, they invade the area and spread very fast.
• Prickly pear cactus introduced in Australia multiplied rapidly prey.
• This in turn threatens the existence of predators which may become extinct due to a deficit of food.
• Defence mechanisms are adapted by some prey to protect themselves from predators. Insects and frogs camouflage themselves to escape from their predators.
• Some are poisonous or distasteful which keeps predators away from them.
• For example, the presence of a special chemical in the body of a Monarch butterfly keeps birds away from them.
• Insects feed on plant sap and other plant parts and herbivores are predators of plants.
• Plants are unable to move away from their predators so some of them show morphological and chemical defence mechanisms to keep away the herbivores.

For reference only: Thorns serve as defence organs in plants like Acacia and cactus. Some plants possess chemical substances which protect them from their predators. Herbivores consuming these plants turn sick and may die.

• The feeding and digestive processes of the herbivores are inhibited after the consumption of these toxic chemicals.
• A highly poisonous cardiac glycoside is present in the weed Calotropis which keeps away the herbivores.
• Plants producing alkaloids nicotine, caffeine, quinine, and strychnine, serve as defence mechanisms against their predators.

Parasitism:

Definition of Parasite: When an organism is unable to prepare its food and has to depend upon other host plants or animals to obtain food and shelter for its survival, causing harm to the host then it is called a parasite.

Explanation: In such kind of interaction one species (parasite) gains while the other (host) is harmed but not killed by the association. Parasite depends on hosts for food and shelter. Parasite benefits at the expense of hosts. Some being host-specific are dependent on a particular host species. They develop some mechanism to overcome the resistance developed by the host.

For reference only:

• Some Adaptive features of parasites are loss o nin essential sense organs development of organs for adhesion suckers to attach themselves to their absence of the digestive system increasing the ability to reproduce some parasites requires one or two vectors to complete their life cycle.
• Parasites are carried by mosquitoes serving as vectors. Parasites have harmful effects on the host. They may reduce the chances of survival of their hosts or adversely affect growth, reproduction and population density making them more vulnerable to their predators.

Different Types of Parasites :

1. Phytoparasite: Plant parasites for example, root nematodes, aphids, lac insects, stem borers, and wasps forming galls on plants like oats, and willows. Mites from Witches Broom in Hackberry.
2. Zooparasite: Animal parasite for example. Platyhelminthes, nematodes, arthropods.
3. Hyperparasite: Such parasites live on another parasite, for example, Plasmodium vivax, a protozoan is a hyperparasite on the female Anopheles mosquito which is a parasite of humans.
4. Temporary parasite: Parasites like mosquitoes and bugs suck blood from their hosts. For example, Leech (Hirudinaria)’ sucks the blood of cattle and man.
5. Permanent parasite: Entamoeba histolytica, certain Platyhelminthes, nematodes, and arthropods are examples of permanent parasites.
6. Ectoparasites: live on the external surface of host organisms for example lice on humans, ticks on dogs, copepods on marine fishes, louse (Pediculus) sucks blood spreading diseases like typhus, Rat fleas [Xenopsylla] Spreads germs of plague from rat to man. Cuscuta is a rootless leafless parasite on hedge plants.

• Endoparasites: live inside the host body. For example,
• Entamoeba histolytica: a protozoan living in the human intestine that causes amoeboic dysentery.
• Plasmodium vivax: a protozoan living in human blood causes malaria.

Co-Operation:

• In this case, two individuals work together to achieve something. Both the species are profitable but their close association is not compulsory. They can live equally without association, e.g. the invertebrate animal Sea Anemone remains attached to the shells of hermit crabs. In this aspect both the species are benefitted (Positive).
• Another good example is cited here. The crocodile bird (Pluvionus aegyptius) enters the open mouth of a crocodile to feed on the blood-sucking parasitic leeches which live there. Food is obtained by the bird and instead of this, the crocodile gets relief out of those parasites which causes harm to them. Hence both partners can live well without their association.

Summary Of Types Of Population Interaction :

Ecosystem Level

Ecosystem Definition: The ecosystem is the functional unit of ecology, where biotic and abiotic factors interact in such a manner that through which matter cycles and energy flows. The term ecosystem was first proposed by Tansley.

In the structural aspect: Name different Abiotic factors through a chart

From the functional point of view, the living organisms of the Ecosystem are divided into two components by Odum (1917) Example

Biotic factor:

• Autotrophic components: Those living organisms of a biotic community for the preparation Of their food depending on the environment for water, carbon dioxide and for fixation of light energy are regarded as autotrophic components. All chlorophyll-containing green plants come under this category.
• Heterotrophic components: Those living organisms utilise, and decompose the complex substances produced by autotrophic components as they can’t prepare their food matters due to lack of chlorophyll are called heterotrophic components. Except few plants, most animals come under this category as they are directly or indirectly dependent on autotrophic components for food.

Biotic components: Biotic components are the constituents of a community. Each biotic community comprises of

1. Producers
2. Consumers and
3. Decomposers.

1. Producers: The green autophytic plants are regarded as producers. They can synthesize carbohydrates, proteins, fats, etc, from certain inorganic constituents (C02/ H_,0, mineral salts, etc.) of the surrounding environment with the help of chlorophyll in the presence of sunlight.

The producers prepare their food matters through the process of photosynthesis which is as follows

Know the facts

1. The term ecosystem was first used by a Christian Scientist Tansiey in the year 1935.
2. German biologist E. Haeckel (1369) first proposed the term ecology.
3. The different components of an ecosystem are interdependent. The environment is a term taken as a whole which includes all the conditions in which an organism lives, for example, light, temperature, humidity, water and other organisms.

2. Consumers :

Consumers are of three kinds

1. Primary consumers
2. Secondary consumers and
3. Tertiary consumers.
   1. Primary consumers: The plant eaters are called primary consumers or first-order
      consumers. The minute animals in the upper level of water constitute zoo plankton example, Daphnia, and protozoa. The primary consumers in the lower level of water are called bottom forms e.g., arthropods, snails, small fishes, etc. Primary consumers of land are herbivorous animals, for example, grasshoppers, pigeons, rabbits, monkeys, deer, cows, etc.
   2. Secondary consumers: The carnivorous animals feeding on the primary consumers are called secondary consumers or second-order consumers, for example, spiders, toads, frogs, moles, etc.
   3. Tertiary consumers: The animals living on the secondary consumers are called tertiary consumers or third-order consumers, for example, tigers, lions, leopards, whales, sharks, hawks, eagles, etc.

3. Decomposers: It is also called reducers or microconsumers. Certain heterotrophic bacteria and fungi break down the complex compounds of dead protoplasm, absorb some of the decomposed products and may release certain simpler substances for further utilisation by the producers. These together form the decomposers.

Transformers: Certain bacteria comprise this class. They are capable of reducing simpler substances decomposed by decomposers to further simpler forms and return these to the environment. These are consumed by the different forms of producers.

• Plankton: It indicates any dead or living organism (plants or animals), that floats passively in water and which is more or less dependent on water currents or wind action for their movements.
• Phytoplankton and Zooplankton: Free floating minute plants mostly unicellular or multicellular and solitary or colonial algae constitute what is called phytoplankton (Gr. Phyto, plants; plankton, floating), e.g. Spirogyra, Nostoc. They are autophytes parasites or saprophytes. Whereas free floating minute animals are called zooplankton, (Gr. Zoon animal, plankton floating), e.g. small arthropods.

Functional Aspects:

Food Chain: Definition and Types:

Food Chain Definition: “The transfer of food energy from the source in plants through a series of organisms with repeated eating and being eaten is known as the food chain”—Odum. The food chain may be defined as the sequential arrangement of producers and consumers of a particular ecosystem according to the predator relationship where eating being eaten takes place. At each transfer, 80%-90% of potential energy is dissipated as heat.

• In an ecosystem, the producer-consumer arrangement represents a trophic structure; where each food level is a good chain is called a trophic level.
• Green plants occupy the producer level (first, trophic level), plant- -eaters from the level of primary consumers (second trophic level), the carnivores that feed the Food chain of insects and birds, on the plant eaters, occupy the secondary consumer level (third trophic level) and the secondary carnivores the tertiary consumer level (fourth trophic level).

Types Of Food Chains: There are three types of food chains: predator food chain, parasitic food chain and saprophytic or detrital food chain.

1. Predator food chain: A predator food chain starts from green plants and extends up to carnivores i.e., it includes consumers only. Here the size of the living organism gradually increases, but their number gradually diminishes.
   1. Predator food chain – Grass → Grasshopper → Frog → Snake →Eagle
2. Parasitic food chain: A parasitic food chain goes from larger (host) to smaller (parasite) animals.
   1. Parasitic food chain – Plant → Pig → Helminth
3. A saprophytic or detrital food chain: A saprophytic food chain goes from dead organisms or organic matter into microorganisms. Such food chains are interconnected with each other to form a food web.
   1. Saprophytic food chain – Dead animal → Maggot Frog →Snake→Peacock

Food Web:

Food Web Definition: In a particular ecosystem, several food chains overlap and interconnect to form an interlocking, interlinking and interdependent pattern of a network called a food web.

Explanation: The food web is formed of food chains of the same habitat which are interconnected to form complicated networks, forming a foundation of ecosystems. The interconnections and interdependency in the food web where the food chain operates simultaneously make it more fundamental than the food chain. Hence food web is more stable than a food chain. A food web is the real feeding relationship at the trophic level when one animal depends on many animals of different trophic levels as food.

Difference between Food chain and Food web

Answer the following :

1. What do you mean by phytoplankton?
2. What do you mean by zooplankton?
3. Mention the two main categories of components of the ecosystem.
4. Snake dragonfly, toad and grass arrange them according to the levels of the food chain.
5. Write the terrestrial organisms in a sequence who eats whom and ultimately form a chain of at least three steps.

Things to remember

1. The functional unit of ecology is the ecosystem.
2. The interaction of living organisms with biotic and abiotic components of the environment is known as an ecosystem.
3. Stratification is the vertical distribution of different species occupying different trophic levels of the ecosystem.

Energy-Flow Ik Ecosystem :

Explanation: In an ecosystem, energy flows in a definite fashion. The main source of energy is the sun. Green plants synthesize carbohydrates or other food materials by the process of photosynthesis within their body from C02 and water with the help of sunlight. Mineral salts are necessary for this purpose.

For reference only: The rest of the food energy is stored within the plant body. Different types of microorganisms act on the plant body after their death. The microorganism carries out metabolic activities at the expense of decomposed plant materials. As such CO₂, nitrogenous compounds, etc. evolve which may be further utilized by the existing plants.

• All animals are dependent upon plants for their food. The animals utilize a part of the food for respiration. CO₂ and water produced during the respiration of animals may again be taken up by the plants. Animals get rid of excess mineral salts and certain toxic organic compounds from their body as excretory products which may be further utilized by the plants.
• In the soil after the decomposition of dead animals by the microorganisms, several chemical substances are produced. The plants may utilize these chemical substances.
• Energy never goes back to its source. In other words, the radiating solar energy never returns to the sun.
• The transformation of energy takes place. Green plants capture the solar energy to synthesize food having potential energy stored within its chemical bonds. Such potential energy transforms into kinetic energy during respiration. A portion of kinetic energy is released as heat in the environment that subsequently passes into space.
• Earth receives energy from the sun and loses energy continuously in space, as a result, the total energy content remains the same.

In summary, stages of energy flow in the ecosystem can be explained as follows:

1. Source of energy: The Sun is the only source.of energy on earth.
2. Fixation of energy: Green plants perform photosynthesis when solar energy is fixed in the form of potential chemical energy in glucose molecules.
3. Transfer of energy: Through the food chain and food web energy is transferred from producer to consumer and decomposer.
4. Gradual decrease in energy transfer (10 cent law): Raymond Lindeman proposed that in any ecosystem during energy flow, approximately 10% of energy is transferred from one trophic level to another trophic level. Thus amount of “energy transfer” gradually decreases towards a higher trophic level.
5. Unidirectional flow of energy: Through the food chain and food web energy always flows from producer to primary consumer, then to secondary consumer and so on in a unidirectional manner.

For reference only:

Stages of energy flow: Now energy flow in the ecosystem takes place in three successive stages :

1. Acquisition of energy,
2. Uses of energy and
3. Unidirectional flow of energy.

Acquisition of energy: The source of energy in the ecosystem is solar radiation. 12-3 x 1022 calories of solar energy reach the earth each year. Of which a major part is reflected in the space due to the presence of clouds, smoke, and dust particles.

• According to German Scientist Rudolf Geiger, about 42% of solar energy is reflected in space due to the presence of clouds, dust particles, etc. in the atmosphere. 10% of the solar energy and ozone, oxygen, water vapour, carbonic acid, etc. are absorbed by the suspended solid particles in the air. In the daytime 48% of the solar energy falls on the earth.
• Some of the light energy is also reflected from the surface of the earth. The remaining light energy is entrapped by the chlorophyll present in the palisade and spongy parenchymatous cells of the mesophyll tissue of the leaf where photosynthesis takes place. As a result, light energy is transformed into kinetic energy which is stored as potential energy in the carbohydrate food matter.
• The primary production in the ecosystem is the production of glucose by the green plants, energy released during this time is called gross production. After respiration and other living processes, the energy left behind is termed net production or NP.

Uses of energy: In an ecosystem, the producers transform solar energy into chemical energy and later in the presence of water and carbon dioxide prepare carbohydrates.

• These plants are taken in by animals and thus potential energy is acquired by them. Again when the secondary consumers feed oh primary consumers they also acquire potential energy. Thus when tertiary consumers take in secondary consumers, we see a similar flow of potential energy to occur.
• Thus, the main source of energy for all animals is food. The amount of energy acquired from food is called gross energy intake and in short, denoted by the letter I.

• When energy flows through the different trophic levels of an ecosystem we can see that, some energy is dissipated as heat at each step which is of no use. In the year 1942, Raymond Lindemann formulated the law called the 10 per cent law.
• According to this law, about 10% of total energy is transmitted during energy flow through several trophic levels. That is why we notice a diminution in the amount of energy. Energy used up by a body to function properly is called respiratory energy (R).
• For example, about 100 kg of organic food present in the grass, will make 100 kg biomass in the case of herbivorous animals, and about kg 1 kg biomass in the case of carnivores.
• According to Lindemann’s 10% law, in a grassland ecosystem about 100 kg of grass would increase 10 kg of flesh in the body of a deer. If this deer is taken in by a tiger its flesh would help in increasing 1 kg of flesh in the body of the tiger. Thus a gradual diminution of energy is noticed.
• The formed energy is spent in digestion, metabolism and performing other physiological functions by an animal. Some energy is also liberated as heat and thus lost to the surroundings.

Energy Flow Is unidirectional:

Producers obtain their light energy from the solar energy. This light energy once entrapped by the chlorophyll cannot retrace its path but is given out to the surroundings. Thus, along the trophic level energy gets transmitted step by step but once given out it cannot follow its way back. Thus the energy flow is unidirectional.

• Source of energy of ecosystem Solar energy of the sun.
• Source of energy of living organisms Food.
• Unit of ecology Ecosystem.

Nutrient Cycle:

Nutrient Cycle Introduction: The cyclical movements of the chemical elements i.e. nutrient cycling of the biosphere between the living organism and the environment is called the bio-geochemical cycle. The earth is made up of soil, water, air, and millions of living organisms.

• A continuous exchange of materials and energy takes place between and within these two world. These exchanges occur in cycles, which involve a continuous circulation of substances between organisms and their physical environment.
• Substances such as oxygen, carbon dioxide, water and minerals are constantly absorbed by organisms, but as soon as these substances are lost from the physical world they are replaced by natural processes. There is a balance of nature in which losses equal replacements and in which materials are used and reused over and over again.
• Nearly 30 to 40 elements are required for the proper growth and development of living organisms. The most important of these are C, H, 0, P, K, N, S, Ca, Mg, Fe, B, Zn, Cl, Mo, I and F.

Nutrient Cycling Definition: The principal chemical elements of the biosphere flow from the abiotic to the biotic components and back to the non-living components again in a more or less cyclical manner, forming the bio-geochemical cycle. That is also called nutrient cycling.

Types of bio-geochemical cycles: There are three types the gaseous cycle (Carbon cycle, Oxygen cycle), the sedimentary cycle (Phosphorus cycle, Sulphur cycle) and the hydrological cycle (Water cycle).

Natural Resources And Its Sustainable Use Forest

1. Use: Forest functions: A forest in general may be defined as an area set aside for the production of timber, fuel, and bamboo and the forest produces a variety of products of commercial and industrial value or is maintained under woody vegetation for certain indirect benefits which it provides e.g. climate, protective and social functions. The ecological balance of nature is maintained by the forest.
2. Watershed protection: In this case, a forest helps to protect an area of land that separates water flowing to different rivers, basins or seas i.e. high-raised areas of good rainfall.
3. Atmospheric regulation: Forests influence the temperature of a place. The summer days are cooler and winter days are warmer due to the dense canopy which prevents re-radiation of heat absorbed during the daytime. Forests influence humidity by causing obstruction to wind and keeping air more moist. Water escaping from plants through the transpiration process remains in the air due to the slow movement of air. The litter and humus present in the forest soil provide the insulating effect. The rain-bearing winds cause more precipitation due to forests. Leaves of trees in forests show more condensation of moisture and fog drip. Solar radiation, temperature, wind, and humidity are influenced by forests.
4. Erosion control: In forests, the dense canopy formed by branches and leaves of trees prevents the water from reaching the earth with force. The litter and humus present in the forest floor absorb the water. The soil rich in organic matter is porous and permeable. It serves as a natural filtering agent and allows storage of water. Forest soil absorbs more water from melting snow. Forests check soil erosion caused by water. Trees acting as a wind break and shelter belts reduce the removal of fertile topsoil. The roots of trees are great soil binders and. play an important role in controlling erosion.
5. Local use: Tree branches are used for building commercial and industrial structures. Newspaper, sports equipment furniture are forest products. Pulpwood, poles, and railway sleepers are made from trees. Cattle grazing is done to a large extent. Rural people earn their livelihood by selling non-timber forest products. Medicinal plants, gums, resins, and edible fungi are forest products. Forests provide fuel and wood for energy.
6. Productive use: Forests provide several products such as timber, firewood, fruits and seeds, clothes, furniture, medicine, house building materials, etc.
   Forest vegetation prevents excessive stream temperatures by shading the courses of water which is very beneficial for fish life. Forests also help to create clean and clear streams which are very necessary for the fish life to survive in that condition.
7. Protection of wildlife: Wild animals find their natural habitat in dense forests. Thus forest helps in wildlife conservation.

Cause Of Deforestation And Consequences

Deforestation is the destruction of forests leading to non-forested areas.

For reference only:

Importance of forest: Forests are natural resources for fuel, timber, paper, medicinal plants, fodder, water yield, animal products, etc. They maintain the level of rainfall, by recycling moisture into the atmosphere by transpiration which falls back as rain. Trees conserve this rainwater. Forests help to check flood, and soil erosion and serve as an important habitat for wildlife.

• The tropical rain forests, the most productive type of forests have decreased to about 40 per cent and temperate forests to about 1 per cent. In India, about 30 per cent of land was covered by forests at the beginning of the 20^th century. However, it has reduced by about 19-4 per cent by the year 1999.
• In India, areas under dense forests to less than two-thirds of the existing forests and the rest are open degraded forests. National Forest Policy (1988) of India recommends an optimum 33 per cent forest area for the plains and about 67 per cent forest cover for the hills.

Causes of deforestation:

Some of the causes of deforestation are

1. Population explosion i.e. sudden increase in number.
2. Indiscriminate deforestation by man for agricultural land, cattle ranching, construction of dams, mining, construction of roadways and rail tracks.
3. Large-scale felling of trees to meet increased demand for timber, fuel wood, and paper.
4. Forest fires destroy trees and animal life.
5. Pests destroy trees by eating leaves and boring into shoots.
6. Forests are damaged by storms and snow.
7. Jhum or Shifting cultivation involves the burning of trees, ashes are used as fertiliser and the land is used for farming or purpose for cattle grazing. –
8. Water reservoirs constructed across the streams are used for generating power or prevention of floods.
9. Over-exploitation of land resources.

Consequences or effects of deforestation :

1. Decrease in groundwater.
2. Increase in soil erosion, water and wind erosion v.
3. Frequent floods and droughts destroy large numbers of trees.
4. CO₂ consumption and O₂ production were affected adversely.
5. Loss of genetic resources.
6. Increasing incidents of landslides and avalanches.
7. Changes in the pattern of rain.
8. Changes in climatic conditions in deforested areas i.e. global warming.
9. Loss of biodiversity due to deforestation.
10. Deterioration in quality of life of weaker section of people dwelling in forests.
11. Flash floods.
12. Global warming.
13. Soil erosion.
14. Due to cyclone, a natural calamity.
15. Siltation
16. Decrease in the quantity of timber.
17. Decrease in the quantity of fuel wood.
18. The uprooting of plants and loss of livelihood of indigenous people.

Things To Remember

Afforestation: It is a process of planting trees in an area of land to form a forest. The main objectives of afforestation are to increase the protective and productive outputs.

Water

Introduction: Water is a colourless, odourless liquid which freezes at 0°C and boils at 100°C. It is a compound of hydrogen and oxygen (H20). This liquid possesses some mass, has no shape and size, and exerts pressure in all directions of the container.

• Water is necessary to maintain life. Life cannot survive without water. Water helps organisms to grow and survive and allows easy penetration of light. Rain and snow are the primary sources of fresh water required by living organisms.
• Water is a vital natural resource, which is essential for multiple purposes. Its many uses include drinking and other domestic uses, industrial cooling, power generation, irrigation (agriculture), navigation (transportation) and waste disposal.
• Water is indeed a most essential commodity for human consumption and without it, no life can exist.
• It is one of the most important vital substances in the biosphere which is required for the various metabolic activities of living beings.
• Water is also required in industries for power generation, navigation and disposal of sewage and industrial waste.
• This water is synonymous with life and is gifted with unusual physio-chemical properties.

Use Of Water

• Drinking: Water which is fit for drinking is called potable water. Potable water is clear, colourless, odourless, free from harmful chemicals and coliform bacteria and contains enough amount of dissolved oxygen and no floating impurities. Natural hard water, due to the presence of dissolved salts imparts a refreshing taste is conducive to health and serves the purpose of drinking water.
• Agriculture: Agriculture is, in fact, a form of applied Biology.

For reference only: As we have discussed earlier, every living thing exists in inter-relations with other living things in some form or other, as well as with the surrounding physical conditions.

• The earthworm burrows the soil as a ‘natural tiller’ which helps to aerate and enrich the soil by keeping it permeable to water, the insects which pollinate the crop plant and the bacteria of putrefaction which restore nutrients to the soil. These are then, as much a part of agriculture as special crops grown.
• Agriculture, in reality, is largely the result of man’s taking advantage of these inter-relations of soil, climate and natural inhabitants to select those particular combinations that meet his requirements.
• Thus, to provide necessary food man depends entirely on green plants, which alone can captivate solar energy through which proteins, fats and carbohydrates are prepared.
• Irrigation is to supply water to land for the cultivation of crop plants. Water requirements for irrigation are by far the highest among various uses of fresh water.

For reference only: The amount of water required for irrigation purposes varies with the climate of the. region and the type of crops that are to be raised.

• Surface waters used for irrigation may be diverted through canals which afford gravity-aided flows to the irrigation area. Where the lands to be irrigated lie above the river, lift irrigation may be required.
• The total quantity of water used for irrigation is rather large. According to an estimate, about 41% of all the water used in the USA is for irrigation.
• It is estimated that nearly 3,500 litres of water per person per day are used just for irrigation.
• This quantity is several times higher than the average domestic demand.
• Estimates show that for obtaining 1 kg each of wheat, rice, meat and milk about 600, 2,000 25,000 and 400 litres of water are required, respectively.

Industry: Industry uses more water than any other commodity.

For reference only: According to estimates, more than 630 billion litres of water is consumed per day by industry in the USA. One ton of steel making consumes about 3,00,000 litres of water. For making an average automobile, about 4,50,000 litres of water is needed.

• Most of the water used by industry is for cooling and processing. For. example, water cools the hot gases produced in refining oil and hot steel in steel mills. Industry is very dependent on adequate water supplies. The enormous demand that industry has for water is indicated by the water requirement of some key industrial processes.
• The quantities of water used by industry vary widely. Major water users are steel, pulp and paper, textiles, chemicals and petroleum refining; they account for nearly 80 per cent of industrial water demand. Accurate projected requirements are not easily available for various industries in India.
• With a growing population, the demand for freshwater is steadily increasing in India, but as with all other resources, there is a limit to fresh water supply. In addition, the availability of high-quality water is dwindling because of misuse, waste and pollution.

Use of Water For Various Other Purposes:

1. Used for daily household work like cooking, washing, bathing, cleansing, cleaning, etc.
2. Used in industries.
3. Used in chemical laboratories as solvents.
4. Used for performing biochemical reactions.
5. Used in the production of medicines.
6. Used for navigation purposes.
7. Used in photography.
8. Used in textile and paper industries.
9. Used in aquaculture and pisciculture.
10. Water can dissolve gases like carbon dioxide and oxygen.
11. Over-utilisation of Water And Water Scarcity

For reference only:

• Scarcity of water results from a lack of sufficient water resources to meet the demands of water users within a region. Groundwater forms the biggest reservoir of fresh water on earth and is used for agricultural, industrial and domestic purposes.
• Water is used for drinking, bathing, washing, irrigation, industry, cooling, construction work, sewage disposal, and disposal of industrial effluents. Water influences the ecosystem by affecting climate, erosion and providing life for biodiversity.
• Excessive use of groundwater may cause a fall in the water table. When the amount of water used exceeds than amount of water obtained through precipitation, a deficit in the water supply takes place. Depletion of groundwater levels may lead to contamination of drinking water. Stream flows and lake levels are also affected. Reduction in stream flow intrusion of salt water and variation in estuarine salinities results from overuse of water.
• When freshwater resources are overutilized aquatic ecosystems both marine and fresh v/ater are destroyed, several species become extinct, and water-related diseases spread out. Such problems arise with the rise in human population.
• Proper planning and management are required to sustain ecosystems and maintain human health. Water scarcity may indirectly lead to a shortage of food due to a reduction in agricultural productivity and poor living conditions. Overuse of v/ater in an area may cause a change in the climate condition of that area. Desertification may occur.
• Water needs to be conserved. Wide-scale adoption of lav/ for irrigation systems like drip, micro sprinklers and automation is used in agricultural lands to decrease v/ater requirement.
• In domestic and urban sectors conservation of water is focussed on proper monitoring of municipal water systems—their repair and control whenever necessary. All citizens should be aware of proper use of water and avoid misuse of this natural resource. Public water conservation campaigns are necessary to awareness of water scarcity.
• Our planet, earth, has a fixed amount of water. The distribution of vectors varies from place to place. The amount of fresh water available is sufficient to meet our needs. Despite that, there is a global shortage of water in usable form. This is because v/e don’t use water judiciously and a lot of water remains unutilised or wasted.
• Water from the atmosphere reaches the earth’s surface through rainfall and from the earth’s surface, it reaches the atmosphere through evaporation and transpiration. This continuous exchange of water from the earth to the atmosphere and vice versa is maintained by nature, through the water cycle.

Causes of Scarcity of water :

1. Scarcity of water due to drought: Water scarcity occurs sometimes due to severe drought conditions. It is due to a lack of rainfall for a sufficient duration. Severe droughts, result in a reduction in ground water level, and the destruction of grasslands, pastures and crops.
2. Scarcity of water due to misutilisation of water: Improper utilization and distribution of water and deterioration of water quality cause water scarcity. This problem can be solved by recycling water at the local level.
3. Scarcity of water by other causes: The other reasons for the scarcity of water are the depth of water is decreased due to soil erosion and most of the Water bodies are filled up for human habitats. Water also getting polluted due to several reasons.-Further, deforestation results in less rainfall.

• • Hence water scarcity causes great problems to the living world. It affects the lives of humans, aquatic plants, animals and microbes due to which the ecosystem is going to be unbalanced causing hazards for human beings.

Water conservation: To meet the water scarcity problem water has to be conserved by the following methods.

1. Proper distribution and utilization of water.
2. Proper drainage methods are to be implemented.
3. Proper storage of water by digging ponds and tanks and building dams and irrigation canals.
4. Proper maintenance of ponds, pools, jheels, lakes, etc.
5. Floods should be controlled by constructing dams.

Reasons For Water Scarcity :

1. Depletion and deterioration of available and usable water resources.
2. Droughts and floods.
3. Increased pollution.
4. Increased human demand for water.
5. Overuse of water.
6. Lack of means to provide water to meet household, industrial, agricultural and environmental needs.
7. Increase in human population.
8. Lack of access to safe drinking water.

Rainwater Harvesting

• The basic source of water is rainfall. Rainwater can provide a solution when water quality falls or varies during the rainy season.
• To store and obtain water according to necessity dams, lakes, and canals were made.
• The rainwater harvesting technique is used to store rainwater in special water harvesting structures like wells, pits, dams, lagoons, etc.
• This form of harvesting rainfall benefits all particularly in. areas where rainfall is scarce.
• A severe shortage of water may occur. Growing trees in watershed areas increases the retention of rainwater and protects soil from erosion.
• Rooftop rainwater harvesting forms one of the best methods of harvesting rainwater.
• This is a simple and low-cost technique requiring minimum knowledge.

The rainwater harvesting system consists of three basic components:

1. Roof surface for collection of rainwater,
2. gutters and drain pipes are required for the transport of water from the roof to the storage reservoir,
3. Storage tanks or reservoirs are used to store water.
4. Rainwater from the rooftop is drained into a storage pit or tank and stored for future use.
5. This water may be used for irrigation or domestic purposes.
6. Water from the storage tank when passed through the filter may be used as drinking water.
7. System of harvesting of water in rooftops.

• The advantage of rainwater harvesting on rooftops is a simple and low-cost technique. Such a system can be trained well.
• The water obtained is of good quality. Such a system causes no harm to the environment. Rainwater harvesting has several advantages.
• It reduces runoff water and checks soil erosion, controls flood supply water during dry months. Rainwater helps increase the level of the water table.
• Water harvesting is a necessity in areas which are arid and semi-arid with scanty rainfall.

Disadvantages of rainwater harvesting:

• Water supply problems may arise during droughts.
• The supply of water depends on the amount of rainfall.
• In the rooftop form of rainwater harvesting and dams, regular inspection, cleaning and repairing are required.
• In the rooftop form of water harvesting rainwater may be contaminated with air pollutants, animal or bird droppings, insects, etc.

Case Study

• A chronic shortage of water has been going on in Israel for years due to drought leading to a water crisis in recent years. The deficit in renewable water resources caused the depletion of potable water resources.
• Due to the deficit of the qualitative deterioration of drinking pure water resources which become either of brackish quality (slightly salty) or otherwise become polluted causing a problem in solving the severity of the present crisis, whereby water supply was drastically minimised.
• Increased population and rise in standard of living caused overutilization of water resources. The agricultural sector suffered due to this crisis.
  Understanding the relative importance of changes long-term perspective institutional and operational is required in this connection to stabilize the situation.

Water Scarcity Problem Australia (A case study)

• Water scarcity is the lack of sufficient available water resources to meet the demands of water usage within a region. It involves water stress, water shortage and water crisis.
• In Australia, climatic change and variability show an abundance of water in the tropical north with fewer inhabitants and a relative scarcity of water in the densely populated temperate south.
• In the south rainfall is less and the governance system is poor.
• Overuse of surface and groundwater supplies and increased requirement of water in fields of irrigation, domestic purposes, and mining, leads to scarcity of water.
• The population and agricultural activities are concentrated where the resources of water are limited. A balance between the extraction of water for irrigation and maintenance of environmental flow in rivers to required.
• The health of rivers, groundwater, wet: lands, flood plains and estuaries depends on land management factors like drainage, nutrients, and chemical pesticide loading.

Investment in plantation, farm forestry and general revegetation may form a landscape with the potential to treat the cause of land and water degradation problems. The Council of Australian Governments (CoAG) response to this water issue is developing an intergovernmental agreement called the National Water Initiative (NWI).

• The objective is to increase productivity and efficiency of water use, better service to rural and urban communities, ensure the health of the river and groundwater system of planned trading and sustainable use of water, and the inclusion of reform processes for improving water use efficiency and productivity.
• Reallocation of water between irrigation activities from irrigation to river and groundwater flow and some movement of water from irrigation to urban use.
• Recycling and reuse of water is essential. Water productivity may be increased by growing more food with less water.
• Shifting of water use by trading from low-value crops to high-value crops.
• Important causes of water scarcity are population expansion, urbanisation and the growing need for sewage, cleaning, manufacture, and pollution contributing to a reduction in water quality. Deforestation and destruction of vegetation cause drying of soil and climatic changes.

Know the Facts

A list of countries with populations affected due to water scarcity is given below :

• SUDAN-12-3 million
• VENEZUELA-5-0 million
• ETHIOPIA-2-7 million
• TUNISIA 2-1 million
• CUBA 1-3 million

Food Source

1. Agriculture: Agriculture, as a whole, is a form of applied biology; since every living thing exists in complex inter-relations with other living things. Modern man, unlike his primitive ancestors, does not depend upon fishing and hunting, lie cultivates plants arid rears fish as well as cattle and other domestic animals to get food and other necessities of life. Better and reproductive varieties of crop plants, such as rice, wheat, jute, sugar cane, pulses and cotton are now bred experimentally. Disease-resistant grains are raised and seeds are vernalised by special treatments to yield the crop before the usual time of harvesting.

2. Horticulture: The art or practice of cultivating and changing gardens. It deals with the science of growing flowers, fruits, vegetables, and ornamental plants. Improvement of crop plants both qualitatively and quantitatively is not possible without the knowledge of biology. Hybridisation techniques and modern methods of cultivation are being used for the production of new varieties of economically important plants. The use of disease-resisting varieties increases the production.

• Application of breeding techniques resulted in the improvement of livestock (cattle, sheep, poultry) with an improved yield of milk, meat, wool arid eggs. Improved and productive varieties are raised through selective breeding.
• Plant breeding plays an important role in the improvement of crop plants. Increased yield of cereals like wheat, paddy, Jowan, Bazra, and Maize, and improvement in quality and yield of legumes like pea, gram, and bean, were possible by applying various techniques of plant breeding. This resulted in increased production and helped to minimise the problem of food scarcity. This period in the middle of the 1960s was referred to as the Green Revolution. Plant breeding systems developed high-yielding disease-resistant varieties for enhancing the production of food.

3. Animal husbandry: The World is facing an acute shortage of foodstuff due to the very high rate of increasing human population. Different animal sources are utilized for enhanced food production. These include poultry, dairy firm management and animal breeding. The techniques of embryo transfer, tissue culture, induced breeding, etc. are also practised.

• Live stock includes domesticated farm animals such as cows, buffalo, sheep, etc. reared to get meat and milk. Meat animals are cows, buffaloes, goats and sheep. The milk animals include cows, buffaloes, etc.
• Besides meat and milk, some animals are domesticated on farms for multiple purposes. These animals include horses, camels, bulls, deer, yaks and poultry birds. Birds like chickens, turkeys, ducks and geese are known as poultry birds which are reared for meat and egg.
• Fisheries also provide an important source of animal food, concerned with rearing, catching and selling fish, molluscs (shellfish and crustaceans (prawns, crabs, etc.). The practice of apiculture beekeeping is another source of food as honey.

Role of animal husbandry in human welfare: Animal husbandry can be used to obtain a lot of benefits for mankind which are as follows

• Dairy products: Milk and other dairy products such as yoghurt, cheese, paneer, butter, ice cream, etc. could be obtained.
• Meat: The demand for protein is mainly covered by cattle and other animals.
• Land management: Grazing by live stocks can be used to control the growth of weeds
  in the agricultural field.
• Labour: Horses, donkeys, yaks, etc. can be used as mechanical carriers.
• Fibre: Sheep provides fur or wool for the textile industry.
• Fertilizer: Cow dung can be used as manure for the crop field. The blood and bones of animals also used as fertilizer
• Fishery: Fish can supply us with different types of easily digestible animal protein on one hand, and on the other, it may serve as a good source of nutritive and palatable food. Besides different types of vitamins and minerals are also present in fish. It is with an eye to the above that the entire world is earnestly trying to develop and improve pisciculture and increase its fish production.

Fisheries provide an important source of animal food, concerned with rearing, catching and selling fish, molluscs (shellfish) and crustaceans (prawns, crabs, etc).

Alternate food sources: Food energy is provided by cereal grain forming staple foods example maize, wheat, and rice. Bacteria and fungi are used for preparing bread, alcoholic drinks, cheese, pickles, yoghurt, etc. Bluegreen alga Spirulina is also used as food.

• Plant seeds form a good source of food for animals and humans. For example, cereals (Maize, rice, wheat) legumes (peas, beans, lentils) and nuts.
• Oil is produced from oilseeds of sunflower, rape seed, sesame. Fruits eaten as vegetables are tomatoes, pumpkins, eggplants, etc. Potatoes, carrots (root vegetables), onion (bulb), spinach and lettuce (leaf vegetables) bamboo shoots (stem vegetables), and broccoli (inflorescence vegetable) are used as food.
• Animal sources of food are meat (muscle or organ of animals taken as food). Milk and dairy products formed by processing it (cheese, butter) are consumed as food. Honey produced by bees, and eggs laid by birds, are latten as food. Several organisations deal with agroecosystem soil fertility and biodiversity.
• Fungi used as food are mushrooms like Agaricus campestris, A bisporus, and ‘morels’ (Morchella esculenta). Some species under the genus Tuber (called truffles) are used as food. Pleurotus are sold as fresh mushrooms. Lycoperdin sp (puffball) are edible fungus. ‘Sufu’ a food is produced from Mucor. Saccharomyces cerevisiae (yeast) is used to produce yeast cake.

Some edible forms of algae are Laminaria, Alaria, Sargassum, Porphyra, Ulva, Chlorella, Chondrus, and Rhodymania, stipes and blades of seaweeds are used as food. Red alga Porphyra tenera is an edible seaweed, rich in protein, carbohydrates, and vitamins A, B, and C. ‘Kombu’ a food in Japan is prepared from Laminaria (a seaweed). Diatoms are also used as food. Brown alga (Sargassum) is also used as food.

• Bryophytes like mosses (for example Polytrichum ) provide food for herbivorous mammals, birds and other animals.
• The stalks and leaves of the Pteridophytic plants like Marsilea, Dryopteris, and Pteris. etc. are used as vegetables, especially during the scarcity of food.
• The seeds and young shoots of Cycas, a gymnosperm taken as food. The seeds of Pinus gerardiana, popularly known as chilgoza, can be taken as food after roasting. Gnetum ula seeds are also edible.

World Food Problem (case study) And Its Effect: Food problems arise from the lack of effective production of food required by people. The food problem is caused due to

1. slow down the yielding rate of the main cereal staple,
2. Damage caused to the environment
3. Resistance to pesticides
4. Higher food prices
5. Increased population
6. Distribution of food and individual access to food
7. Increasing urbanization
8. Intensive farming and irrigation system.

Priority should be given by several organisations to agricultural research and investments to increase agricultural productivity and production.

• Research should be planned in a way that the changing geographical and socio-economic characteristics of hunger are taken into account along with the perception of malnutrition-related problems by poor people.
• One of the serious earliest food scarcity in the form of famine faced by the people of the then Bengal before partition caused the death of a good number of people; which is stated below.
• Famine broke out in 1776. Many people died. The famine affected Bengal mostly. At that time Capital of Bengal was Murshidabad. Bengal was connected with Bihar and Orissa. In Bengal, this famine is popularly known as “Chiattarer Mannahtar”.

Famine and Food Insecurity in Ethiopia A Case Study: Ethiopia, the second most populous country in Sub-Saharan Africa has a population of about 75 million people. With a tropical monsoon climate and highly erratic rainfall, Ethiopia shows drought conditions.

• Agriculture is the primary source of livelihood and farmers rely on technologies which are traditional for producing yield mainly used for consumption.
• Farmers used local seeds from previous harvests. Limited use of chemical fertilizers, and obsolete tillage practices with efficient tillage tools were reasons behind low productivity.
• Ethiopia experienced famines of which the worst one took place between 1983-1985. The cause behind the famine was the failure of rainfall and the loss of livestock.
• Many people were affected and many died. The famine had long-term effects on the poor who sold their assets for their survival and had to face future crises.
• In 2002, there was another famine as an increase in production and lowering of prices led to food insecurity.
• The government of Ethiopia reached out to the international community for assistance.
• Though the food was available in the domestic market, the government did not have the money to buy this food for redistribution.
• Soil infertility due to erosion adversely affected agricultural productivity.
• Market failures resulted from a lack of access to modern transport by the majority of the rural people. They were unable to reach grain markets in the major production zones.
• Restriction from access to market information leads to market failures.
• Lack of specialization of wholesalers and low levels of commercial processing, rapid population growth were important causes of famine.
• Too small landholdings, lack of potable water. Inadequate incomes of farmers due to low agricultural productivity and lack of economic incentives caused hunger, malnutrition and disease among the poor farmers.

Energy Use

The capacity to do work is called energy. All forms of energy are mutually convertible one into another. The quantity of work done in the process of transfer is a measure of energy. Therefore, work units are commonly used as energy units.

Growing energy needs: One of the factors playing an important role in the process of economic growth of a nation is energy. The development of power resources in an organised manner results in the industrial development of a country.

• The requirement of energy is indispensable in the fields of agriculture, transport, business and domestic purposes. Electricity is used for various purposes and its wide range of applications in economic development in modern times shows the material advancement of a country.
• Economic growth depends on energy which is the ability or capacity to do work. The different forms of energy in use are electrical energy thermal energy, light energy, mechanical energy, chemical energy, etc.
• In SI units energy is measured in joules. The range of energy consumption in developed countries ranges from 5 to 11 kw, whereas the range varies between 1 to 1-5 kw in developing countries.

Uses of energy: The economic growth of a nation depends on energy which is indispensable in agriculture, transport, business and domestic areas in the form of electric energy, thermal energy, and light mechanical chemical energy.

1. A Building uses less healing and cooling energy to achieve and maintain a comfortable temperature when the rooms are insulated.
2. The use of fluorescent lights and skylights lessens the energy requirement for attaining the same illumination level. When compared to traditional incandescent lights.
3. Improved energy efficiency will reduce the world’s energy needs and reduce carbon dioxide emissions.
4. Energy is required in industries, transport, commerce telecommunication, household and industrial sectors.

Wastage of energy Or Energy conservation in daily life :

1. Electric lights should not be used during the day when there is natural light. Maximum use of daylight is necessary.
2. When short distances are involved walking is the best way. It saves petrol on the one hand and provides good exercise on the other hand.
3. Papers must be reused.
4. Polythene bags should not be used. The use of cloth bags and paper bags is a better option.
5. The use of solar heaters saves energy. ‘
6. Planting of trees ensures the purification of air.
7. Turning off unnecessary lights.
8. Improving lighting maintenance.
9. The use of insulating glass, insulated hot water pipes; and storage tanks saves energy.
10. Selection of refrigerator and freezer sizes according to family’s needs. Larger ones require more energy.
11. During cooking, pots and pans with flat bottoms need to be used. Pressure cookers to be used.
12. Air filters on exhaust fans need to be cleaned for better performance.
13. Turning off iron minutes before finishing ironing and ironing the clothes with the heat remaining in the iron.
14. The oven door should not be opened frequently while in use, as a considerable amount of heat escapes each time the door is open.
15. Avoid opening the door of the refrigerator now and then as the compressor has to run a bit longer to replace the cool air that spills out for it.
16. Wattages of incandescent light bulbs must be checked. The use of lower-wattage bulbs saves energy. The use of fluorescent lamps produces about four times as much light per watt as incandescent bulbs.

The most effective way to save energy is to improve operations and maintenance.

• Nowadays, alternative sources of energy have been discovered and are used in many places.
• For example, solar energy, solar batteries, solar cars; use of windmills; hydroelectric power etc.

• Life And Its Diversity Notes
• Levels Of Organization Of Life Notes
• Physiological Processes Of Life Notes
• Biology And Human Welfare Notes

Biology And Human Welfare Immunity And Human Diseases

Concept Of Immunity

The human body is subjected to a variety of harmful pathogens and foreign substances (antigens) from air, water, soil, food, etc.

• Our body has a mechanism of resistance to protect ourselves against those pathogens.
• This branch of science which deals with the responses of the body against antigens is called immunology.

Immunity: The ability of an organism to resist the harmful effects of a foreign protein or any antigen and thus to fight against diseases by producing immune bodies or antibodies is called immunity, in other words, immunity is the natural protective system of the body against different antigens.

• Every day our body is exposed to a large number of infectious agents but only a few of them may result in disease.
• Why? Because our body can fight against the disease-causing agents this ability is known as immunity.

Antigen: Any foreign, harmful, toxic chemical substance when introduced into the body, causes the body to produce specific antibodies is called an antigen. A specific antibody can bind with a specific antigen only. Thus the term antigen signifies antibody generator.

Read and Learn More Class 9 Life Science

• Antigens are usually proteins and polysaccharides (very rarely lipid). Some common antigens examples are bacteria, viruses, other microorganisms, or their body parts.
• Some foods or others may cause allergic reactions in our bodies called allergens.
• Allergens are also antigens that may cause a vigorous immune response.
• A few examples of allergens are dust, some drugs, food (like egg, prawn, brinjal, milk or milk products, etc.), and so on.

Antibody: An antibody is a protein produced by the body in response to a specific antigen and is capable of combining with the specific antigen only.

• An antibody is a protein known as Immunoglobulin (l_g), a Y-shaped structure, produced by plasma cells (modified B lymphocytes)

Structure of antibody: Each antibody molecule has four peptide chains two small ones called light chains (L) and two longer ones called heavy chains (H). So an antibody may be represented as H₂L₂. All the chains are interconnected by chemical bonds.

Types of antibodies: Antibodies are generally five types l_gG, I_gA, I_gM, I_gD, I_gE (GAMDE)-of which I_gG is most abundant in the body.

Antigen-Antibody interaction :

• Epitope: This is the functional site of an antigen, which binds with the antibody.
• Paratope: This is the functional part of an antibody, which binds with the epitope of an antigen.

During antigen-antibody interaction, the epitope of the antigen binds with the paratope of the antibody.

Leucocytes: You know that leucocytes (WBC) can be of different types. All of them help in the immune system of our body. example

1. Monocytes and neutrophils are responsible for the phagocytosis of germs.
2. Basophil and Eosinophil respond to allergy.
3. Lymphocyte plays the most crucial role in immunity.

Role of Lymphocyte:

1. Large lymphocytes are immature. During maturation large lymphocyte gradually loses cytoplasm and becomes a small lymphocyte that is matured:
2. Small lymphocytes can be of two types B-lymphocyte (Bone marrow-dependent lymphocyte) and T-lymphocyte (thymus-dependent lymphocyte).
3. B-lymphocyte is produced and matured in bone marrow, whereas T-lymphocyte is produced in bone marrow but is matured in the Thymus gland.
4. When the B-lymphocyte is stimulated by an antigen, it produces a specific antibody. This is called humoral immunity.
5. T- lymphocyte recognizes the antigen or part of the antigen. This is known as cellular immunity.
6. T- T-lymphocytes stimulate B-lymphocytes to form antibodies.

Do you know, there are various sub-types of T and B-lymphocytes with specific functions?

Types of immunity:

1. Inherited Immunity (Innate Immunity): This immunity is present at the time of birth example Different types of WBC are present in the blood of a newborn baby. These WBCs will protect the baby against antigens as soon as it is exposed to air outside the mother’s body immediately after birth.
2. Acquired Immunity: The type of immunity that is acquired by a person during his lifetime is called acquired immunity.
3. Active immunity: When a person is exposed to an antigen, the lymphocyte of his own body produces antibodies. This is called active immunity.
4. Passive Immunity: When preformed or readymade antibodies are directly given to a person to protect the body/it is called passive immunity.

Types of immunity Example

• Acquired active natural immunity: Once someone suffers from pox, generally pox virus cannot attack him anymore.
• Acquired active artificial immunity: Vaccination and stimulation of lymphocytes to produce antibodies, for example, Injection of cholera vaccine.
• Acquired passive natural immunity: Mother’s I_gA enters the body of the baby along with milk; the mother’s IgG enters the fetus through the placenta.
• Acquired, passive artificial immunity: Performed antibody (antivenom) from a rabbit or horse may be injected into a snake bite patient.

Concept Of Vaccine

Vaccination (Immunisation):

• The process by which weak or dead pathogens (antigens) are injected into the body to produce immunity against infectious disease by producing antibodies is called vaccination.
• The principle of immunization or vaccination is based on the property of “memory’ of the immune system.

How do vaccines work in our body? Vaccines “teach” our body how to defend itself when germs, such as viruses or bacteria etc, invade the body.

The steps are

1. The body is exposed to very small, very safe amounts of viruses or bacteria that have been weakened or killed.
2. Our immune system then learns to recognize and attack the infection, if our body is exposed to that infection later in life.
3. As a result, our body will not become ill or we may have a milder infection. This is a natural way to deal with infectious diseases.

Probably all of you know that a computer can learn to identify something when proper “software” is loaded on the hard disc. In the vaccination process, the vaccine acts as “software” to develop a “learning process” in the immune system of the body. This vaccine is software, and the immune system is the “hard disc” of the body.

• Uses of vaccination: A vaccinated person develops immunity against diseases like Mumps, Tuberculosis (TB), Rabies (causing hydrophobia), Polio, Cholera, Measles, Tetanus, Typhoid, Smallpox, and so on when vaccines for those diseases are injected into their body.
• Historical perspective: Edward Jenner and Vaccination: For many centuries, smallpox devastated mankind. In modern times, we don’t have to worry about smallpox. We are grateful for the remarkable work of Edward Jenner. With the rapid advancement of vaccination, the historic origin of immunization is often forgotten.
• Edward Jenner (17 May 1749-26 January 1823) was a British physician and scientist who was a pioneer of smallpox vaccine, the world’s first vaccine. He is often called “the father of Immunology”. It is said that “Jenner’s work saved more lives than the work of any other human.”
• Jenner observed that milkmaids were generally immune to smallpox. Cowpox is a disease in cows, similar to smallpox, but much less virulent.
• Jenner noticed that cows suffering from cowpox form blisters from where pus comes out. While handling the cow, milkmaids received this pus from a cow.
• This cowpus protected the milkmaids from smallpox. Jenner collected this pus from cows and also from cowpox blisters on the hands of milkmaids.
• He then inoculated the material to different persons who developed immunity against smallpox and did not suffer from smallpox anymore.
• Jenner’s discovery was accepted and vaccination was recognised in 1840 by the British Government.

Different types of vaccines with examples: Vaccines are made using different processes. They may contain live germs that are attenuated (weakened or altered so as not to cause illness); inactivated toxins; or simply segments of the pathogen. Some common vaccines are mentioned below:

Pathogen And Parasite Causing Human Disease:

Concept And Components Of Wash And Significance In Eliminating Disease Burden

Concept of WASH :

• WASH refers to “Water, Sanitation and Hygiene” which is an international development program that campaigns for access to safe water, adequate sanitation, and proper hygiene education—thus reducing illness and death from disease, reducing poverty, and increasing socio-economic development. WASH is primarily concerned with public health.
• Sanitation: It is the hygienic means of promoting health through the protection of humans against hazards of waste as well as the treatment and proper disposal of sewage waste water.
• Hygiene: It is a set of practices performed for the preservation of health. Some regular hygienic practices may be considered “good habits.”
• UNICEF (United Nations International Children’s Emergency Fund) or WHO (World Health Organisation): Joint Monitoring Program (JMP) (Published in 2013): 36% of the world’s population (2.5 Billion people) lack improved sanitation facilities, and 768 million people still use unsafe drinking water sources. Due to this problem of drinking water and poor hygiene practices, every day thousands of children become sick and ultimately die.

Children particularly girls are denied their right to education because their schools lack private and decent sanitation facilities.

• Women are forced to move a long way to fetch drinking water daily. Without WASH, proper development is impossible.
• Global access to safe water, adequate sanitation, and proper hygiene education can reduce illness and death from disease.
• Thus it may help in the reduction of poverty and on the other hand better socio-economic development.
• So many developing countries are challenged to provide these necessities to their people so they are at risk of WASH-related diseases.

Components of WASH: Water is considered to be the most important component (resource) for sustaining ecosystems. Water provides life-supporting services for people, animals, and plants.

• Because contaminated water is a major cause of illness and death, water quality is a determining factor in human poverty, education, and economic progress.
• Unfortunately, water quality all over the world is declining due to various factors of water pollution such as population growth, rapid urbanization, industrial discharge of chemicals, etc. Thus health of humans as well as the quality of the ecosystem is badly threatened.
• UNICEF and WHO work on different aspects of WASH all over the world. Their work is primarily to eliminate disease burden as far as possible.

The work is divided into six core activities:

1. Drinking water quality management.
2. Water supply and sanitation monitoring.
3. Cholera surveillance and prevention.
4. Water and sanitation in different settings.
5. Water resources management.
6. Other activities.

Importance (Significance) of WASH: The overall objective of UNICEF’s WASH program is to minimize avoidable mortality and morbidity among people.

• Poor sanitation contributes to about 7,00,000 child deaths from diarrhea each year.
• Creating sanitation infrastructure for everyone (citizens of the world) is a major challenge.
• If we improve the technology to deal with human waste we can save lives, and improve child health, and personal safety (particularly for women and girls).
• Improvement of toilet design can help governments and NGOs to meet the enormous challenge of public sanitation services.
• All UNICEF programs are designed to improve WASH all over the world.

Microbes In Human Welfare In Our Everyday Life Microbes In Biocontrol Agents

The natural method of pest and pathogen control in which viruses, bacteria protozoa, etc. are used is called biocontrol or biological control.

• The chemicals that are used in agricultural fields as pesticides and insecticides are very poisonous and harmful to human beings including animals.
• Bacillus thuringiensis, a bacterial species has the power to kill different insects for example moths, beetles, ants, termites, etc.
• The bacterium possesses some insect-killing crystal proteins, of which one of them is known as trioxide.

Microbes In Biocontrol Agents Examples: In connection with biological control some examples are cited below :

• Insects: Ladybird beetles provided with red and black markings live by eating aphids. Dragonflies prey upon mosquitoes for their food.
• The insect Neochetina introduced from Latin America to India is used to control aquatic floating plant water hyacinth (Eichhorina crassipes). On the swollen petiole of the water hyacinth, the female insect lays an egg.
• From the eggs, larvae develop which take the petiole as food, and in turn, the adults feed on leaves, finally the destruction of the entire plant results.
• Fungus: Biological control is influenced by the free-living fungus Trichoderma over some plant pathogens.
• Bacteria: Bacillus thuringiensis (Bt) can be utilized to control butterfly caterpillars which acts as a microbial biocontrol agent.

For reference only: The above-mentioned bacteria are available in sachets as dried spores in the market, which are mixed up with water and sprayed by a sprayer in those plants that are exposed to being attacked or harmed, such as Brassica and fruit trees, where these are taken as food by the larvae of the insect.

• Finally, the larvae get killed when the toxin is released in the gut of the larvae.’The toxins formed kill only the caterpillars but do not cause any harm to the other insects.
• Bacillus thuringiensis toxin genes (crygene) when introduced into cotton plants by scientists, plants got the power to resist the attack of insect pests example Bt. cotton, which is cultivated in some States. India.
• Bacillus thuringiensis (Bt) is one of the most important examples of soil bacterium. The spores of this bacterium possess the insecticidal insect-killing substance called cry protein. For that reason, the spores produced by the bacterium have the power to kill certain larvae of the insects.

Virus: Another pathogens are Baculoviruses which attack insect pests and some other arthropods.

• The genus Nucleopolyhedrovirus is one of the baculoviruses caused by biocontrol agents.
• These viruses are very good entities for species-specific.
• They do not show any negative impacts on plants, mammals, birds, fishes, etc.

Microbes As Biofertilizers

Microbes As Biofertilizers Introduction: Biofertilizers reduce the dependence on chemical fertilizers and do not pose pollution problems. Crop rotation techniques improve soil fertility.

• Cereal crops (wheat, rice) when alternated with legume crops (peas, beans) improve the fertility of the soil. The introduction of biofertilizers to agriculture helps in combating, the adverse effects of synthetic agricultural chemicals. Materials of biological origin are used to improve soil fertility.
• The role of bacteria, cyanobacteria, and mycorrhiza as biofertilizers: Micro-organisms like bacteria, cyanobacteria, and fungi when added to the soil, enrich the soil nutrients due to their biological activity and thereby increasing the nitrogen content of the soil by nitrogen fixation, called biofertilizers.
• Significance of Biofertilizers: To increase the output in cases of high-yielding varieties of crop plants chemical fertilizers are being used in heavy amounts. Besides accumulating in the crop plants, chemical fertilizers cause pollution of organisms living in aquatic conditions, further in groundwater.
  • For that reason, environmentalists are pressurizing farmers to go for organic farming leaving the chemical fertilizers.
  • Manures, biofertilizers, and biocontrol agents provide necessary nutrients to crop plants so that the pests and pathogens may remain under necessary control without causing any harm to the crops.
  • Bacteria, Fungi, and Cyanobacteria are the major sources of biofertilizers.
  • Some of the most important and functional biofertilizers generally recommended for use in agricultural land are stated below :

Role of Bacteria :

Release of phosphorus: Some bacteria like Bacillus polymax, Pseudomonas striata, and species of fungus Aspergillus have the power to release phosphate from bound or immobile These biofertilizers are called microphos.

• The above two bacteria are phosphate-dissolving bacteria due to the secretion of some organic acids like lactic, formic, acetic, fumaric, etc. They have the power to reduce the pH of the substrate.
• This process helps them to release the soluble Inorganic phosphate Into the soil (H₃PO₄) due to the decomposition of phosphate-rich organic compounds.

Fixation of N₂: Free-living soil bacteria Azotobactcr and Bacillus polymyxa fix atmospheric nitrogen and provide it to crops like cereals, millets, fruits, and vegetables resulting in their increased yield. Clostridium, Bcijernickia, Dcrxio, Klebsiella, and Rhodos-like bacteria can also fix atmospheric nitrogen.

• With the help of these bacteria, the fertility of soil takes place whereby the yield of crops increases. This also saves the application of nitrogen fertilizers in the soil.
• The bacterium Azotobactcr existing in the fields of rice, maize, cotton, and jowar not only helps to increase the yield of those crops but also saves the supply of nitrogen fertilizer in those fields, its inoculation can be obtained from the market under the trade name a zoo bacterin, whose application in the field can give good result.

Symbiotic nitrogen-fixing bacteria: Hellriegel and Wilfarth (1888) showed that the leguminous plants with root nodules were able to increase the percentage of nitrogen in the soil.

• Within the root nodules reside a type of bacterium.
• They suggested that there lies a symbiotic relationship between the nodule bacteria and the host plant. That symbiotic bacterium was named Bacillus radicicola by Beijerinick (1888).
• Later on, it was renamed as Rhizobium leguminosarium by Frank (1890).

For reference only:

The gram-negative, rod-shaped bacterium Rhizobium enters from the soil as infection thread into the roots of Leguminous plants, where due to the influence of certain substances like biotin or amino acid, enzymes, sugars, and vitamins, may cause the root cells to divide forming root nodules.

• Certain growth substances like Indole Acetic Acid (IAA) secreted by the bacteria cause root hairs to curl.
• Symbiotic nitrogen-fixing bacteria Rhizobium leguminosarium resides in the root nodules of leguminous plants and converts nitrogen of air to soluble nitrates.
• Nitrates are used by host plants which results in increased growth and yield.
• With the death of host plants, root nodules release bacteria as well as nitrates into the soil whereby increases the fertility of the soil.
• Symbiotic bacteria Rhizobium fixes atmospheric nitrogen in the presence of a pigment called leghaemoglobin in anaerobic conditions only.

For reference only: Within the root nodules of leguminous plants lies a hemoglobin-like compound called leghaemoglobin (LHb) the only hemoglobin-like protein found to be present in higher plants.

• It facilitates the diffusion of oxygen (O₂) to the very rapidly respiring nitrogen-fixing symbiotic bacteroids within the root nodule cells, thereby stimulating ATP production.
• The addition of phosphate fertilizer increases the efficiency of nitrogen fixation and in turn, increases crop yield.
• Frankia, a nitrogen-fixing mycelial bacterium of Actinomycetes is associated symbiotically with the root nodules of several non-leguminous plants like Casuarina, Myrica, Rubus, Alnus, etc.

Id Role Of Cyanobacteria: Many free-living Cyanobacteria (blue-green algae) have the power to fix nitrogen in the atmosphere example Anabaena, Nostoc, Aulosira, Tolypothrix, Cylindrospermum, etc.

• In aquatic and also in terrestrial conditions they act as bio-fertilizers. According to Aiyer (1972), Aulosira fertilissima is regarded to be the most effective nitrogen-fixing bacterium in the rice fields of India.
• Cylindrospermum form grows in the fields of maize and sugarcane and acts also as a good nitrogen fixer.
• The application of cyanobacteria in agricultural fields is popular due to its low costs and good efficiency.

Azolla-Anabaena symbiosis: Anabaena azollae, a cyanobacterium lives in cavities of leaves of a fast-growing aquatic fern Azolla, helps in nitrogen fixation, and in return excretes nitrogenous compounds into the leaf cavity of the fern. Application of Azolla in the rice fields results in an increased yield.

For reference only: Loosely associated nitrogen-fixing soil bacteria Azospirillum lipoferum increases the yield of plants.

Importance Of Biofertilizers

1. The yield of plants can be increased by 15%-35% by the application of biofertilizers.
2. The inoculum which has to be applied in the field can be prepared by the farmers themselves.
3. The soil texture was improved by the biofertilizers.
4. In semi-arid conditions biofertilizers are also effective, giving a good result.
5. They disallow pathogens to grow vigorously.
6. Some vitamins and growth-promoting biochemicals can also be produced by them.

Role of Mycorrhiza: The symbiotic association of some fungi with the roots of seed-bearing plants is called mycorrhiza.

Types of Mycorrhiza: Two types

1. Ectotrophic mycorrhiza or Ectomycorrhiza: in this case, the fungus lives outside the tissues of roots of Pine, Oak, Eucalyptus, Alnus, Betula, etc. The fungus replacing the normal root hairs of the plants forms a covering or mantle outside the roots of trees.

• This mantle serves as root hair and increases the surface area of absorption, thereby increasing the uptake of water and mineral nutrients and in turn increasing plant vigor, growth, and yield.
• This mycorrhiza absorbs’ and stores nitrogen, phosphorus, potassium, and calcium in its fungal mantle.

For reference only: Simpler organic molecules are formed from complex organic molecules by them.

• They’d also convert insoluble organic compounds into soluble and easily absorbable forms.
• A network is formed when the fungal hyphae penetrate the intercellular spaces of the cortex of the root to finally form a net-like structure. This is called Hartig net.

2. Endotrophic mycorrhiza or Endomycorrhiza: When a fungus lives inside the root cortex and does not form a mantle on the surface of the root, this mycorrhizal association is called endotrophic mycorrhizal.

• These associations are found in herbaceous species like orchids and some woody plants.
• Here fungus produces loosely interwoven hyphae, some of which penetrate the soil while others grow on the root cortex. In the cortex, some hyphae grow in between the cortical cells, while some penetrate the cortical cells forming swollen vesicles or finely branched hyphal masses called arbuscles.
• This fungal association is called vesicular-arbuscular mycorrhiza (VAM). Mycorrhizal association is noted in the root of legumes, cereals, tobacco, soybean, and many orchids like Vanilla, Neottia, etc.

Importance of Mycorrhizas About Plants:

1. They (endotrophic mycorrhiza) increase the life span of the roots of plants by providing food to them.
2. They (ectotrophic mycorrhiza) increase the surface area of the roots of host plants by mantle formation.
3. Fungus spread their mycelia into the soil where they absorb different kinds of nutrients causing increased growth of the plant.
4. Mycorrhizas play an important role by absorbing selective elements like Ca, K, Fe, Br, Cl, S, and N which move easily. It also absorbs elements like Zn, Cl, and P that do not move easily.
5. Some of the mycorrhizas produce metabolites that can change the power of plants to develop roots from plant cuttings. They enhance the development of roots during vegetative
6. The resistance power of plants also increases. They make less effect of pathogens and pests on host plant health so that they become free from illness.

Know the facts

1. The symbiotic association of fungi with plants is called mycorrhiza.
2. Micro-organisms like bacteria, cyanobacteria, and fungi when added to the soil, enrich the soil nutrients due to their biological activity and thereby increase the nitrogen content of the soil by nitrogen fixation are called biofertilizers.
3. Two nitrogen-fixing blue-green algae are Nostoc and Anabaena.
4. One symbiotic nitrogen-fixing bacterium is Rhizobium leguminasarium which lives in the root nodules of pea plants.

Physiological Processes Of Life

Photosynthesis

Photosynthesis Introduction: All living organisms need energy to perform their different normal metabolic functions. Food is the source of potential energy or stored energy.

• During oxidation it is converted to kinetic energy, this is called Respiration. From this kinetic energy, the necessary energy is supplied to the living body.
• The green organisms using a special physiological function produce food.
• During this physiological function, the solar energy is stored within the food as potential energy and this special physiological function (process) is called Photosynthesis.

Concept of Photosynthesis

The term ‘photosynthesis’ (Photos, light: synthesis, building up) was coined by Barnes in the year 1898.

• The green cells synthesize enormous amounts of food materials with the help of light energy, preferably available from the sun.
• Carbohydrate (starch) which is produced as a result of photosynthesis acts as the basic raw material because this carbohydrate is directly or indirectly converted to all types of organic compounds, which are needed for the entire living world.

Concept Of Photosynthesis Definition: Photosynthesis is the photochemical, biochemical, anabolic, and oxidoreductive process by which green plant cells can prepare carbohydrate food material in the presence of sunlight, M₂0, CO_2, and chlorophyll, producing O₂ as a by-product.

Read and Learn More Class 9 Life Science

Explanation And Overall Reactions :

1. During photosynthesis 6 molecules of carbon dioxide react with 12 molecules of water forming 1 molecule of glucose, 6 molecules of water, and 6 molecules of oxygen.
2. The reaction occurs in the presence of sunlight and chlorophyll.
3. The number of molecules of O₂ evolved during this process equals the number of molecules of CO₂ taking part in the process.
4. The end products formed as a result of photosynthesis are water, oxygen, and glucose.

Characteristics Of Photosynthesis:

1. It is a photochemical process because this chemical reaction occurs only in the presence of photon particles of sunlight.
2. It is a biochemical process because this chemical process occurs only in the living plant cell.
3. It is an anabolic process because, during this constructive process, glucose is synthesized causing an increase in the dry weight of the cell.
4. It is an oxidoreductive process because during this process H₂O is oxidized by losing Hf whereas CO₂ is reduced by gaining H+.
5. By this process, green plant cells can prepare carbohydrate food material in the presence of sunlight, H₂O, CO_2, and chlorophyll.
6. During this process, CO₂ is absorbed and O₂ is evolved which is just the reverse of aerobic respiration.
7. This is an endergonic process since solar energy is absorbed in this process.
8. This process plays a very significant role in maintaining the O₂-CO₂ balance.

Chemical Transformation Or Transfer During Photosynthesis :

1. C and O of CO₂ enter into c₆H₁₂O₆
2. H of H₂O enters into C₆H₁₂O₆
3. O₆of H₂0 evolves as free O₂.

Important Facts On Photosynthesis

1. Photosynthesis an anabolic process: Photosynthesis is an anabolic process due to the following reasons—
2. Photosynthesis is a constructive process, resulting in the formation of new cellular
   materials.
3. It increases the dry weight of the organism.
4. Energy is stored in the form of potential energy in glucose molecules. 1 mol of glucose contains 686 kcal of energy.
5. Complex substance (glucose) is produced from simpler substances water, carbon dioxide, etc.
6. By this process, micromolecules combine to form macromolecules. For example, water (H₂O) and carbon dioxide (CO₂) are micromolecules, which combine to form glucose (C₆H₁₂O₆), which is a macromolecule. The sources of carbon and oxygen for glucose is CO₂

Know The Facts:

1. Main Organ of Photosynthesis Leaf,
2. Organelle of Photosynthesis The Chloroplastid.
3. Photosynthetic pigment Chlorophyll.

Photosynthetic unit-the Quantasomes: Presently quantosome is known as antenna 1 complex. The ‘photosynthetic units’ or ‘quanta somes’ represent an aggregation of several chlorophyll molecules.

• These are the main photosynthetic pigments along with accessory pigments, like carotenoid (carotene, xanthophyll) and proteins or phycobilins [phycocyanin (blue), phycoerythrin (red)].
• They are capable of capturing and converting solar energy into chemical energy in the form of ATP, during the light phase.
• Photosynthesis may also take place in the presence of artificial light (if the light intensity is sufficient) at a very slow rate.

Site Of Photosynthesis:

Main site of photosynthesis: Photosynthesis takes place within the chloroplast containing mesophyll tissue palisade parenchyma cells and spongy parenchyma cells, present between the upper and lower epidermis of the dorsiventral leaf.

• However, all chlorophyll-containing plant parts have the power of photosynthesis.
• Chloroplast containing chlorophyll is present in abundance in the mesophyll tissue r of the leaf.
• So the cells of the mesophyll tissue are the main site of photosynthesis
• To some extent, photosynthesis occurs in the green part of a growing stem Example, Opunti  (B. Phanimanasha), and Logenaria (B. Lau).
• Photosynthesis also takes place in the thalamus of the flower which is a modified stem, in the roots, and the sepals of the green calyx of the flower.

Velamen: Epiphytic root of orchid, can perform photosynthesis. They are hanging roots and are green in color. These epiphytic roots do not reach to soil.

• So they have the problem of absorbing water.
• At the tip of the epiphytic root, there is a soft spongy structure called f velamen that can absorb atmospheric moisture.
• This moisture serves the purpose of water.

Things To Remember

Non-Photosynthetic plants:

1. Plants without chlorophyll cannot photosynthesize. Examples Some bacteria and fungi.
2. Roots cannot photosynthesize, due to a lack of photosynthetic pigment chlorophyll and

• Non-availability of sunlight, as it grows under the surface of the soil.
• Exceptions-Aerial roots of Orchid (Epiphytic roots of Vanda Rasna) and assimilatory roots of Tinospora-B.
•  B-Gulancha can perform photosynthesis due to the presence of chlorophyll.

Brief Outline Of The Roles Of Different Components Of Photosynthesis

CO₂ H₂oSunlight And Pigment Chlorophyll And Carotenoids:

Carbon dioxide: The carbon element of the gaseous compound CO₂ is directly taken 3y green plants from the atmosphere.

Role: In terrestrial plants, CO₂ enters the mesophyll tissue cells by diffusion through the stomata or lenticel.

In submerged aquatic plants, CO₂ enters the plant body by diffusion through the body surface of the plants. ‘

1. During dark reactions within the stroma of the chloroplastids, carbon of CO₂ is accepted by a five-carbon compound RuBP (Ribulose 1-5 bisphosphate).
2. The CO₂ is reduced to glucose through successive steps of enzymatic reaction.
3. The carbon and oxygen of CO₂ form the carbon and oxygen of glucose (C_gHO_g).

Water: Water is one of the chief components of photosynthesis.

Role: In terrestrial plants, absorption of water from soil takes place through the unicellular root hairs, by the process of diffusion and osmosis.

1. Water diffuses into the mesophyll cells and from there into the chloroplasts. About 1% of the total amount of water absorbed by plants is required for photosynthesis.
2. Water molecule breaks up into H+ (hydrogen ion) and OH” (hydroxyl ion) by light-activated
   chlorophyll molecule.
3. Oxygen formed from hydroxyl ions is liberated through stomata.
4. The hydrogen ion is accepted by NADP+ and it gets converted to NADPH₂. Water is produced from the hydroxyl ion.
5. Hydrogen in water reduces CO₂ to glucose.

H₂O→H+OH,OH-e(Electron)=OH radical

4OH=2H₂O+₂

The hydrogen of water forms hydrogen.of glucose. H₂O is the source of liberated oxygen during photosynthesis.

Sunlight: Solar radiation composed of highly energized invisible solar particles called quanta or photons is required for photosynthesis.

Role:

1. 0-1% to 2% of total light solar radiation is absorbed by chlorophyll molecules.
2. The highly energized photon particles of light activate the chlorophyll molecules liberating electron which then causes photolysis of water,
3. Light causes photophosphorylation

ATP acts as the chief source of energy currency: The rate of photosynthesis is influenced by the intensity, quality, and duration of light.

• Strong light may even stop the photosynthetic process, or slow down its rate, a phenomenon called solarization.
• About 2400 kcal light energy is required for the synthesis of 1 mole of glucose.

Pigments: Chlorophyll and Carotenoid’s main photosynthetic pigment is chlorophyll, which is present in the thylakoid of grana in the chloroplast.

Role :

1. When a photon particle strikes the chlorophyll molecule, an electron goes out of chlorophyll. Soothe chlorophyll becomes positively charged.
2. This positively charged. chlorophyll is known as activated chlorophyll where different events of light reaction can start.
3. In the activated chlorophyll in the presence of sunlight, H₂O breaks down into H and OH known as photolysis.
4. In the activated chlorophyll, ATP is produced by photophosphorylation.

Plant pigments: Plants may contain two types of pigments, green-colored chlorophyll, and yellowish-orange-colored carotenoid.

Chlorophylls are of two types

1. Chlorophyll a (C₅₅H₇₂O₅N₄Mg) and
2. Chlorophyll b (C₅₅H₇₀O₆N₄ Mg), Chlorophyll c, d, and e are also present.

For reference only :

Chlorophyll atoms are arranged in a circle with the help of four pyrrole rings with Mg atoms at the center. Along with the pyrrole ring is attached phytol (a type of alcohol).

Carotenoids are of two types 

• Carotene (C₄OH₅₆)Orange orange-colored and Xathophyll (C₄₀H₅₆O₂) is the yellow-colored pigment.
• Phycocyanin blue colored and Phycoerythrin the lavender red-colored pigments.

Carotenoids: Carotenoids are yellow, brown, or orange pigments found in close association with chlorophylls in all photosynthesizing cells.

• They occur in thylakoids and act as accessory pigments of photosynthesis.
• They are present in nearly all higher plants, algae, and some microorganisms.

For reference only: Goodwin (1960) suggested that the chlorophylls and carotenoids may be attached to ‘ the same protein, forming a complex known as photosynthesis.

Carotenoids Are Of Two Types:

1. Carotenes: They are orange to yellow and are unsaturated hydrocarbons (C₄OH₅₆). They are insoluble in water but readily soluble in chloroform, ether, and carbon disulfide. They absorb blue and green lights and transmit yellow and red light. Four isometric forms of carotenes are now recognized a, 3, y, and 8 of which (3-carotene is most common in all green plants).
2. Xanthophylls or Carotenols: They are yellow with empirical formula C₄OH₅₆O₂.ln normal green leaves, proportionately there is more xanthophyll than carotene. The most common
   xanthophyll in green leaves insulator or lutein. (Tomato is dark red due to lycopene pigment).

Apart from their role in the absorption of light energy and its transfer to chlorophyll, carotenoids play a very important role in protecting chlorophyll molecules from photooxidation in scorching sunlight.

What Will Happen

1. When a portion of the grassland chosen is. covered with an earthenware pot. Small stones are placed between the edge of the pot and the ground. What is observed when the pot is removed after a few days?
2. Two healthy potted plants are selected and kept in an airy place under light. An adequate amount of water is given to the seedling of one pot and water is not provided to the seedling of the other pot. What will be observed in the potted seedlings after seven days?

 Explanation of absorption and action spectra

Absorption Spectrum :

Absorption Spectrum Definition: The absorption spectrum is the pattern of absorption of light at different wavelengths by the object.

• Colored pigments absorb only visible light.
• Spectrophotometric analysis shows that chlorophyll and chlorophyll can absorb maximum blue color (429 mp 453 mp. wavelength) and second maximum red color (642 mp 660 mp, wavelength).
• That’s why maximum photosynthesis occurs in the blue and red colors of the visible spectrum.
• The carotenoid pigments play a role in photosynthesis by absorbing light and passing it to chlorophyll where it is used in the photosynthetic process.
• Absorption spectra are one of the properties of chlorophyll, during which they can absorb a certain wavelength of light.

Do you know that minimum action and absorption occur in green light? That why minimum photosynthesis occurs in the green color of the visible spectrum.

Photosynthetic Process Light-Dependent Phases And Dark Or Light-Independent Phase

Photosynthesis is a complex photochemical reaction involving a series of reactions occurring in light as well as in darkness, leading to the formation of glucose.

• The light phase triggered by light energy was discovered by Robert Hill (1940), hence it is termed the Hill reaction.
• The dark phase, independent of light, was discovered by F. F. Blackman (1905) and is called Blackman’s reaction or chemical reaction.
• The light phase occurs granum (pi. grana) of the chloroplast and the dark phase occurs within the stroma of the chloroplast.

1. Light phase: The reductive reactions taking place in the presence of light within the grana are called the light phase.
2. Light phase Definition: During photosynthesis, various oxidoreductive reactions that occur in the grana of chloroplast in the presence of solar energy (photon) are together called a light reaction or light phase.
3. Occurrence: The light phase occurs in the grana of chloroplast.
4. Requirements: For light reactions, essential requirements are photon particles of sunlight, chlorophyll, and H₂O.
5. Products: After different steps of light reaction, the end products are ATP, NADPH (reduced NADpj, H₂O, and O_2.

Different steps of light reaction: Activation of chlorophyll, Photolysis, Evolution of O₂, Formation of NADPH (Reduced NADP), and Photophosphorylation. These steps can be explained as follows:

Activation of chlorophyll: When a photon particle strikes the chlorophyll molecule, an electron goes out of chlorophyll so the chlorophyll becomes +vely charged. This +vely charged chlorophyll is called activated or excited chlorophyll and this phenomenon is called activation or excitation of chlorophyll.

In this activated chlorophyll, other events of light reaction start.

Photolysis: In the activated chlorophyll in the presence of sunlight, H₂O. breaks down into H⁺ and OH^–. This is called photolysis.

Evolution of O₂: OH- produced by photolysis donates electrons to chlorophyll and becomes OH. Several OHs combine to form H₂O and O₂. This O₂ goes out of plant leaf. Hence the O₂ evolved during photosynthesis comes from H₂O and not from CO₂.

Formation of NADPH (Reduced NADP): NADP is known as a Hill reagent. NADP+ receives electrons from OH” and H+ from H₂0 and thus forms NADPH (reduced NADP).

NADPH produced in the light reaction is utilized in the dark reaction.

Photophosphorylation: In the activated chlorophyll in the presence of sunlight, ADP and Pi combine to form ATP. This is called photophosphorylation.

For reference only: When a photon particle strikes the chlorophyll molecule, an electron goes out of chlorophyll.

• This electron while passing through different electron carriers generates energy (redox potential).
• This energy helps in the combination of ADP and Pi to form ATP.

For reference only: Photophosphorylation can be of two types Cyclic photophosphorylation and non-cyclic photophosphorylation.

Different Steps Of Light Reaction :

Summary Of Light Reaction :

Sequence of Light-dependent phase :

Entrapping of sunlight→ activation of chlorophylls photolysis of waters formation of the end product of light-dependent phase NADPH + H⁺,O₂ and ATP, H₂O also formed.

Know The Fact

A new concept for the photolysis of water : As oxygen does not exist in atomic form oxygen produced by splitting one molecule of water is written a O₂. Two water molecules produce one molecule of oxygen which is later released into the atmosphere.

The breaking of water by light takes place indirectly by oxidizing P680 molecules.

Outline steps of dark reaction :

The dark reaction occurs in the stroma of the chloroplast. It is purely an enzymatic process. The most important enzyme is known as RuBisCO (Ribulose Bisphosphate Carboxylase Oxygenase).

• here. are many steps of dark reaction. Initial steps were discovered by Blackman but details of dark reactions were discovered by Calvin, Benson, and Bassham for which they were awarded the Nobel Prize.
• Hence the detailed steps of dark reaction are also called Calvin’s cycle.
• Dark reaction is fully dependent on light reaction. In the daytime in the presence of sunlight, a light reaction occurs in the grana of the chloroplast.
• The main products of the light phase ATP and NADPH are immediately utilized in dark reaction (Since ATP and NADPH cannot be stored in plant cel1).
• At night, in the absence of sunlight, the light reaction stops—so production of ATP and NADPH will be also stopped and hence dark reaction cannot continue.
• That’s why, a dark reaction does not occur in darkness.

Different Steps Of Dark Reaction Are As Follows :

1. 6 mol RuMP (Ribulose Mono Phosphate), a 5-C compound, is concerted into 6 mol RuBP (Ribulose Bisphosphate) (Total no. of carbon 6×5 = 30) in the presence of 6 ATP.
2. 6 mol RuBP bind with 6CO₂ to form 6 mol Diphosphoribitol, (a. 6-C compound, which is very unstable) (Total no. of carbon 6×6 = 36).
3. 6 mol Diphosphoribitol quickly breaks into 12 mol PGA (Phosphoglyceric acid), a 3-C compound (Total no. of carbon 12 x 3 = 36). PGA is the first stable product in photosynthesis.
4. 12 mol PGA is converted into 12 mol DPGA (Diphosphoglyceric acid) (No. of carbon 12 x 3 = 36) with the utilization of 12 mol ATP.
5. 12 mol DPGA is transformed into 12 mol PGAId (Phosphoglyceraldehyde) (No. of carbon 12 x 3 = 36) with the utilization of 12 mol NADPH.
6. 12 mol PGAId are divided into two groups. In one group 2 mol PGAId (2×3 = 6 carbon) produces glucose and other carbohydrates through different enzymatic steps.
7. In the other group, 10 mol of PGAId (10 x 3 = 30 carbon) undergoes different enzymatic steps to resynthesize 6 mol RuMP (6 x 5 = 30 carbon). Then the whole cycle is completed with a net production of 1 mol hexose (glucose or fructose).

For completion of one total round of Calvin’s cycle and to produce 1 mol glucose, 18 ATP and 12 NADPH are required. So, ATP and NADPH, produced in light reactions are utilized in dark reactions

For Reference only: Have You heard about C₃ and C₄ plants?

Carbon Assimilation: During the dark reaction of photosynthesis carbon of CO₂ is absorbed and assimilated into glucose. So the process of dark reaction may be called carbon assimilation.

For Reference only: CO₂ is absorbed by RuBP to form PGA. This reaction is catalyzed by the enzyme RuBisCO.

Summary of pathway of Dark Reaction (C₃—Pathway):

Sequence of Light-independent phase (Dark phase):

Relation Between Light Reaction And Dark Reaction :

• ATP and NADPH₂ produced in light reactions are utilized in dark reactions immediately.
• They are not stored. At night in the absence of sunlight, the light reaction stops so the production of ATP NADPH₂ will be also stopped – hence dark reaction can not continue.
• Sp dark reaction is fully dependent on light reaction. That’s why a dark reaction does not occur in darkness.

Difference Between Light Phase And Dark Phase

However, both the light phase and the dark phase occur in the time only. The dark phase does not occur in darkness or at night.

Significance of Photosynthesis

Entrapping of solar energy and conversion of solar energy into potential energy in

The radiant energy of the sun travels as electromagnetic radiation. This radiation is composed of small packets of highly energized invisible solar particles called ‘quanta’ or ‘photons’.

• When a photon particle strikes the chlorophyll molecule, different steps of light reaction start producing ATP.
• In ATP, solar energy is stored as chemical energy. When this ATP is utilized in a dark reaction producing c6H12°6′  solar energy is indirectly transferred into glucose and stored as potential chemical energy.
• This glucose is modified into different forms of food that are the sources of energy.
• In this way, solar energy is indirectly converted into potential chemical energy in different food materials. During respiration, food materials are oxidized when potential energy is released in the form of heat energy.

Solar energy →Chemical energy (in ATP)→ Potential energy (in Glucose) →Kinetic energy (in respiration) Food (storing energy), produced in plants by photosynthesis, is transferred to animals through the food chain and food web.

Storage of Photosynthetic products : In different plants, photosynthetic products are stored in various parts of the plant body.

This Can Be Illustrated As Follows:

Again, in different plants, the photosynthetic end product (mainly glucose) is transformed into various substances by enzymatic reactions and stored in many parts of the plant body.

This Can Be Illustrated As Follows :

O₂ – CO₂Balance In The Atmosphere :

The normal percentage of O₂ and CO₂ in the air is 21% and 0-03% respectively. Oxygen used during respiration and combustion causes oxygen deficit in the atmosphere which is balanced by the O₂ liberated during photosynthesis by green plants. CO₂is liberated during respiration, and

combustion which is absorbed during photosynthesis by green plants. Thus O₂ — CO₂ balance is maintained. The average percentage of dissolved O₂ in water is nearly 0-7%.

For reference only:

• Compensation point: The compensation point is the light intensity where the rate of photosynthesis exactly matches the rate of respiration.
  • At this point, the amount of C02 evolved in respiration in mitochondria is utilized by the chloroplast for photosynthesis and the amount of O₂ evolved by photosynthesis in the chloroplast is utilized in mitochondria for respiration.
  • So, there is no net exchange of O₂ and CO₂ between the leaf and the atmosphere.
• Time factor: The rate of photosynthesis is directly dependent on the intensity of sunlight. At different times of the day intensity of light varies so the rate of photosynthesis also varies. For example, at dawn or dusk, the intensity of light is low, so the rate of photosynthesis is also slow.
  • But as the day progresses, the intensity of light increases, rate of photosynthesis also rises.
  • This variable rate of photosynthesis at different times of the day is called as time factor.

Mineral Nutrition

Mineral Nutrition Introduction: All living organisms require food. It is needed for growth, movement, reproduction, etc. A living organism either synthesizes or collects its necessary food from the environment.

• The food may be utilized directly or indirectly. The process involved in the conversion of complex food into simpler products or products is termed digestion.
• The digested product (or products) is absorbed within the body and is transformed into constituent(s) of protoplasm by the process of assimilation.
• In addition to energy-yielding food like carbohydrates, proteins ‘ and fats, minerals, vitamins, and water are also required for various life processes.
• All these essential substances are collectively called nutrients. The process that involves ingestion and ‘ digestion of food materials and after that absorption and finally assimilation of absorbed food is called nutrition.

What Are Nutrients?

Nutrient Definition: The organic and inorganic materials that the living organism collects from nature to perform all the fundamental activities of the body are called nutrients.

• All nutrients that are collected by living organisms from their surroundings are not considered food.
• Nutrients do not require digestion. The essential substances like minerals, Vitamins, and water are collectively called nutrients.

What is nutrition?

Nutrition Definition: “Nutrition is the combination of processes by which the living organism receives and utilizes the materials necessary for the maintenance of its functions and for the growth and the renewal of its components – [Turner D. F. (1959)].

Significance or Importance of Nutrition:

1. Promote growth, repair wear and tear of the damaged tissues, and gain energy to control the different metabolic processes are the main functions of nutrition.
2. The potential energy stored within food is transformed into usable energy through nutrition. The different physiological functions of the living body like movement, locomotion, excretion, reproduction, etc. are controlled by utilizing this energy.
3. Through nutrition, the disease-resistant power (immunity) of the living body is developed.
4. Through nutrition, future food matters are stored within the living body. From those stored food (in the plant body mainly as starch and in animals as glycogen and fat) the future energy is produced during food shortage.
5. Nutrition plays a special role in the production of heat energy in the animal body to meet the caloric demands of an individual.

Concepts of Macro and Micro-nutrients with examples:

Macro-element Definition: The inorganic ions (essential elements) that are required in relatively large amounts for normal growth and other physiological functions of plants are called macro-elements.

Examples of macro-elements: Macro-elements are, Carbon (C), Hydrogen (H), Oxygen (0), Phosphorus (P), Sulphur (S), Potassium (K), Nitrogen (N), Calcium (Ca), Iron (Fe), and Magnesium (Mg) respectively. In the absence of any of these elements, the normal growth of the plant is disturbed, and different deficiency symptoms are exhibited by the plants.

Difference between Macro-elements and Micro-elements:

Micro-element:

Micro-element Definition: The essential elements that are required in trace amounts are called trace elements or micro-elements.

Examples are Manganese (Mn), Boron (B), Zinc (Zn), Copper (Cu), Molybdenum (Mo) sometimes Sodium (Na), Iodine (I), Silicon (Si) and Aluminium (Al), etc.

Listing Of Macro-Elements In Plants

Potassium (K): In plants

1. Activates the enzymes and also takes part in carbohydrate and protein synthesis,
2. It helps in the permeability of the cell membrane.

Phosphorus (P): In plants

1. This is necessary to manufacture nucleic acids, phospholipids, coenzymes like NAD or DPN (Nicotinamide Adenine Dinucleotide) or (Diphosphopyridine Nucleotide), NADP or TPN (Nicotinamide Adenine Dinucleotide Phosphate) or (Triphosphopyridine Nucleotide), FAD (Flavin Adenine Dinucleotide).
2. Photosynthesis, respiration, protein, and lipid synthesis, Phosphorus helps in the synthesis of chlorophyll pigment.

Calcium (Ca): In plants

1. It plays an important role in cell wall formation and cell division,
2. Calcium acts as an activator (cofactor) of many enzymes. It occurs in the middle lamella of the cell wall.

Magnesium (Mg): In plants

1. It acts as an activator of enzymes involved in protein synthesis, nucleic acid synthesis,
2. Magnesium is one of the constituents of chlorophylls. Due to a deficiency of Mg, chlorosis occurs in plants.

Sulphur (S) r In plants

1. A component of protein
2. Components of vitamins like thiamine, biotin
3. Helps in the formation of coenzyme A.

Nitrogen (N2): In plants

1. Components of amino acids and proteins,
2. Helps in the formation of ATP and coenzymes,
3. A component of chlorophylls.

Iron (Fe) : (nowadays considered as a microelement) In plants

Takes part in chlorophyll synthesis and respiration, iron is needed in the case of respiratory enzymes and Cytochromes.

Listing Of Micro-Elements In Plants

Manganese (Mn): In plants

1. Helps in enzyme activation;
2. Acts as a catalyst and
3. Acts as an electron carrier.

Copper (Cu): In plants

1. Helps in the reduction of nitrate,
2. Acts as an electron carrier,
3. Component of certain enzymes.

Chlorine (Cl): In plants

1. It influences plant development,
2. Regulates osmotic pressure.

Cobalt (Co): In plants

1. Acts as a growth promoter and is present in Vitamin B12.
2. It activates the plant enzymes like peptidases,
3. In blue-green algae, it is related to nitrogen fixation.

Molybdenum (Mo): In plants: Takes part in nitrogen fixation, nitrate reduction, etc. Acts as an activator of enzymes.

Zinc (Zn): In plants: It is involved in IAA synthesis acts as an activator of many enzymes and helps in protein synthesis.

Boron (B): In plants

1. The growth and development of plants are influenced when it is present in minute amounts,
2. Helps in carbohydrate translocation and
3. Prevents phenolic acid storage toxicity.

Iodine (I): In plants: Helps in plant metabolism, without it the growth of the plant is disturbed.

Sodium (Na): In plants:

1. Essential only for certain species of green algae,
2. Helps in the vigorous development of varieties of plants by its presence in the soil.

Fluorine (F): In plants: Not known.

General Functions Of Essential Mineral Nutrients

The general functions of essential mineral nutrients are

1. Formation of protoplasm: The formation of a major part of the protoplasm in a living cell needs mineral elements like carbon, hydrogen, and oxygen. Nitrogen, sulfur, and phosphorus also take part in the formation of protoplasm.
2. Structure of enzyme: Some mineral elements like magnesium, manganese, cobalt, etc. perform the functions of activators or inhibitors in the system of enzymes. Phosphorus helps in the formation of coenzymes like NAD, NADP, FAD, ATP, etc. Mg, S, and K act as an activator of enzymes.
   • Copper is a component of certain enzymes (i.e. phenolases, laccase, and ascorbic acid oxidases sulfur contains coenzyme A. Calcium is an essential part of amylase, an enzyme that helps in starch digestion. Iron is noted in enzymes like peroxidases and catalases. Manganese helps in the formation of the enzymes decarboxylase and oxidase.
3. Oxidation-reduction reaction: Oxidation is simply regarded as a chemical reaction with oxygen (loss of electrons). The reverse process of loss of oxygen is called reduction. Reaction with hydrogen is also regarded as reduction (gain of electrons).
4. Osmotic balance: Certain mineral nutrients counteract the poisonous effect of some other elements by maintaining the osmotic balance (an ionic balance). The behavior of one ion in reversing the normal effect of another ion is called antagonism. To this group of elements lies Ca, Mg, and K. They are termed balancing elements, whereby osmotic balance is maintained.
5. Formation of Chlorophyll: Magnesium and nitrogen plays a great role in the formation of chlorophyll, the green pigments in plants. Iron takes part in chlorophyll synthesis.
6. Buffer effect: The effect produced when a solution resists change in pH when an acid or alkali is added or when the solution is diluted is called buffer effect (Acid-Base balance).

• • The mineral nutrients play a great role in the pH of all sap. Some of the vital buffer systems in an organism’s body are the carbonate-bicarbonate system and phosphate buffer.

Transpiration

Explanation: Plants absorb large amounts of water from the soil, of which only a small fraction is used for different metabolic functions taking place within their body. The remaining water is liberated in the form of vapor through the leaf, stem, and lenticel using a physiological process termed transpiration.

Transpiration Definition: The elimination of non-utilized excess water in the form of vapor from the plant body, under the influence of sunlight and controlled to some extent by protoplasm is called transpiration.

But evaporation is a physical process in which water changes from a liquid to a gaseous form unsaturated atmosphere from the free exposed surfaces of the living and non-living bodies.

Transpiration is a modified process of evaporation controlled by the protoplasm.

Difference Between Transpiration And Evaporation :

Sites Of Transpiration

There are three types of transpiration based on the organs that are involved in the process stomatal, lenticular, and cuticular pore.

Stomatal transpiration: The loss of water vapor through the openings of stomata is called stomatal transpiration. A major portion (80-90%) of water in the form of vapor occurs through the stomata of leaves.

Lenticular transpiration: The loss of water vapor that takes place through the lenticels (formed during secondary growth on woody stems and fruits) is called lenticular transpiration. The lens-shaped structure lenticel always remains open and helps for the escape of water vapor through the loose mass of complimentary cells.

Cuticular transpiration: The water vapor which is lost through the pore of the cuticle of the leaves directly, is called cuticular transpiration. Some amount (10-20%) of water vapor is lost by direct evaporation from the epidermal cells through the cuticle of the leaves.

Physiological Processes Of Life Difference Between Transpiration And EvaportionTranspiration is affected by several external and internal factors.

For reference only: Using absorptive paper saturated with cobalt thiocyanate transpiration can be experimentally demonstrated. When free from water cobalt thiocyanate paper is blue but when combined with water (moisture) it takes a pink color.

Observe The Fact

Put some amount of water on a dish and observe after a certain period. What you will observe? Can you name that phenomenon?

External Factors:

1. Light: Transpiration increases in the presence of light and decreases in the absence of light, as stomata open during the day and close during the night. Light influences transpiration by increasing the temperature of the leaf.
2. Humidity of air: Under conditions of high humidity, air remains saturated with water vapor, hence it receives less water vapor, thereby reducing the transpiration rate.
3. Temperature: Temperature indirectly affects the transpiration rate by regulating humidity. High temperature lowers humidity, and increases the rate of transpiration, whereas low temperature, increases humidity thereby decreasing the rate of transpiration.
4. Wind Velocity: Wind velocity directly regulates the rate of transpiration. With high wind velocity, the rate of transpiration is high and with low wind velocity, the rate of transpiration is low.
5. Availability of soil water: Transpiration rate depends on water absorbed by the roots, .ess absorption of water causes less transpiration.
6. Atmospheric pressure: Atmospheric pressure affects transpiration. At high atmospheric pressure, the transpiration rate is low and when the atmospheric pressure is low, the transpiration rate is high.

For reference only:

Wilting: Due to inadequate water supply or excessive transpiration in scorching heat, there may be a fall in turgor pressure, so nonwoody parts of the plant (like a leaf, young soft parts, etc.) may dry out, droop, and wither called willing.

Internal Factors:

1. Structure of leaf: The structure of the leaf plays a vital role in storing water that is lost by
   transpiration. Leaf surface area, the total number of stomata, the amount of cuticularisation, the position and number of stomata, the nature of mesophyll cells, and their compactness play a vital role in influencing the transpiration rate.
2. Efficiency of roots: The efficiency of the root system in water absorption also regulates the transpiration rate.
3. Hormonal influence: Cytokinin, Abscisic acid, influences the opening of stomata thereby indirectly controlling the rate of transpiration. The rate of transpiration can be measured by Ganong’s photometer.

Relation between transpiration and ascent of sap: Through the process of transpiration, water goes out of the plant leaf in the form of water vapor through the stomata. Thus volume of water in the leaf decreases and a partial vacuum is created in the plant leaf.

• This vacuum creates a suction pull (suction pressure) that pulls the water column and sap upwards through the xylem vessel from the root through the stem to the leaves.
• This is called transpiration pull. Thus transpiration indirectly helps in the ascent of sap.

Why is transpiration called a ‘necessary evil’: This physiological process is considered to be, “a necessary evil” (Curtis). It is evil as it involves the loss of huge amounts of water, often leading to water deficit in plants, bringing about a reduction in photosynthesis, growth, premature leaf fall, and above all it may also result in dedication and finally the death of a plant.

• These are the harmful effects of transpiration.
• On the other hand, the loss is accepted because the beneficial effect of transpiration (such as osmoregulation, thermoregulation, ascent of sap, etc.) is much more than the harmful effect.
• Hence transpiration is called a necessary evil.

Significance (beneficial effects) of transpiration:

1. Transpiration helps keep the temperature of a plant low (thermoregulation) even when it is exposed to bright sunlight for a long time. It thus prevents the damage of delicate cells,
2. It helps in the distribution of water throughout the plant,
3. Transpiration helps in the translocation of water and minerals through the xylem.
4. Transpiration develops a suction force which is helpful in the ascent of sap and absorption of water from the soil through roots,
5. It helps in giving out excess water (osmoregulation) absorbed by plants from the soil which is not utilized by the plant,
6. It helps in maintaining turgor pressure in the cells and keeps the plant body cool.
7. Transpiration, therefore plays an important role in a plant’s life.

Difference Between Ascent Of Sap And Transpiration :

For reference only:

Guttation: It is the process where water and dissolved minerals are removed from the leaf margin of plants through water pores or hydathodes in the form of liquid droplets.

Difference between Transpiration and Guttation:

Movement Of Water, Minerals, Food And Gases

Introduction: For performing several functions like growth, respiration, excretion, etc. a free movement of oxygen, carbon dioxide, enzymes, vitamins, hormones nutrients, etc., throughout the living body is essential. It is also essential to excrete the toxic substances formed as a result of metabolic activities.

• For all these, a suitable liquid medium is required. There are various circulating media found in the organism, such as water (in plants), blood, and lymph (in animals). Movement of various substances dissolved in the liquid medium throughout the living body is called circulation.
• A living plant body is made up of cells. To survive, all these cells require food, oxygen, water, etc. Substances absorbed or made in one part of the body of the organism are carried to other parts of its body. For this, transport systems are necessary.
• Special tissues or organs are needed. Oxygen for respiration and carbon dioxide for photosynthesis are directly taken by plants from the air by the process of diffusion. The transport system is hence necessary for circulating (conducting) food, water, and minerals.
• The plants have two conducting tissues xylem and phloem. Xylem carries water and minerals, whereas phloem carries food, prepared by the plant itself. In lower aquatic plants water circulation takes place by cell-to-cell osmosis.

Definition of Plant circulation: The process by which the movement of food, water, minerals, hormones, enzymes, and other substances takes place through the liquid medium of the living body by special conducting tissues xylem, and the phloem, is called plant circulation.

The different substances are transported in the plant body using passive transport (diffusion and osmosis) and Active transport.

Medium of transport: Water: It is the chief medium of transport in the plants. Water is absorbed from the soil by the roots.

• In aquatic plants, water is absorbed throughout the body surface.
• The various processes involved in the transportation of different substances in plant bodies are stated below

Passive Transport Features of Diffusion And Osmosis

Diffusion:

Diffusion Definition: The spontaneous spread of molecules of any substance from a region of great abundance i.e. from higher concentration to a region of lesser concentration or nil abundance is called diffusion. It does not need any energy (ATP) for its function, hence this type of transport is passive.

Characteristics of diffusion:

1. Diffusion takes place from higher concentration to lower concentration.
2. During diffusion, both solute and solvent can flow.
3. Diffusion takes place without any membrane or if there is any membrane, it must be a permeable membrane.
4. Diffusion can take place between two liquids, two gases, liquid and gases, solids and gases.

Some common examples of diffusion :

1. Between two liquids: One drop of ink/eosin in a glass of water.
2. Between two gases: One incense stick burns at one corner of the room and the gas molecules spread all over the air of the room.
3. Between liquid and gas: Spraying of perfume and its smell spreads all over.
4. Between solid and gas: The smell of naphthalene spreads all over the box through the air.

For reference only:

1. DP (Diffusion Pressure): Pressure exerted by the diffusible molecules of higher concentration is called Diffusion pressure.
2. DP0 (Diffusion Pressure Deficit): The difference of DP (Diffusion Pressure) of two- solutions having different concentrations is called the Diffusion Pressure Deficit of lower concentrated solution.
3. WP (Wafl Pressure): The pressure exerted on the contents of a plant cell by the cell, the wall that is equal in force and opposite in direction to the turgor pressure is called the wall pressure.
4. HP (Hydrostatic Pressure): The pressure exerted by water molecules of a cell on its cell wall at a given point is called hydrostatic pressure.
5. TP (Turgor Pressure): When a plant cell is fully saturated with water, it is called a turgid condition and the maximum hydrostatic pressure in a turgid condition is called turgor pressure.

Osmosis:

Osmosis Definition: The movement of solvent molecules through a semi-permeable membrane from a region of higher concentration to a region of lower concentration is called osmosis.

• Osmosis is a special kind of diffusion of a solvent through a semipermeable membrane. Water is known as the universal solvent.
• With the help of osmosis, only solvent molecules can pass through semipermeable membranes from a region of higher solvent concentration to of lower solvent concentration.
• For this reason, osmosis is known as the diffusion of solvent molecules.
• if plain water and sugar solution are kept separated by a semipermeable membrane, water molecules From the plain compartment will pass to the sugar solution.

Types of Osmosis: About any living cell,  osmosis may be of two types

1. Endosmosis: The process by which the solvent molecules from outside enter into h – is known as endosmosis.
2. Exosmosis: The reverse process of endosmosis which involves, the exit of solvent molecules from the cell, is known as exosmosis.

Nature of membranes: According to physical properties, the membranes are of three types

• Permeable membrane: Such membrane allows all the molecules or ions of a solution (both solute and solvent molecules) to pass through it, for example, filter paper, cell wall, etc.
• Semi-permeable membrane: Such membrane allows passage of water (solvent) molecules and positively charged hydrogen ions, but not the solute molecules nor the other positively charged and negatively charged particles, for example, air bladder of fish, egg’s membrane, etc.
• The semipermeable membrane can be better termed as differentially permeable, which allows passage of some solutes but, holds back others at different rates of diffusion,
• Impermeable membrane: It does not allow either the solvent molecule to pass example rubber sheet or, a plastic sheet.
• A membrane that permits certain solute and solvent substances to pass through more easily and the other is said to be selectively permeable.

Process of osmosis: If two solutions of different concentrations are separated by a semi- a permeable membrane, then the solvent molecules from the less concentrated solution (which contains more solvent and less solute) move through the membrane to the more concentrated one (which contains less solvent but more solute).

During such movement, the fluid level gradually rises in the compartment containing the more concentrated solution and a position of equilibrium is ultimately reached when the hydrostatic pressure prevents further entry of solvent into this Compartment.

Osmotic Pressure Definition: The molecules of the water inside the compartment of the cell create a pressure known as hydrostatic (HP). The hydrostatic pressure wb\h which develops during osmosis is known as osmotic pressure (OP).

Active transport: Active transport is the movement of lower to higher concentration, which involves carrier molecules and needs energy.

Role of active transport: The theory of transport across the cell membrane was first proposed by Hoagland and others in 1923 while working with Nitella. The mechanism of active transport was studied by Hoagland and Davis.

Active Transport Definition: The transport of matter in the form of ions or molecules across the cell membrane from lower concentration to higher concentration with the expenditure of metabolic energy is called active transport (uphill).

During active transport, the membrane proteins use energy to pump molecules of matter across the cell membrane against a concentration gradient, from low to high concentration. Salt absorption is related to the energy of the cell.

Process of active transport: The process of active transport through carriers involves a sequence of events which are stated as follows :

1. On the outer surface of the cell membrane substrate i.e. ions or molecules bind to membrane protein (carrier),
2. The carrier substrate complex thus formed moves across the cell membrane.
3. Reaching the inner surface of the cell membrane, the carrier substrate complex breaks (dissociates).
4. The molecules or ions are released and enter the cell, The carrier (membrane protein) returns to its original state and is free to accept another ion or molecule.

Cell To Cell Transport

D.Role of osmosis and diffusion in circulation :

1. The unicellular root hairs absorb capillary water of the soil by osmosis.
2. Water then enters the cortical cells of the root by cell-to-cell osmosis, finally carried to the xylem vessel.
3. Minerals in the form of ions reach the cells from the soil by diffusion. Later, water and minerals are mixed up to form the xylem sap.
4. Xylem sap moves upwardly and enters the cells of mesophyll tissue by osmosis and diffusion.
5. Sieve tubes of phloem conduct prepared food formed in the mesophyll cells to different parts of the plant body by diffusion. Thus, the process of diffusion and osmosis plays an important role in the conduction of plants.

Mechanism of absorption and transport of water in plants:

1. Water absorption by plants through unicellular root hairs is facilitated by the process of osmosis.
2. Root cells have higher osmotic pressure than that of external soil solution. Water enters the root hair cells by endosmosis through the cell membrane acting as a semi-permeable membrane,
3. With the entrance of water by endosmosis the root hair cells turn turgid,
4. Osmosis is set up between the cells of the cortex of the root and root hairs,
5. Water enters the cells of the cortex leaving the root hair cells flaccid. These flaccid cells turn turgid by reabsorbing capillary water,
6. This process allows the continuous transfer of water from the soil to cortical cells Cell-to-cell osmosis brings about turgid conditions in all cells,
7. Water is forced to enter the xylem vessels from where it is conducted to other parts of the plant body,
8. The ability of entry of solvent (water) into the cell is determined by the difference between osmotic pressure (OP) and turgor pressure (TP). This is known as suction pressure (SP) or diffusion pressure deficit (DPD).

Difference between Osmosis and Diffusion :

Concept Of Ascent Of Sap Through Xylem (Role Root Pressure And Transpiration Pull)

1. The upward movements of sap from the root region take place through the Xylem (mainly through the Xylem vessel). The upward movement of sap is called the conduction of water.
2. It takes place due to the combined effect of root pressure. Adhesion-Cohesion force and active transpiration pull. For that reason, the water column moves through the xylem vessels which are in a state of cohesion and adhesion.
3. The solution of water containing minerals called sap, commonly known as xylem sap.
4. The process of upward transportation of sap against the force of gravity, from the passage cells through the xylem vessels to the leaves is called ascent of sap.

Factors Affecting the ascent of Sap:

Root Pressure: The pressure exerted by plant sap in the root of the plant is called root pressure. Plants absorb water and minerals with the help of root hairs from the soil. This water along with minerals (sap) reaches the cortex cells by the process of cell-to-cell osmosis and diffusion. Then water

Flows through endodermis, and pericycle and finally reaches xylem vessels. This active hydrostatic pressure created in the parenchymatous cortical cells of the roots is called the root pressure. The sap reaches the stem at a certain height through the xylem vessel.

Adhesion-Cohesion Force:

Adhesion: Adhesion is the intermolecular attraction among dissimilar molecules union between water molecules with the inner xylem vessel

Cohesion: Cohesion is the intermolecular attraction among similar molecules the union between water molecules.

• Water molecules form a continuous chain from the root to the leaf by cohesion pressure or cohesion force.
• Water molecules also exert a sideway pressure on the xylem vessel called adhesion pressure or adhesion force.
• This cohesion-hesion pressure or force keeps the water molecules in position in the xylem and prevents the water column from breaking up.

Transpiration Pull: During transpiration, water is lost from the leaf in the form of water vapor. Thus a partial vacuum is created in the plant leaf, that pulls the water column upwards, known as transpiration pull. This pull helps in the ascent of sap.

• Transpiration creates a pull from above and the continuity of the water column is maintained by the cohesion of water molecules and adhesion of water molecules with the inner xylem vessel wall which prevents the water column from breaking down. Root pressure also pushes the water column upwards.
• Hence ascent of sap is the combined effect of pushing force (root pressure, adhesive-cohesive force) and pulling force (transpiration pull).

Relation Between Absorption And Ascent Of Sap: Unicellular root hairs absorb water and minerals (capillary water and minerals) from the soil.

• This water enters the cortical cells by cell-to-cell osmosis and diffusion. Hydrostatic pressure exerted by these turgid parenchymatous cortical cells helps the water to enter the xylem vessels.
• The transpiration pull from the leaves and the root pressure from below accounts for the ascent of sap through the xylem vessels.
• The continuity of the water column is maintained by the cohesion of water molecules with each other and the adhesion of water molecules with the xylem vessel wall.

Characteristic features of Transportation of Food through Phloem

Plants synthesize carbohydrates, a type of food matter in the green parts and in the chlorophyll-bearing regions, mainly in leaves. Food prepared in these areas has to xylem phloem be transported to all the parts of the plants through the interconnected phloem tubes.

Translocation Definition: The transport of food through phloem tissue in plants is called translocation.

1. Sieve tubes, the non-nucleated living cells of phloem, are responsible for carrying food by translocation,
2. The companion cells with dense cytoplasm and prominent nucleus are also indirectly associated with the sieve tube for such conduction,
3. The sieve plates (end walls of the sieve tubes) are perforated by sieve pores.
4. The protoplasmic connections (Plasmodesmata) passing through the sieves take part in the conduction of food materials
5. Food is also carried to the growing regions and storage regions like fruit, stem, root, etc.

For reference only: During active growth or in times of energy requirement to run the different vital functions, the stored food is hydrolyzed for transport through the phloem to growing regions of the plant body.

Difference Between Upward Circulation And Downward Circulation :

Movement of gases i.e Exchange in Plants

For reference only:

Photosynthesis in plants involves intake of carbon dioxide and disposal of oxygen. During respiration plants use oxygen and give out carbon dioxide. In plants, there are no respiratory organs.

• The elaborate liquid transport system cannot be used in the transport of gases.
• The leaves are well adapted to carry out gaseous exchange during photosynthesis.
• The rate of respiration in the roots, stems, and leaves of plants is lower than that of animals.
• In the leaf and stem of plants, the living cells are located close to the surface.
• The loosely arranged parenchyma cells with intercellular spaces in leaves, stems and roots provide an interconnecting system of air spaces.
• The diffusion of gases is faster through the air than through water.
• So diffusion of oxygen and carbon dioxide takes place rapidly through the interconnecting system of intercellular air spaces.
• These gases also pass through the cell wall and plasma membrane by a diffusion process.
• Aquaporin channels in the plasma membrane help in diffusion across the membrane.

Absorption of gases by Leaves: Gaseous exchange in leaves takes place through stomata when light falls on a leaf. These openings remain open in the morning and close during the night.

• This happens due to a change in the turgor pressure of the guard cells. Guard cells possess a thick and elastic inner wall.
• When turgor pressure develops the outer thin wall of the guard cell extends out forcing the inner walls into a crescent shape, resulting in the opening of the stoma.
• Again, loss of turgor pressure causes inner walls to regain their original shape resulting in the closing of the stoma.
• During the day when osmotic pressure in the lower epidermal cells remains constant and the osmotic pressure of guard cells increases then the stomata open.
• In the evening stomata closes when the osmotic pressure of guard cells drops to nearly that of surrounding cells.

Absorption of gases by Roots and Stems: The dead cork cells present in mature roots and woody stems contain suberin (a waterproof substance) which makes the cork impervious to oxygen, carbon dioxide, and water.

Activity:

Take a fresh Balsam plant out of the soil with an intact root system. Fill 3/4^th of the conical flask with water. Add a few drops of eosin dye into water.

• The water turns red. Place the Balsam plant in the conical flask in such a way that the roots only remain submerged in water.
• Keep the experimental setup in this position for an hour.
• Observe the setup after an hour and note down your observation.
• Cork of mature roots and woody stems contain non-suberized perforated pores called lenticels which allow entry to oxygen to reach
• The intercellular spaces of interior tissue and CO₂ are released into the atmosphere.
• Stems of many plants are green in color and use stomata for gas exchange rather than lenticels.

Organ-level Respiration (Respiratory Organs)

Organism Definition: Respiratory organs are the specific type of organs that help the process of exchange of gases, O_2, and C0₂ between the environment and the organism.

Characteristic features of respiratory organs :

1. The respiratory membrane must be thin and permeable so that it is easily gaseous. exchange.
2. The respiratory surface must be extensive to provide a greater surface area for gaseous exchange.
3. The respiratory organ must be always kept moist to facilitate the diffusion of gases.
4. In higher animals, the respiratory organ is highly vascularised so that blood can transport respiratory gases) from respiratory organs to different cells of the body and vice versa for CO₂.

Now, can you explain why the skin of a toad acts as a respiratory organ but not the skin of a many)

Respiratory Sites of Plants

Stomata: These are microscopic apertures in the leaf epidermis of plants guarded by two semi-circular guard cells. Stomata are generally present on the ventral surface in monocot plants. Through the opening of stomata gaseous exchange takes place.

Lenticels: Lenticel is a porous tissue consisting of cells with large cells with intercellular spaces, generally on the bark of woody stems of dicot plants. It functions as a pore that provides a pathway for direct exchange of gases between the internal tissues and atmosphere through the bark. (Tough thick bark is otherwise impermeable to gases)

Pneumatophores: These are breathing roots, found in mangrove trees and they are negatively geotropic adventitious branches of the root. In fact in saline soil, the capillary space of the soil is almost blocked by a huge deposition of NaCI. So there is less capillary air hence the root suffers from O₂ deficiency. So, some of the adventitious roots provided with pores bend upward and come above the soil surface to absorb O₂ directly from the air. Example pneumatophores in Sundri Plant.

Respiratory Organs Of Animals

Introduction: Usually, respiration in different animals is performed by the definite organs called respiratory organs. In lower animals, the exchange of gases takes place through the body surface, whereas in higher animals, there are complex organs like trachea, lungs, etc. The following is a brief account of the different types of respiratory organs found in different animals.

Respiratory Organs Of Different Animals

1. Body surface i.e., cell membrane Amoeba, Sponge, Poramoecium, Hydro.
2. Moist skin Earthworm, Leech.
3. Skin, lungs, buccal cavity Toad
4. Trachea Insect, Cockroach, Grasshopper.
5. Gill Fish, Mollusca, Prawn, Crab.
6. Labyrinthine organ, gills Koi fish.
7. Respiratory tube, gills Singhi fish.
8. Lungs Whale, Lizard, Crocodile, Mammal.
9. External gills Tadpole.
10. Book lungs Scorpion, Spider.
11. Book gill King crab (Limulus)
12. Lungs, 9 air sacs Pigeon

Body surface: In the case of aquatic animals like Amoeba, Sponges, Poramoecium, Hydro, etc. exchange of gases between cells and their environment takes place by simple diffusion through the cell membrane (body surface).

Skin: Terrestrial animals like earthworms, leeches, etc. respire partly or wholly through thin and highly blood-supplied moist skin.

Do you know that in Toads or Frogs, there are three respiratory organs: Lungs (Pulmonary respiration) in normal conditions; Skin (cutaneous respiration); in hibernation as well as in normal conditions also; inner wall of the buccal cavity (buccopharyngeal respiration) mainly v during ingestion of food.

Trachea: Insects and varieties of Arthropods have elaborate networks of air-filled tubes called trachea which open onto the body surface through the small pores called spiracles or stigmata. (Do you know there are 10 pairs of spiracles in Cockroach ?) The trachea branches repeatedly into tubes called tracheoles through which gaseous exchange takes place.

Try to write the comparison between stomata and stigmata.

In insects, blood does not carry 02 because 02 is directly carried to different cells of the body through the trachea.

Gills: In aquatic animals like fish, external respiration takes place through gills. These are specialized structures of dark color, provided with thin walls and blood capillaries

• which favors easy diffusion of gases between dissolved 02 in water and the circulating blood passing through them. The actual site of gaseous exchange in fish is the gill lamella of the gill filament.
• Do you know that besides fishes, so many other animals breathe by gills Example Snails (Mollusca), Prawns (Arthropoda), and so on?
• Try to find out in which animal the respiratory organ is book gill. What is the respiratory organ of spiders and scorpions?

Accessory respiratory organs Definition: The organs that partly accomplish respiration and are additional complementary respiratory structures are called accessory respiratory organs (other than gills). Some jewel fishes like Koi, Magur, and Singhi are provided with these organs.

• Accessory respiratory .organs develop in addition to the normal pharyngeal gills, to help the fish live in aquatic environments with low oxygen
• concentration or to breathe oxygen directly from the air, aestivate (summer sleep) over prolonged droughts during summer, and meet the extra demand for oxygen.
• However, accessory respiratory organs in fishes can perform gaseous exchange so long as they remain moist.
• Gills are incapable of utilizing oxygen in the air, so accessory respiratory organs are useful adaptive features of some fishes.
• These fishes that possess these adaptive features are called jellyfish. Now you can understand why the jeol fishes can survive on land for a long time.

Structures Of Accessory Respiratory Organs :

1. In Koi (Anabas testudineus): The presence of a labyrinthine organ located within the cavities of the gill chamber. It is rose-shaped and covered by epithelium having numerous blood vessels.
2. In Magur (Clarius batrachus): Presence of tree-like dendritic or arborescent organ located within suprabranchial cavities of the gill chamber.
3. In Singhi (Heteropneustes fossilis): The presence of long tubular dorsally situated respiratory tubes or air sacs arising from the gill chamber and extending up to the tail.

Lungs: Lungs are the specialized respiratory organs of all land vertebrates Example, birds (pigeons), reptiles (lizards, snakes), amphibians (frogs, toads), ‘and mammals (rats, cows). Aquatic mammals (For example whale, dolphins) are also provided with lungs.

• That is why some animals (Whales, dolphins, and Crocodiles) often come above the surface of the water for aerial respiration.
• The lungs of amphibians, reptiles, and mammals are paired sac-like spongy structures due to the presence of air-filled alveoli.
• Alveoli are provided with numerous blood vessels (capillaries) for gaseous exchange.
• The lungs of pigeons are more compact and are supplemented by thin-walled 9 air sacs for storage of air that also help to increase buoyancy.
• Air sacs can store air only but no gaseous exchange. Gaseous exchange occurs only in the lung alveoli of pigeons.

Do you know there are nine major air sacs and four minor (accessory) air sacs in pigeons?

Lungs in man: Two reddish sponge-like lungs are situated in the thorax above the diaphragm. Each of the conical lungs is enclosed in a double-layered membranous sac, called pleura.

• A small amount of serous fluid (pleural fluid) is present in the closed pleural cavity.
• The right and left lungs are divided into 3 and 2 lobes, respectively. Inside each lung, the primary bronchi divide and subdivide into many terminal bronchioles.
• Each of them leads to several alveolar ducts.
• Each alveolar duct opens into many small, thin-walled sacs, called alveoli. Around each alveolus, blood capillaries form a network.
• The exchange of gases takes place between the blood in these capillaries and the air inside the alveoli.

Lungs and breathing in human

The process of breathing in man is completed in two phases Inspiration and Expiration.

Inspiration: The active process by which air from the atmosphere enters into the lungs is known as inspiration.

Expiration: The passive process by which air from the lungs is expelled into the atmosphere is called expiration. Organs involved in Inspiration and Expiration are mainly the diaphragm and intercostal muscles.

Diaphragm: It is a dome-shaped sheet of unpaired internal skeletal muscle that separates the thoracic cavity from the abdominal cavity.

Intercostal muscle: The muscles which remain obliquely in between ribs are known as intercostal muscles.

The process of breathing in man is accomplished by coordinated movement of diaphragm and intercostal muscle as follows :

Try to discover what happens during forced inspiration and forced expiration.

Lungs And Healthy Life

Breathing exercise plays a very significant role in increasing lung volume. Decreased lung capacity can negatively affect quality of life.

• Athletes, singers, dancers, and other health-conscious individuals also practice various methods to improve lung capacity. Specific exercises can help to increase lung volume and its elasticity.
• A deep breathing technique for increasing lung capacity is called “Mother Breath”. This exercise can be done by slow inhaling for seven seconds.
• The breathing is to be held for a few seconds and then slowly exhaled for seven seconds. The sequence may be repeated. This is just an example. There are, however, many more techniques.
• There are different breathing exercises in “Pranayam”, which help to improve the function of the heart and lungs. However, someone must be cautioned not to do any breathing exercises on a full stomach i.e. after lunch or dinner. It should be practiced on an empty stomach preferably in the early morning after getting up from bed.
• You have heard of “Laughing Club” where so many people together practice lung exercises in the early morning. They have some definite guidelines for practice. Try to practice lung exercise regularly.

Cigarette Smoking Is Harmful For Respiratory System: Cigarette smoke contains innumerable constituents of which almost all of them are harmful, toxic, poisonous, and badly carcinogenic (that induces cancer) to the respiratory system.

• Some serious diseases of the respiratory system are associated with smoking like Cancer, Bronchitis, Emphysema as well as Cardiovascular disorders, and so on.
• Millions of smokers all over the world are dying of Cancer every year.
• Try to create awareness among people in your locality about the dangers of smoking.
• Have you heard the term “active smoking” and “passive smoking?

Cellular Respiration

Concept Of Cellular Respiration

What is Cellular Respiration: Definition: Cellular respiration is the oxidative, catabolic, enzymatic breakdown of organic substances when potential energy is released in the form of kinetic energy.

AH, organisms require energy to maintain the vital functions of the body. This energy is derived from the food they take.

• During photosynthesis, solar energy is fixed in food as potential chemical energy. This food is used as a cellular respiratory substrate which is oxidized to release energy.
• In the presence of O₂ (aerobic respiration), there is complete oxidation of food that results in a greater amount of energy release whereas in the absence of O₂ (anaerobic respiration), there is incomplete oxidation of food that yields less energy.
• However, the energy released by cellular respiration is stored temporarily in ATP (Adenosine Triphosphate). This ATP (energy currency) is broken to release energy for various activities of the body.

Respiration: A catabolic process: Respiration is called a catabolic process due to the following reasons

1. Respiration is a destructive process, where respiratory substrates such as carbohydrates, proteins, fats, and organic acids are broken down into simpler products with the help of enzymes in different metabolic processes in the body.
2. The process results in a decrease in the dry weight of an organism.
3. The stored energy of food i.e., potential energy is converted to released energy, i.e. kinetic energy.
4. Simpler substances (micromolecules) are formed from complex substances (macromolecules).

Cellular Respiratory substrate: Those protoplasmic substances which when oxidized liberate energy, are called the respiratory substrates. Although carbohydrates, proteins, fats, and organic acids are used as respiratory substrates, carbohydrates, particularly glucose are the chief energy-yielding substrate.

1 gram Carbohydrate     Yields    4.0KCal energy

1 gram protein               Yields     4.1KCal energy

1 gram fat                      Yield        9.3Kcal energy

Time of respiration: In every living cell the process of respiration takes place throughout the whole day and night.

Respiration and Combustion :

• Respiration Definition: It is a biochemical process that takes place in each living cell either in the presence or in the absence of oxygen. During respiration mainly the glucose molecules are slowly oxidized step by step by the action of several enzymes. The energy thus released from the oxidation of sugars is transformed into the energy-rich compound called ATP. Thus respiration may be a controlled burning process (combustion) within the living cells, or controlled cellular combustion that is controlled by the action of various enzymes.
• Combustion Definition: It is a physio-chemical process that takes place in nonliving objects. Only in the presence of oxygen, these objects are burnt violently which produce generally light, heat, and ashes. No enzyme is required for this process. Thus combustion may be called a physico-chemical process by which any substance outside the body is oxidised in the absence of enzyme but in the presence of oxygen and produces heat and light.

Difference between Respiration and Combustion :

Do you know, that fireflies can produce light known as bioluminescence? Is it combustion or respiration?

Types Of Cellular Respiration (Aerobic Anaerobic And Fermentation)

Respiration is mainly of two types, depending upon the nature of oxidation of the substrates i.e., aerobic respiration and anaerobic respiration. Another type of biochemical process occurs in the micro-organism which is called fermentation.

Aerobic Respiration Definition: Aerobic respiration is the process by which complete oxidation of the respiratory substrate (glucose) takes place in the presence of free oxygen, producing end products like C02 and water, with the generation of energy.

In the living cell oxidation of substrate takes place in two ways i.e., either by removal of hydrogen or by addition of oxygen. In aerobic respiration, the molecular or free oxygen is used as an electron or hydrogen acceptor in its oxidative process.

Occurrence: Aerobic respiration takes place in the living cells of all the aerobes (organisms that require oxygen).

Process Of Oxidation And Production Of Energy: In the living cell, aerobic respiration is completed in three stages Glycolysis the first stage, Krebs cycle the second stage, and Terminal oxidation (ETC) the third and final stage.

Can you explain why the rate of breathing increases while playing football?

• Anaerobic respiration Definition: Anaerobic respiration is the process of incomplete oxidation of the respiratory substrate (mainly glucose) in the absence of free O₂ or the presence of bound O₂forming CO₂ and ethyl alcohol (in plants) or lactic acid (in animals) with partial release of energy.
• Occurrence: Anaerobic respiration is a special method of respiration that generally takes place in anaerobic bacteria (For example Clostridium, Lactobacillus), unicellular fungi (Yeast), and in plant seeds during germination, parasitic animals like tapeworm [Taenia solium), roundworm [Ascaris lumbricoides), Monocystis, etc.), in the skeletal muscle fibers (cells) during vigorous exercise, etc.
• Process of oxidation and production of energy: Anaerobic respiration occurs in the anaerobes, an organism that can live without oxygen. Thus in the cytoplasm of anaerobes, one molecule of glucose (C₂H₁₂O₆) is transformed into two molecules of pyruvic acid (C₃H₄O₃).

1. In some anaerobic bacteria like Thiobacillus, methane bacteria, etc. glucose [in the absence of free oxygen, but in the presence of bound oxygen present in chemical compounds like nitrate ‘ (NO₃-), carbonates (CO_3-), sulfates (SO₄+)], gets incompletely oxidized to form carbon dioxide (CO₂), water (H₂O) and energy.
2. The energy released in the process is less, due to the very short phase of terminal respiration. The overall chemical equation is stated below :

Glycolysis is the common phase of both aerobic and anaerobic respiration.

Difference between Aerobic and Anaerobic respiration :

Fermentation :

Fermentation Definition: Fermentation is the chemical process that involves decomposition of the complex organic substances into simpler ones and is brought about by the catalytic influence of the enzyme.

Occurrence: The process of fermentation takes place in the carbohydrate solution (glucose, sucrose, etc.). The organisms causing fermentation are yeast (fungus), Lactobacillus (a bacterium), germinating seeds, etc.

Process of oxidation and production of energy: Different types of fermentation are found in various organisms. Some common examples are mentioned here :

In animal cells: In the sarcoplasm (cytoplasm) of the muscle cells (sarcomere) the pyruvic acid is reduced to lactic acid and yields a small amount of energy in the presence of lactic Dehydrogenase(LHD) (reducing enzyme).

In the plant cell: The pyruvic acid in the presence of certain enzymes is partially oxidized into carbon dioxide, and ethyl alcohol and yields a small amount of energy.

In yeast cells (Alcoholic fermentation): Alcoholic fermentation is the extracellular anaerobic process that occurs with the help of the zymase enzyme of yeast, where glucose: is decomposed into ethyl alcohol and CO₂ with the release of a certain amount of energy. Zymase

Economic importance of fermentation :

1. Alcohol is useful in the wine industry, preparation of different medicines, tonics, biochemical; medicinal research, biological experiments, cosmetics, etc.
2. Vinegar contains acetic acid which is produced by the acetic acid fermentation of Acetobacter bacteria.
3. Curd contains lactic acid which is produced by lactic acid fermentation of lactobacillu bacteria.
4. Lemon squash contains citric acid which is produced by citric acid fermentation of citrobacter bacteria.

For reference only:

Putrefaction and Fermentation

Putrefaction— It is the process of decomposition of organic materials, especially the anaerobic splitting of proteins by microorganisms. As a result, incompletely oxidized and ill-smelling compounds are produced.

Fermentation— It is the process of decomposition of complex organic compounds into simpler ones in the presence of microorganisms in living cells. It is brought about by the catalytic influence of the non-living highly complicated nitrogenous compounds known as enzymes. As a result, organic substances, waste gases, and heat are produced.

Difference between Anaerobic respiration and Alcoholic fermentation :

Steps Of Cellular Respiration And Cellular Sites Where They Occur

As mentioned earlier, there are three essential steps of cellular aerobic respiration: the first stage—Glycolysis, the second stage—Krebs cycle, and the third and final stage-Terminal Steps of glycolysis Respiration (ETC- Electron transport-chain).

Stage 1. Glycolysis

Glycolysis Definition: Glycolysis is an anaerobic oxidative process by which the glucose, in the presence of certain enzymes in the cell cytoplasm, is converted into pyruvic acid.

Different steps of glycolysis were discovered by three scientists  Embden, Meyerhof, and Parnas. According to the first letter of their name, glycolysis is also known as the EMP pathway.

During glycolysis, no free O₂ is needed so this is an anaerobic process. During glycolysis, there is a loss of Hydrogen so this is an oxidative process.

For reference only: Steps 1, and 3,10 of glycolysis are irreversible.

Site of glycolysis: Cytoplasm (outside mitochondria)

End products of glycolysis : 2 molecules of pyruvic acid + 2 molecules ATP + 2 molecules NADH2 (NAD = Nicotinamide Adenine Dinucleotide)

Stage 2. Krebs cycle

Krebs cycle Definition: It is the cyclic, aerobic, oxidative, biochemical pathway that occurs in mitochondria where the cycle starts from citric acid and through different enzymatic steps ends in oxaloacetic acid.

Site cfXrebs cycle: Mitochondria

End products of Krebs cycle: 2 molecules CO₂ + 2 molecules H₂O + 3 molecules NADH^– – 1 molecule FADH- I molecule ATP.

1. Alternate names of Krebs cycle: In 1937 the famous English biochemist Sir Hans Adolf Krebs first discovered this pathway.
2. Thus according to his name, the cycle is called Krebs cycle. the first product of this cycle is Citric acid, thus Krebs cycle is also known as the citric acid cycle.
3. The first formed acid (citric acid) contains three carboxyl – COOH; groups, hence it is also known as the tricart: acid cycle or in short TCA cycle.

For reference only:

In the Krebs cycle, there are three irreversible steps

Stage 3: Terminal Respiration (ETC/ETS-Electron Transport chain or system) This is the last stage of aerobic respiration that follows the Krebs cycle.

• This process also occurs in mitochondria.
• This step consists of several electron carriers through which electron moves sequentially and ultimately to molecular oxygen at last.
• Electron comes from NADH₂ and FADH₂ formed in glycolysis and Krebs cycle.

Now can you compare cellular respiration and breathing?

Significance Of Respiration

Release of Energy: Respiration is an energy-producing process. During photosynthesis, solar energy is stored as potential energy within the foodstuff. During respiration, this potential energy is converted into kinetic energy (i.e. released energy).

• Some amount of energy released during respiration is conserved and stored as ATP (a high energy-rich organic compound) in the mitochondria for future uses. This energy is used to perform various life processes in the living organism.
• The rest of the energy is released as heat energy to maintain the body temperature.
• Do you know—The light, which radiates from the glow-worm and some sea animals (bioluminescence) is a form of energy produced during respiration.
• Have you heard the term— Luciferin?
• The electricity which is produced from the electric ray fish is also a form of energy produced during respiration.
• The daily calorie requirement of an adult is 2500—3000 Kcal. It is obtained from ATP, produced during respiration.

Maintenance of oxygen (O₂) and carbon dioxide (CO₂) balance: The approximate normal percentage of O₂ and CO₂ in the air is 20-4% and 0-03% respectively. During photosynthesis, the plant body utilizes CO₂ and releases O₂.

• This may cause an increase in O₂ and a decrease in CO₂ in the atmosphere, but it does not happen.
• Because during respiration the living organism takes O₂ and releases CO₂.
• In this way, the process of respiration maintains an O₂—CO₂ balance in the environment.

Differences between Cellular Respiration and Breathing :

Differences between Photosynthesis and Respiration :

Concept of Nutrition

Introduction: All living organisms require food. II. Is needed for growth, movement, reproduction, energy production, healing and repair, disease resistance, and so on.

• A living organism either synthesizes or collects Its necessary food from the environment. The food may be utilized directly or indirectly.
• The process involved in the conversion of complex food into simpler products or products is termed digestion.
• The digested product (or products) is absorbed within the body and is transformed into constituent(s) of protoplasm by the process of assimilation.
• In addition to energy-yielding food like carbohydrates, proteins, and fats, minerals, vitamins, and water are also required for various life processes, All these essential substances are collectively called nutrients.

What is a nutrient?

The organic and inorganic materials that the living organism collects from nature to perform all the fundamental activities of the body are called nutrients, for protein, fat, carbohydrates, vitamins, minerals, and water.

Significance Or Importance of nutrition :

1. Growth promotion, repairing wear and tear of the damaged tissues, and gaining energy to control the different metabolic processes are the main functions of nutrition.
2. The potential energy stored within food is transformed into usable energy through nutrition.
3. The different physiological functions of the living body like movement, locomotion, excretion, reproduction, etc. are controlled by utilizing this energy.
4. Nutrition helps to develop the disease-resistant power of the living body.
5. Nutrition helps to store food in the body for future use. From those stored foods (in the plant body mainly as starch and in animals as glycogen or animal starch and fat) the future energy is produced during a shortage of food.
6. Nutrition plays a special role production of heat energy in the organisms to meet the caloric demand.

Can you explain the relation between malnutrition and frequent infection in the body? Explain in which tissues of the human body food is generally stored.

Malnutrition

A state of abnormal nutrition, that is caused by an insufficient or unbalanced intake of the basic nutrients or their impaired assimilation and utilization by the body is called malnutrition.

Types of Nutrition

Plant Nutrition: Plant nutrition is of two types Autotrophic plant nutrition and heterotrophic plant nutrition. The two phases of plant nutrition are synthesis and assimilation. The preparation of organic food matters is called synthesis and the incorporation of simple food matters within the protoplasm for different metabolic functions is called assimilation.

In autotrophic nutrition, plants obtain simple, inorganic food elements, in the form of liquid (H₂O) and gases (CO₂) and produce organic food matters, this type of nutrition is called holophytic nutrition.

Autotrophs and Heterotrophs:

Autotrophs Definition: Plants that possess chlorophyll and can prepare their food from CO₂ and H₂O in the presence of sunlight are called autotrophs.

Examples are green plants, Neem (Azadirachta indica), Mango [Mangifera indica), epiphytic plant Vanda (B. Rasna), etc.

Heterotrophs Definition: Plants that depend on other host plants or dead decaying organic matter for nutrition are called heterotrophs.

Examples—Fungi—Mucor, Agaricus.’

Different types of Heterotrophic plant nutrition: The nutrition in heterotrophic plants is called heterotrophic nutrition.

Parasitic Nutrition Definition: The process by which plants obtain their necessary nutrition from any other living plants or animals of different species (host) is called parasitic nutrition. Plants drawing in nourishment are called parasites and from which nutrients are drawn in are called hosts. Parasitic plants generally suck in the nutrients by haustoria or sucking roots from the host body.

Total Parasite or Holoparasite—Plants that draw their total nourishment from their respective hosts. Examples: Total stem parasite Example Cuscuta refiexa (dodder, swarnalata). Total root parasiteExample Balanophora dioica, Rafflesia Arnoldi (Largest flower in the world).

Partial parasite or Semi-parasite— Plants that can prepare food as they contain chlorophyll, but are dependent on the host plants for water and minerals. Examples Partial stem parasite Example Viscum album, Loran. thus longiflorus. Partial root parasite  Example Santalum album (B. Chandan).

Some Notes On Parasitic Nutrition

Parasitism: Parasitism is a close association between two living organisms of different species which are beneficial to one (to the parasite) and harmful to the other (to the host). The parasite obtains food from the host and generally takes shelter.

Ectoparasites: The parasites that live on the outer surface of a host. Examples are Head lice, ticks, fleas, leeches, and phytophthora (fungus causing disease in potatoes).

Endoparasites: The parasites that live within the host. Examples are Plasmodium (a parasite that causes malaria), the tapeworm Taenia, and Swarnalata.

Saprophytic Nutrition Definition: The nutrition of certain non-green plants that draw their nourishment from the dead and decomposed organic substances formed as a result of the decay of plants and animals is termed saprophytic nutrition.

Total saprophytes: Saprophytes dependent fully on dead decaying organic substances for their nutrition are called total saprophytes. Examples: Total saprophyte Mucor, Penicillium, Agaricus, Monotropa uniflora (devoid of roots and chlorophylls).

Partial saprophytes: Green plants that depend partially on dead decaying organic matter for nutrition are called partial saprophytes. Examples: Partial saprophyte Pinus (they absorb organic substances with the help of certain fungus(mycorrhiza) growing on their roots.

Difference Between Parasite And Saprophyte :

Differences Between Parasite And Symbiotic Nutrition:

Symbiotic Nutrition: When two different species of organisms live in close association with each other for their mutual benefit in nutrition and shelter, the type of nutrition is called symbiotic nutrition. Each of the pair is called symbiont and the mode of their association is termed symbiosis.

• Examples: Symbiosis between bacteria and plant: Rhizobium leguminosarium residing in the root nodules of leguminous plants are capable of fixing atmospheric nitrogen forming nitrate and supplying it to the plant. In return, the plant provides carbohydrate food and shelter to the bacterium,
• Symbiotic association between plants and animals exists between  Zoochlorella and Hydro, Lichen an association between an alga and a fungus (Symbiosis between plant and plant).
• The fungus protects the photosynthetic organism while algae prepare food by photosynthesis, which is shared by fungus. Thus both algae and fungal components are mutually beneficial.

Insectivory (Nutrition of insectivorous plants) (Carnivorous plant): Some green plants that are unable to draw nitrogenous nutrients from soil secure the same from insects. These plants are called insectivorous plants. The process of nutrition by which these plants take in insects and digest the protein part within the body with the help of certain enzymes is called insectivorous nutrition.

Examples: Pitcher plant (Nepenthes khasiana) Here the leaf blade is modified into a pitcher and the leaf apex into a lid. On the inner wall of the pitcher, some glands attract the insects. When the insect moves in, the lid.is closed, the insect is trapped and the body fluid of the insect is sucked in by the pitcher.

Imagine What Will Happen When The Pitcher Will Be Full Of Dead Bodies Of Insects:

 

Bladderwort (Utricularia stellaris): The leaf of this rootless aquatic plant is modified into a bladder-like structure and is supplied with a valve, that opens inwardly. The inner wall of the bladder bears digestive glands. It is a rootless aquatic insectivorous plant.

Sundew (Drosera indica): The upper surface of the leaf blade contains hair and glands secreting a sticky fluid to which insects get entangled.

Venus fly trap (Aldrovanda vesiculosa): A rootless aquatic plant that bears leaves with two halves. Sensitive trigger hair and digestive glands present on the upper surface of the leaf serve as a trap for insects.

Difference between Autophyte and Heterophyte :

Animal Nutrition :

Animal Nutrition Definition: Animals are mostly heterotrophic and their nutrition is commonly known as holozoic nutrition where the animal ingests liquid or solid organic material.

Parasitic nutrition definition: An animal parasite is an animal that depends on the host body of different species for food and shelter causing harm to the host. This type, of nutrition, is called parasitic nutrition, Example Ascaris (Roundworm) is a parasite in the human intestine, Taenia solium (Tapeworm) is a parasite to the human intestine; Plasmodium (malarial parasite) is a parasite to human RBC and liver, etc.

Symbiotic nutrition (Mutualism) Definition: When two different species of organisms live together for the mutual benefit of nutrition it is called symbiotic nutrition and each of the species is called a symbiont.

Examples:

• The symbiosis between animal and plant: Green Hydra and Zoochlorello (alga) living together where green Hydra provides protection and shelter to Zoochlorella. In turn, Zoochlorella performs photosynthesis and provides O₂ to Hydra.
• Symbiosis between animal and protozoa: Termites feed on wood but they do not contain cellulase enzyme. In the digestive system of termites, there are a large number of flagellate protozoa named Trichonympha that can produce the enzyme cellulase which helps in the digestion of cellulose. Thus termites provide shelter to protozoa and protozoa provide cellulase to termites so both of them are mutually beneficial.
• Symbiosis between Ruminant mammals and bacteria: Ruminant mammals also need cellulase enzyme for digestion of cellulose which is produced by symbiotic Rumenococcus bacteria, who get food and shelter, in turn, from cattle.
• Saprozoic nutrition  Definition: The nutrition where an animal gets its nutrients from decaying organic matter after digesting it with the help of exoenzyme is called saprozoic nutrition.Example.Housefly, Earthworm. Nematodes, etc.
• Coprophagy  Definition: In rabbits, guinea pigs, etc., cellulose is digested in the large intestine where cellulase enzyme is released from the caecum (cellulase is synthesized by symbiotic cellulolytic bacteria in the caecum). This digested but unabsorbed cellulose goes out of the body through the rectum and anus, which is reingested by mouth. These digested cellulose droplets are softer and lighter having no smell and are directly eaten from the anus sometimes. (The actual fecal stool droplets are harder having a bad smell, that is egested from the body).
• Sanguinivory  Definition: The animals who live on sucking blood from the body of other organisms are called sanguinivorous animals, Example. Mosquitoes are sanguinivorous as they suck blood from others; Leech sucks blood from cattle and other animals including man; vampire bat sucks blood (Haematophagy) of mammals.

Difference between Plant Nutrition and Animal Nutrition :

Do you know that Euglena is no longer considered an animal but is considered a Protista?

However, they contain chlorophyll and can perform photosynthesis.

Steps Of Holozoic Nutrition And Associated Parts Of The Alimentary Canal In Huma

Holozoic nutrition in man is completed in five stages and different organs are involved in each stage as follows:

Step 1: Ingestion: The process by which food is taken in the body of man is called ingestion. Associated organs Teeth, Tongue, Lips, and Hand.

Step 2: Digestion: The process by which insoluble, unabsorbable, macromolecule of food is broken into soluble, absorbable, micromolecule by the action of different enzymes is called digestion. Associated organs: Mouth, stomach, small intestine, and different digestive glands like salivary gland, gastric gland, pancreas, Intestinal gland, liver. The gland secretes digestive juice-containing enzymes.

Step 3: Absorption: The process by which soluble micromolecules of food are taken into the lymph or bloodstream of the body is called absorption. Associated organs Lymph vessels (Lacteals) and blood vessels of the villi of the small intestine mainly. Lacteals are the lymph capillaries in the intestinal villi.

Step 4: Assimilation: The process by which the absorbed food materials are incorporated into protoplasmic substances of body cells as well as some extracellular materials is called assimilation. Associated organs cells, tissues, blood, and extracellular fluid of the body.

Step 5 : Egestion: The process by which undigested and unabsorbed materials go out of the body is called an egestion. Associated organs  Colon, Rectum, and Anus.

Do you know?

Sometimes, transportation is considered a step of holozoic nutrition. Transportation is more a part of circulation which is related to nutrition for the distribution of absorbed food materials all over the body. Can you explain why is the stool commonly yellowish in color?

Components Of Alimentary System And Their Role In Nutrition

Alimentary (Digestive) System Definition: The system concerned with the intake, digestion, and absorption of food and the elimination of unabsorbed food from the body is known as the digestive system.

Structure: The alimentary system consists of the alimentary canal and several accessory or associated organs.

How can you compare the alimentary system to land digestive system?

Alimentary canal: Alimentary canal is a tube-like structure whose diameter is modified ( changed) in various parts of it. It is an open tube that begins at the mouth cavity and ends in the anus.

Mouth: It contains mainly tongue and teeth. The mouth is a cavity bounded by muscles other soft tissues and bones. It communicates with the exterior through the oral aperture between the lips and opens behind the pharynx.

Tongue: The muscular tongue, attached with hyoid and mandible bones. It is located on the floor of the mouth and bears many tiny projections known as papillae on its upper surface. Taste buds are present in some of these papillae.

Teeth: In each jaw bone of an adult, 16 teeth are lodged inside the tooth socket. These are called permanent teeth which consist of the following types 4 incisors, 2 canines, 4 premolars, and 6 molars. The child, on the other hand, may carry only up to 10 teeth in each jaw (a total of 20 teeth); these are called deciduous teeth or milk teeth and are later replaced by permanent teeth. Therefore dental formula in adult men is 12⁄2, C1/1, PM2/2, M3/3

1. Salivary glands: Three pairs of salivary glands are present near the mouth. They secrete salivary juice (saliva).
2. Pharynx: Pharynx is a broad funnel-shaped cavity of about 10-12 cm long and lies behind the mouth. It serves as a common passage for both the alimentary tract and the respiratory tract. The mouth cavity, the nasal cavity, and the two eustachian tubes coming from the two middle ears, all open into the pharynx. The pharynx opens into the esophagus.
3. Oesophagus: Oesophagus is a long narrow about 25 cm long tube. It is continuous with the pharynx above and passes through the thorax, running behind the trachea and the heart, and ultimately through the diaphragm and opens into the stomach.
4. Stomach: The stomach is a dilated T-shaped sac-like structure of the alimentary canal situated in the abdominal cavity. The stomach consists of three parts The cardiac part Is the junctional part of the stomach and the esophagus. Here the smooth, thick circular band, called the cardiac sphincter, is present, the Pyloric part The other end of the stomach is called the pyloric part. To this end, the stomach becomes continuous with the small intestine. At the pyloric end pyloric sphincter is present middle part is known as the Body.
5. Small Intestine: A small intestine is a coiled, narrow, muscular tube that is about 6 m long. It originates from the stomach and ends in the caecum. The first part of the small intestine is called the duodenum which is almost a ‘C’-shaped loop of about 20-25 cm long. Ducts of the pancreas and liver (gall bladder) open together into the duodenum to send their digestive juices. The second and last part of the small intestine are highly coiled tubes and are respectively known as jejunum (about 2-5 m long) and ileum (about 3-5 m long).
6. Large Intestine: The large intestine is much shorter (about 1.5 m long) and broader than the small intestine. The caecum is the wide sac-like structure of the large intestine situated just around and below the ileocolic junction. It is only about 6-5 cm long, continuous with the colon above and blind below. A blind finger-like tube, called a vermiform appendix, opens into the caecum. The colon is a longer tube which is about 1-4 m in length. It ascends first from the upper end of the caecum to the ventral surface of the liver at the right side of the abdomen. It is known as the ascending colon. The colon then proceeding transversely towards the left side up to the spleen is known as the transverse colon. At last, the colon runs down along the left side of the abdominal cavity and is known as the descending colon ultimately forming a downward and slightly curved loop of the pelvic colon (Sigmoid colon), which continues into the rectum. The latter is the dilated and short last part of the colon and opens to the exterior through theanus.

Function: The large intestine absorbs mainly water from the food remnants, stores the remnants and afterward forms a stool. It is eliminated to the exterior through the anus.

Accessory Organs: Certain glands such as salivary glands, liver, and pancreas form the accessory organs.

Salivary glands: Three pairs of salivary glands are present in the mouth cavity.

Parotid gland:  It is located at the corner of the mandible and ear lobe on each side of the face.

Submaxillary or Submandibular gland: It is surrounded by the mandible and  Sublingual gland It is situated below the tongue. Salivary ducts, carrying the saliva, open into the mouth near the molar teeth and also on the floor of the mouth.

Function: Salivary glands secrete saliva.

Parotid is the largest salivary gland but maximum saliva is secreted from the submaxillary or (submandibular gland).

Liver: The liver is the largest gland of the body. It is situated below the diaphragm and above and on the right side of the stomach. It is divided mainly into the right and left lobes. The gall bladder is an elongated, pear-shaped, muscular elastic sac about 7-8 cm long, lying under the lower surface of the liver. Bile secreted by the liver comes out through the hepatic and cystic ducts and remains stored in the gall bladder. From the gall bladder, bile passes through the common bile duct into the duodenum.

Function:

1. The liver secretes bile.
2. It acts as an important metabolic as well as an excretory organ of the body.

Pancreas: The pancreas is a mixed gland that is about 20 m long and 4cm broad situated beneath the stomach within the ‘c’-shaped space of the duodenum.

Functions:

1. It is composed of pancreatic alveoli or acini (exocrine part) which secretes pancreatic juice (digestive juice),
2. The a and (5 cells of islet of Langerhans tissue of the pancreas (endocrine part) secretes two hormones in the blood, glucagon and insulin respectively.

General Functions of Alimentary System: The main functions of the alimentary system are

1. Ingestion: Food is taken by the mouth cavity,
2. Digestion: complex food is converted to simple food by the process of digestion in the stomach and small intestine. Different digestive glands take part in this process,
3. Absorption: The digested simple food is absorbed by the villi of the small intestine of the alimentary canal,
4. Egestion: Temporarily stored undigested food in the rectum is eliminated as stool.

Different Parts Of the Digestive System And Their Role In Nutrition :

How can you explain that from the viewpoint of digestion, the pancreas is more important than the liver?

Overview of Digestion

The whole process of digestion is completed by two major events:

1. Mechanical (physical)events
2. Biochemical (Enzymatic)events.

1. Mechanical (Physical) Events during digestion:

• Chewing (Mastication): It is a physical process by which solid food breaks into small fragments by teeth. These smaller fragments of food mixed with saliva form bolus that are easily swallowed. The total surface area of fragmented food particles is increased so that digestive enzymes can act better.
• Swallowing (Deglutition): The physical process (movement) by which food bolus passes
  from the mouth cavity into the stomach through the esophagus is called swallowing or deglutition. It is a complex inborn reflex process.
• Peristalsis: It is the slow but lateral wavy movement of the alimentary canal consisting of waves of alternate contraction and relaxation by which food materials move downward in the alimentary canal. Peristalsis helps in digestion by proper mixing of food with digestive juice. It also helps in the absorption of digested food and the digestion of feces.

Peristalsis:

A slow but lateral progressive wave-like movement that occurs involuntarily in hollow tubes, like the esophagus of the alimentary canal. It consists of the contraction of muscles above the distention, with the relaxation of the region immediately below the distended region. This causes the contents of the tube to be forced down the tract. Movement of food in the form of bolus through the alimentary tract takes place by peristalsis. Can you explain why you feel abdominal pain if you run after a full lunch?

2. Biochemical (Enzymatic) events during digestion: Protein, fat, carbohydrates, and other macromolecules must be properly digested into soluble micromolecules so that they can be properly absorbed. During this digestion, there are profound chemical changes. Various digestive enzymes are responsible for biochemical reactions at different parts of the alimentary canal.

LHydrolysis: It means the breakdown of chemical bonds of macromolecules of food by the addition of water during enzymatic digestion.

Example: Sucrose(C₁₂H₂₂O₁₁)+H₂→Gluscose(C₆H₁₂O₆)+Fructose(C₆H₁₂O₆)

Now, do you understand why we should drink water after lunch or dinner?

Digestive Enzymes

Digestive Enzymes: Enzymes taking part in digestion are called digestive enzymes.

They are of three types

1. Proteolytic enzymes or Protein-hydrolysing enzymes: These enzymes hydrolyze proteins into polypeptides and amino acids, for Example.Pepsin, Trypsin, Chymotrypsin, Erepsin, Renin.
2. Lipolytic enzymes or Lipid hydrolyzing enzymes: These enzymes hydrolyze lipids (fats) into fatty acid and glycerol Example. Lipase (Gastric Lipase, Pancreatic Lipase, Intestinal lipase).
3. Amylolytic enzymes or Carbohydrate hydrolyzing enzymes: These enzymes hydrolyze the carbohydrate into monosaccharides (glucose), for example, Amylase, Sucrase, Lactase, Maltase, etc.

Bile does not contain any digestive enzyme but it breaks down bigger molecules o smaller droplets to increase the surface area for the action of lipase. This is called emu s of fat.

Digestive enzymes with examples and their role in digestion

 

Try To Reflect:

• The pancreas is a mixed gland having exocrine and endocrine parts. All pancreatic enzymes are secreted from the exocrine part of the pancreas called acini. (Endocrine part secrete hormones).

Do you know the name of the endocrine part of the pancreas?

• Salivary gland enzymes react in the neutral medium; Gastric enzymes react in an acidic medium; Intestinal enzymes react in an alkaline medium. HCL is secreted from the stomach. Hence medium of the stomach is acidic. The alkaline substance is secreted from bile and the pancreas—so the intestinal medium is alkaline.

Try to explain why the ‘rice feeding ceremony’ (Annaprasan) is held after 6 months of a baby.

Difference between Chyme and Chyle :

The action of different enzymes present in the digestive juices of the alimentary canal:

Overview of Absorption Assimilation and Egestion

1. Absorption: The process by which the water-soluble digested end products of carbohydrates, proteins, fats, and other ingested food are transported from the alimentary canal into the lymph or bloodstream is called absorption.

• Site of absorption: Absorption occurs chiefly through the small intestinal epithelial cells present on the surface of the villi.
• Process of absorption: After absorption through epithelial cells of villi, molecules like amino acid, monosaccharides, vitamins, minerals, and H₂O are transported by blood capillaries, whereas fatty acids, triglycerides, etc. are transported by lymph in lacteal vessels. The process of absorption may be active or passive. It may be also carrier-dependent or carrier-independent.

2. Assimilation: In this process, the absorbed food material is transformed into intracellular protoplasm as well as extracellular material.

• site of assimilation: This process occurs in all cells and tissues of the body.
• Process of assimilation: Suppose, you have eaten a certain amount of rice that contains starch. This starch is digested into glucose and is distributed all over the body by blood. In different cells of the body, the same glucose molecule may be utilized in different ways. For example, Glucose may be transformed into glycogen In the liver and muscle or may undergo glycolysis in neurons, WBC, or other cells, or may be converted to other biomolecules like amino acid, glycerol, or fatty acid in some other cells. This conversion is assimilation which depends on the needs of the cell.

3. Egestion: In this process, undigested food materials go out of the body as feces.

• Site of egestion: Colon, rectum, and anus.
• Process of egestion: As the rectum is gradually filled up with stool, there will be an autonomous reflex that results in the contraction of the rectal muscle. The anal aperture opens and the fecal matter is discharged outside the body. Can you write a few points of difference between excretion and egestion?

Metabolism

Metabolism Definition: Metabolism is the total of biochemical reactions in the living cell of an organism, which involves the synthesis of complex substances from simple ones with the utilization of energy and the breakdown of complex substances into simpler ones with the release of energy. Now try to compare digestion and metabolism.

Anabolism Definition: It is the constructive process by which complete molecules are formed into simpler units with the help of energy resulting in increases in the dry weight of the organism.

Examples: Formation of glycogen from glucose, formation of protein from amino acids, photosynthesis, etc.

Catabolism Definition: It is the destructive procedure by which complex molecules are broken into simpler units with the liberation of energy resulting in a decrease in the dry weight may the organism.

Example: By respiration, glucose is broken into CO₂ and H₂O with the release of energy.

Anabolism and catabolism are opposite processes of reversible chemical reactions which may be represented as follows:

Small Molecule → Large Molecules

Difference between Anabolism and Catabolism :

Significance Of Metabolism:

1. The functional activities of the body depend on various metabolic reactions continuously taking place within the cell of an organism.
2. Various anabolic reactions result in the formation of macromolecules like fat, glycogen, etc. that are stored in respective organs Example fat in adipose tissue, glycogen in the liver and muscle, etc.
3. Many enzymes participate in all metabolic reactions resulting in intramolecular or intermolecular transformation.

The growth of an organism occurs when anabolism exceeds catabolism.

Difference between Digestion and Nutrition :

In a tabular form, can you mention what are the metabolic end product and digested end product of protein, fat, and carbohydrate?

Digested end product and Metabolic end product:

Dietary Food Intake, Energy Requirement, And Associated Problems

Concept of a Balanced Diet:

Balanced diet Definition: A diet that contains carbohydrates, fats, proteins, vitamins, and mineral salts in correct proportion to meet the energy requirements of the working capability of an organism is known as a balanced diet.

• The concept of a balanced diet varies from one group of animals to others, For Example, (Milk contains almost all important constituents except iron and vitamin C).
• Milk serves as a balanced diet for children but not for adults. The general ratio of a balanced diet of carbohydrates, protein, and fat is 4:1:1.
• A balanced diet depends on age, sex, height, weight, type of work, climate, and some other conditions.

Basal metabolic rate (B. M. R.) :

• Direction: The rate of the amount of heat required for performing the vital activities by
  a subject who, though awake, is lying in a state of maximum physical and mental rest under comfortable conditions (of temperature, pressure, and humidity), 12-18 hours after meal is called basal metabolic rate.
• Normal BMR: It is usually expressed as large calories (Kcal) per square meter (m2) body surface per hour.
  • In adult male the BMR is40 Kcal/m2/hour
  • In adult females, the BMR is 37 Kcal / m2 / hour.

BMR can be measured by an instrument named the Benedict Roth apparatus.

Factors affecting B. M. R.: Age, sex, body surface area, climate, diet, habit, hormones, etc.

Significance: BMR signifies the metabolic rate and function of different vital organs of the body.

Calculation of energy required daily for an adult human :

Calorie (cal) is the unit of energy and is defined as the amount of heat energy that can raise the temperature of 1 gm of water from 15°C to 16°C. In the biological system calorie is used as Kilocalorie (Kcal).

For daily calorie requirements of an adult healthy man, weighing about 60 70 kg and doing moderate work is about 2500 3000 Kcal. This amount of energy is derived from energy-yielding food like carbohydrates, proteins, and fats. On complete oxidation (combustion) these types of food yield the following amount of energy :

1 gram of carbohydrate → yields 4-0 Kcal

1 gram of protein → yields  4-1 Kcal

1 gram of fat →yields 9-3 Kcal

Therefore, a man (60-70 kg body weight) doing moderate work requires about 3000 kilocalories. Thus to fulfill this calorie requirement he should consume the following amount of carbohydrates, proteins, and fats in a ratio of approximately 4:1:1. (Carbohydrate: Protein: Fat) along with vitamins, minerals, and water to satisfy his or her daily calorie (energy) requirements.

Carbohydrates 415 gram = 415 x 4-0 = 1660 Kcal

Proteins 100 gram = 100 x 4-1 = 410 Kcal

Fats 100 gram = 100 x 9-3 = 930 Kcal

Total energy yields = 3000 Kcal

Metabolism-related problems in the human body:  So many problems may develop in the body due to metabolic disorders. Some of the common examples are mentioned below:

Obesity: This is defined as a body weight 10 to 20 percent above a desirable standard as the result of an excessive accumulation of fat. Obesity is hazardous to health and may cause— heart disease (cardiovascular disease), high blood pressure (Hypertension), Lung disease (Pulmonary disease), Diabetes, Arthritis, etc.

Kwashiorkor: It is Protein Calorie Malnutrition (PCM) when someone takes sufficient food but not a balanced diet, taking 2nd class protein (incomplete proteins). It may cause swelling of the abdomen, enlarged liver, lethargy, dry skin, loss of hair, and r sometimes mental retardation.

Marasmus: This is also Protein- Calorie-malnutrition (PCM). Here someone does not get sufficient food (inadequate intake of both protein and nonprotein food). This may result
in retarded growth, being underweight, dry r skin, and hair, etc. Fig. io.io: A-Kwashiorkor, B-Marasmus.

Phenylketonuria (PKU): It is an inheritable genetic disorder that results in the metabolic error of the amino acid phenylalanine. This may cause mental retardation.

Cystic Fibrosis (CF): This is an inherited disease of metabolic disorder of exocrine glands that affects the pancreas, respiratory passage, salivary glands, and sweat glands.

Circulation

Circulation Introduction: There are several essential physiological functions of the body like growth, nutrition, respiration, excretion, etc.

• For all these functions, free movement of respiratory gases (O₂ and CO₂), enzymes, vitamins, hormones, nutrients, etc. is urgently needed.
• It is also very much essential to remove excretory toxic substances (like urea, uric acid, etc.) produced by metabolism. For all these, a suitable liquid medium is required.
• The major circulating medium in animals is blood and lymph. Movement of various substances dissolved in the liquid medium throughout the body is called circulation.

What is Circulation: The process by which various necessary substances like nutrients, respiratory gases (O₂ and CO₂) hormones, enzymes, minerals as well as excretory products, etc. are transported to respective organs of the body is called circulation.

Concept of Circulation

1. Importance (Functions) of Circulation :

Circulation of blood acts mainly as a transport medium and helps the living body to perform several important functions as stated below:

• Transportation of nutrients—The digested food substances are absorbed from the digestive canal and carried by blood plasma or lymph to all living body cells to provide nutrition.
• Transportation of respiratory gases—The oxygen (O₂) for respiration is carried from the lungs to the tissue cells and carbon dioxide (C02) produced in the tissue cells is carried by blood (RBC) to the respiratory organs from where it goes out.

CO + Hb → Carboxyhaemoglobin O₂ + Hb →Oxyhaemoglobin ;

CO₂ -t- Hb →Carbaminohaemoglobin.

• Transportation of enzymes and hormones—The enzymes, hormones, etc. are essential for the proper functioning of the living body. They are synthesized and liberated from several sources and are carried by blood (plasma) to the respective sites of action.
• Transportation of waste products—Various toxic metabolic waste products formed as a result of cellular metabolism are liberated from the body through circulation (plasma).
• Helps in storage—The essential substances or other organic matter formed in excess within the living body are carried by circulation (plasma) to the storage organs for future use.
• Maintenance of blood pressure—Blood circulation maintains blood pressure and thus regulates the exchange of fluids and ions between blood and tissues.
• Transportation of minerals—Various minerals are transported by circulation (plasma) from one part of the body to another. ‘
• Generation of heat—By circulation the cells receive food (respiratory substrate) and O₂ and then the cells produce heat energy by respiration.

2. Components of the circulatory system of humans: The blood-vascular system of man consists of blood, blood vessels, and the heart. The heart is the pumping organ. The contraction of the heart is systole and that of expansion is diastole. Due to this pumping action, a pressure gradient is generated by which blood flows all over the body through blood vessels—arteries, veins,s and capillaries.

Are you aware of the fact that a parallel fluid (besides blood) flows all over the body?

Difference between Artery and Vein :

Difference between Pulmonary artery and Pulmonary vein :

Types of Circulation (The basic idea of open and closed circulation

Two types of blood vascular systems are found in animals; such as—the open blood vascular system and the closed blood vascular system.

Open circulation in Cockroach Definition: The system in which blood from the heart passes through the blood vessels at first and then opens into the body cavity (hemocoel) is called open circulation.

The open circulatory system consists of the blood vessels (without capillaries) and the hemocoel or lacuna or sinus. In this type of circulation blood flows partly through the blood vessels and partly through the body cavity or hemocoel. As the blood flows out of the blood vessels into the lacunae or sinuses or hemocoel, it comes in direct contact with the tissue cells.

Examples: This type of circulation is found in many invertebrates like cockroaches, grasshoppers, prawns (Arthropoda) snails, union, etc. (Mollusca).

Closed circulation in Human Definition: The system in which the circulating blood always remains within the heart and blood vessels but never flows into the body cavity is called closed circulation.

The closed blood vascular system consists of blood vessels and the heart. In this type of  Open Circulation and Closed Circulation in man. circulation the blood is pumped out by the heart to arteries and then to capillaries present in the tissues. From the capillaries, blood returns to the heart again through the large veins. Thus blood never comes out of the blood vessels.

Examples: This type of circulation is found in invertebrates like earthworms and in all vertebrates like fish, Amphibia, Reptiles, Birds, and Mammals,

Difference between Closed and Open circulation :

Can you explain the advantages and disadvantages of open and closed circulation?

Different Body Fluids Their Location And Function (Role)

Blood Definition: It is the fluid connective tissue and is the most important transporting medium of the body. It consists of plasma and blood corpuscles.

Location: Blood is present in the blood vessels and heart of the body.

Role (Function): It carries various materials from one part of the body to the other. (Details of the composition and function of blood will be explained later)

Lymph Definition: The alkaline clear, pale yellow color watery modified tissue fluid found in the lymphatic vessels and lymph glands (nodes) is called lymph.

Location: Lymph is present in lymph vessels and lymph glands of the body. The total amount of lymph in man is about 1-2 litres.

It contains 94% water and 6% solid substances. Solid substances are both organic (proteins, carbohydrates, fat, non-protein nitrogenous substances) and some inorganic substances.

Role (Function) of lymph:

1. Acts as transport medium:  Lymph transports nutrients and oxygen and supplies them to the tissue cells where the blood cannot reach directly.
2. Transport of fatty materials: The lymph absorbs fat from the intestine.
3. Drainage of tissue fluid and metabolites: Lymph drains away excess tissue fluid and metabolites. In this way, it keeps the volume and composition of tissue fluid constant.
4. Defensive functions: The lymphocytes and monocytes present in the lymph protect the body with their phagocytic properties.

Difference between Blood and Lymph :

You will be surprised to know that there are approximately 6-10 liters of lymph in the body, compared to 3-5 – 5 liters of blood.

Sweat Definition: lt is the fluid secreted by the sweat glands in the skin of our body.

• Location: Sweat glands are present in the dermis of the skin of our body. Secretion of sweat depends on the weather, activity of the body, mental stress, etc. The average sweat rate in an adult is approximately 2-4 liters per day but less in children.
• Role (Function): Sweating has many functions in the body but primarily it is responsible for thermoregulation water in sweat absorbs latent heat of evaporation from the skin so the body cools down. What do you understand by ‘panting’ in a dog?

Urine Definition: It is a liquid by-product of the body secreted by the kidneys, temporarily stored in the urinary bladder, and is eliminated through the urethra outside the body.

• Location: Urine is filtered from blood in the nephron of the kidney, transported from the kidney by the ureter, and stored in the urinary bladder. Average urine production in adults is about 1-2 liters per day. However, urine volume depends on hydration, activity, environmental factors, etc.
• Role (Function): It is the primary process of elimination of toxic metabolic waste of the body.

Why is urine slightly yellowish?

CSF (Cerebro Spinal Fluid) Definition: It is a clear colorless body fluid found in the brain and spinal cord.

• Location: CSF is produced in the choroid plexus of the brain approximately 500 ml per day.
• Role (Function): CSF maintains buoyancy of being. ain, protection of the brain, transport of various substances between blood and brain, removal of metabolic waste, etc. CSF serves the function of lymph in the brain.

Synovial Fluid Definition: This is a viscous fluid found in the cavity of the synovial joint which is a movable joint of two or more bones.

• Location: The inner membrane of the synovial joint is called the synovial membrane which secretes synovial fluid into the joint cavity. There are two types of cells in the synovial membrane—type A and type B. Type A is derived from blood monocytes whereas type B produces synovial fluid. Many enzymes and acids are present in this fluid.
• Role (Function): The principal role of synovial fluid is to reduce friction (acts as a lubricant) between the articular cartilage of synovial joints during movement.

Tissue Fluid Definition: Tissue fluid (Interstitial Fluid) is a solution that is present in the intercellular space or tissue space in our body.

• Location: On average, a person has about 10 liters of tissue fluid which is filtered from blood plasma in the capillaries.
• Role (Function): Interstitial fluid flows over the cells and tissues. This provides a means of delivering materials to the cells, intercellular communication, as well as removal of metabolic waste.

Intracellular Fluid (ICF) Definition: The fluid that is present inside the plasma membrane of a cell is called intracellular fluid. It is also known as the cytosol or cytoplasmic matrix.

Cytosol = Cytoplasm—Cellular organelles

• Location: In the eukaryotic cell of the human body, the ICF is present within the cell and is part of the cytoplasm. The cytosol is a complex mixture of organic and inorganic substances. However, more than 70% of the cytosol is water but this percentage varies in different types of cells.
• Role (Function): ICF performs almost all intracellular metabolic activities and life processes like the flow of impulses through neurons, division of cells, protein synthesis (translation), glycolysis, glycogenesis, gluconeogenesis, and so on.

Composition Of Blood

Composition Of Blood Definition: Blood is an opaque, slightly alkaline, reddish-colored, salty taste, viscous specialized fluid connective tissue. The total volume of blood in an adult human is approximately 5 liters.

Color of the blood: The color of human blood is red. It is due to the presence of the respiratory pigment called hemoglobin.

Do you know plant sap is acidic but animal plasma is alkaline?

Why is blood called “specialized fluid connective tissue”?

1. Blood consists of different types of cells (RBC, WBC, etc.) so it is called ’tissue’.
2. Blood contains a huge matrix (plasma) and also it flows from one part of the body to another thus connecting different parts of the body it is called ‘connective tissue’.
3. As it flows to different parts of the body—so it is called ‘fluid’.
4. In the blood matrix (plasma), there is no connective tissue fiber (like collagen, etc.). So blood is fibreless. This is the specialty of blood. So it is called ‘specialized connective tissue’.

Composition of blood

For Reference Only:

Why blood cells are called corpuscles? Blood cells (especially RBC) are called corpuscles since they are not typical cells For Example RBC is a living cell but nonnucleated and cannot divide. WBC exhibits pseudopodial or amoeboid movement. Platelets are cell fragments, also nonnucleated.

1. Plasma-Definition, composition, and Functions Definition: Plasma is the pale yellow-colored fibreless intercellular alkaline fluid in which blood cells remain suspended.
   1. (Plasma = whole blood-cellular part of the blood)
2. Composition of plasma: The total amount of plasma is 55% of total blood or about 6% of total body weight. It consists of 91-92% water and 8-9% solid substances. The solids remain dissolved in the plasma and are mainly of two types:

Inorganic constituents—The main inorganic constituents are sodium, potassium, calcium, magnesium, phosphorus, chlorine, bicarbonate, iron, copper, etc.

• Organic constituents—The important organic constituents are carbohydrates and glucose.
• Protein—Albumin, globulin, prothrombin, and fibrinogen.  Fa Neutral fat, phospholipids, cholesterol, etc.  Non-protein nitrogenous substances (NPN)—Urea, uric acid, ammonia, creatine, creatinine, etc. Other organic substances— Enzymes, hormones, bilirubin, antibodies, waste products, etc.
• Gases— Oxygen and carbon dioxide (in dissolved state).

Functions of plasma :

1. It helps in blood clotting. The fibrinogen and prothrombin are two proteins which help in blood clotting.
2. The liquid part of the plasma helps in the transport of various substances like digested food, vitamins, minerals, respiratory gases (02 and C02), hormones, etc.
3. Plasma acts as a protein reservoir.
4. It acts as a buffer that maintains the acid-base balance of the blood.
5. It maintains the viscosity and colloidal osmotic pressure of blood. 6. Plasma helps to synthesize antibodies.
6. Circulating plasma helps to regulate body temperature (thermoregulation).
7. It takes part in the transport of O₂ (as a physical solution) and CO₂ (as a bicarbonate compound).
8. It transports metabolic wastes like urea, uric acid, etc. to form urine in the kidney.

Why do we feel drowsy after lunch or dinner?

Blood Corpuscles (Formed elements of blood):

For reference only:

Flow chart of different stages of development of RBC:

Haemoncytoblast → Proerythroblast→Erythoblast→Reticulocyte→Erythrocyte

Vit B₁₂ (cyanocobalamin) and Vit B9 (Folic acid) are responsible for the maturation of RBC.  Haemoglobin is synthesized in the proerythroblast (Pronormoblast) stage during the development of RBC.

For reference only:

What is the chemical nature of granules in granulocytes?

Granules in granulocytes are clusters of hydrolytic enzymes that help in destroying the phagocytosed substance.

For reference only :

Diapedesis: The passage of WBC by pseudopodial movement through the intact capillary wall into the surrounding tissue is called diapedesis.

• That’s why WBC (larger than RBC) may come out of blood into intercellular space but RBC (smaller than WBC) cannot come out.
• Platelet count drops in Dengue and cancer chemotherapy.
• Probably you know less number of RBCs than the normal value is called Anaemia. What is called when the count of RBC increases?
• Do you know the RBC of the camel is nucleated? Since matured human RBC is non-nucleated. how can you justify whether it is a living cell or a dead cell?

Types of WBC (White Blood Corpuscle):

According to the presence and absence of granules in the cytoplasm, the white blood corpuscles are of different types.

You will be surprised to know that immature lymphocytes are larger and matured lymphocytes are smaller in size.

Functions of different types of WBC:

Monocytes and neutrophils are together called phagocytes since they can perform phagocytosis.

Difference between RBC and WBC:

Respiratory pigments Description: Those pigments, present in the red blood cells or the plasma, that help in gaseous transport between respiratory organs and tissue cells called respiratory pigments.

Types: Two main types of respiratory pigments are found in the animals i.e., hemoglobin and hemocyanin.

Haemoglobin:

Description: Haemoglobin is an iron-containing red pigment of blood.

Composition (Chemistry): Haemoglobin is a protein (chromoprotein) and (metalloprotein) in nature. It consists of haem (4%) and globin (96%). Haem is an iron-containing part, whereas globin is a simple protein. Haemoglobin is called chromoprotein as it has a red color; it is called metalloprotein since it contains iron metal.

Location: Haemoglobin is found in the red blood cells of all vertebrates and the plasma of earthworms.

Normal amount: In normal conditions, 100 ml of human blood contains about 14-5 gm. of hemoglobin in adult males but in females slightly less (due to less number of RBC).

Functions of hemoglobin:

1. Hemoglobin helps to carry oxygen from the lungs to tissue as oxyhemoglobin in the blood. It helps to carry carbon dioxide from the tissue to the lungs as carbamino hemoglobin. O₂ is carried by the haem part and CO₂ is carried by the globin part.
2. Haemoglobin acts as a buffer which maintains the acid-base balance of the blood.
3. It forms different pigments, for example, bilirubin, biliverdin, etc. after a metabolic breakdown.

For reference only:

CO (Carbon monoxide) combines with hemoglobin to form carboxyhemoglobin. One rich source of CO is cigarette smoke.

Haemocyanin :

Description: Haemocyanin is a copper-containing pigment of blood.

Location: Haemocyanin is found in the plasma of prawns, crabs, and a few other invertebrates.

Chemistry: Haemocyanin is copper copper-containing pigment which is a protein in nature. In normal conditions, it remains colorless but turns a light bluish color when it comes in contact with oxygen (Oxyhaemocyanin).

Function: Haemocyanin helps to carry oxygen in blood.

Difference between Haemoglobin and Haemocyanin :

In earthworms, there is no RBC. Then where is hemoglobin present in blood?

Blood Group And Blood Donation

Blood Group :

Human Blood: Human blood can be divided into different groups according to agglu tinogen (antigen) and agglutinin (antibody)— known as blood groups.

ABO System: Human blood can be divided into four groups- A, B, AB, and 0 according to agglutinogen and agglutinin—known as ABO system.

Discovery: ABO system was discovered by Karl Landsteiner in 1900, for which he was awarded Nobel Prize later in 1930.

Agglutinogen: This is a type of antigen, present on the surface of RBC. It can be of two types—A and B. Chemically they are complex oligosaccharides.

Agglutinin: This is a type of antibody (gamma globulin—I_g), present in blood plasma. It can be of two types—a and p. Chemically they are protein in nature—mostly IgM and I_gG.immunoglobulin molecules.

Naming of blood group: The blood group is named according to the type of agglutinogen present in it e.g. if agglutinogen A is present on the surface of RBC, it is called A .group and so on.

Landsteiner’s rule: “If a person contains certain agglutinogen in blood he always lacks the corresponding agglutinin”, example Blood with A agglutinogen never contains corresponding a-agglutinin; similarly blood with B agglutinogen never contains P-agglutinin.

Details of the type of blood group:

Concept of “universal donor” and “universal recipient”:’ O’ group blood does not contain any antigen (A or B) so this group may be donated to any person in an emergency. so 0 group blood is called a “universal donor”. Conversely AB group * does not contain any antibody (a or P)-so this group may receive blood from any group under emergency. so the AB group is- called a “universal recipient”.

However, the same group of blood is advised best for transfusion.

Difference between Agglutinogen (Surface antigen) and Agglutinin (Blood group antibody):

Rhesus factor (Rh factor) and its Importance: Landsteiner and Wiener (1040) discovered a substance, a type of agglutinogen, from the blood of Rhesus monkeys.

For reference only:

Rhesus monkey is a small brown macaque with red skin on the face, found in southern Asia. In India, it is found in the Himalayas, forests of Assam, and Sundarban in West Bengal. It is extensively used in iGSGaich work.

• It is also present in human red blood corpuscles of about 85% of people. Since it was first discovered in Rhesus monkeys, this agglutinogen is known as the Rhesus factor or in short Rh-factor.
• There is no corresponding agglutinin in the human plasma. Those persons who possess the Rh factor are known as Rh-positive (Rh ‘) and those who do not possess the Rh factor are known as Rh negative (Rh-).
• Complications arise when Rh+ blood mixes with Rh“ mother’s blood. In this case, the baby turns weak, anemic, and jaundiced, or in severe cases detail of the fetus occurs. This is. called Erythroblastosis foetalis.
• There are six common types of Rh antigens, each of which is called Rh factor. They are C, D, E, c, d, and e of which type D antigen is widely prevalent in your blood test report if it is written that your blood is B+ or A, then what does it mean?

For reference only: The blood group of any person is determined by genes.

Significance Of Blood Grouping :

1. For blood transfusion, identification of blood groups is primarily needed.
2. The blood group of a person is a very important identity of the person.

• Have you seen that the blood group is mentioned on the ID cards of different persons?
• Blood transfusion, ABO incompatibility, cross-matching, and Haemolysis :

Blood transfusion: The transfer of blood from one person to another is called transfusion. People who give their blood for transfusion are called donors and those who receive blood transfusion are called recipients.

• While testing compatibility, the agglutinogen (Antigen) of the donor’s corpuscles and the type of agglutinin (Antibody) of the recipient plasma (serum) should be taken into account.
• Because the agglutinogen of the donor will react with the agglutinin of the recipient.

Examples:

• • A-agglutinogen will react with a-agglutinin (anti-A) and B-agglutinogen will react with (3-agglutinin (anti-B).
  • Thus antigens of donor’s blood should be compatible with the recipient’s antibodies. Otherwise clumping (agglutination) and then hemolysis breakdown of RBC occurs.

1. Agglutination: If there is a wrong incompatible blood transfusion, then corresponding agglutinogen and agglutinin may combine resulting in clumping of RBC called agglutination. In cross-matching of two blood groups, agglutination occurs when the donor’s RBC and the recipient’s plasma are incubated together—which indicates that the donor’s and recipient’s blood are incompatible.
2. Cross-matching: It is the process where the donor’s red blood corpuscles are mixed with the recipient’s plasma on a slide and checked for agglutination before the actual transfusion of blood. This is a mandatory medical rule.

For reference only:

Bombay blood group: The Bombay blood group is the rarest. It was first discovered in Bombay (Mumbai), India in 1952. It is also known as the h/h blood group or Oh blood group. It is found in 1 out of every 2,50,000 persons. They can donate blood to any member of the ABO blood group but can not receive blood from any member of the ABO system (since they always contain either antigen A or B or H). (H antigen is present in the O group).

Blood Donation Definition: It is a voluntary process when someone (donor) agrees to have blood drawn from his body to give it to someone (recipient) who needs a blood transfusion. Millions of people need blood transfusions each year. Some may need blood during surgery after an accident or in any other disease.

Types of blood donation :

1. Whole blood: This is the most common type of blood donation where the whole blood is donated.
2. Platelets: This type of donation uses a process called apheresis where only platelets and some plasma are collected from the donor.
3. Plasma: During apheresis, only plasma may be also collected.
4. Double red cells: in this process, only RBCs are collected by apheresis.

Blood Bank: This is a place where blood is collected from donors, typed (A or B or AB or O), separated into components, stored, and prepared for transfusion recipients. Generally, Na-citrate is used as an anticoagulant in the blood bank for the storage of blood.

The volume of blood donation: In India, a donor would donate only 250-300 ml of blood in one donation.

Do you know that US people may donate 450 – 500 ml / per donation and that Chinese only 200 ml/per donation?

Recovery And Time Between Donations:  Donors are usually kept at the donation site for 10-15 minutes after donating blood. Light refreshments or lunch is provided to the donor. The prick site of the needle is covered with a bandage.

Do you know, that during blood transfusion, a male donor’s blood can be donated to a female and vice versa (no gender specification)? Blood donation can be done after 18 years. of age with a body weight of 55 kg+.

Coagulation Of Blood

Coagulation of blood Definition: The process by which blood oozing out from the ruptured blood vessels loses Its fluidity in a few minutes and sets into a semi-solid jelly-like mass, is called coagulation.

Factors Involved in Blood Coagulation: Blood coagulation is a complex process that requires about 13 factors. All these factors are present in plasma except factor-ill (thromboplastin). Except for factor IV (calcium ion), all other factors are protein in nature. Some important factors are Factor I (fibrinogen), Factor II (prothrombin), Factor III (thromboplastin), Factor IV (CaH), and so on.

Coagulation of blood depends on the type of injury. Minor injury causes quick blood clots.

Process of blood coagulation: It takes place in three steps

When blood comes out of an injured area, the platelets come in contact with ruptured blood vessels (rough surface). The platelets are broken in the presence of several clotting factors of blood and produce intrinsic thromboplastin.

1. Thromboplastin is also produced from the damaged tissue cells (extrinsic thromboplastin or tissue thromboplastin) in the presence of Ca++ and other factors.
2. The prothrombin of plasma is converted to thrombin in the presence of Ca++ and thromboplastin.
3. Thrombin reacts with soluble fibrinogen to convert it into insoluble fibrin. In the meshwork of fibrin fibers, the blood corpuscles are entangled forming a plug which is called a clot.

Summary: Fountain reaction/Cascade reaction)

Normally in circulating blood: Uninjured Platelets + Prothrombin + Fibrinogen → no clot

After shedding of blood (after an injury):

Do you know about heparin that prevents intravascular clotting of blood when blood flows through blood vessels? Try to identify some other anticoagulants that are used in the biochemical laboratory. Have you heard the name of the “Royal diseaseHaemophilia” that was first discovered in the family of Queen Victoria? Do you know what happens in Haemophilia?

Significance Of Blood Coagulation :

1. It helps to stop hemorrhage.
2. It blocks the entry of germs through the wounds.
3. It also helps in maintaining normal blood volume.

Can you explain why flowing blood does not clot inside blood vessels?

serum: It is a light straw-colored fluid that comes out (exudes) of the fibrin network after blood clotting. It contains all the components of plasma except clotting proteins (Prothrombin and fibrinogen).

Internal Structure Of the Human Heart

Anatomical Structure: The heart is a conical muscular involuntary hollow organ of about 12cm long and 9 cm board, 250-350 gm in weight. it is situated in the throat behind the sternum and between the lungs. Its walls are made up of cardiac muscle (striated involuntary) fibers. The whole heart is covered by a double-layered membranous sac, called pericardium. It contains a small amount of serous fluid in the closed space between the two layers called pericardial fluid that acts as a shock absorber. The wall of the heart consists of the outer epicardium, middle thick myocardium, and inner thin endocardium.

Do you know the importance of pericardial fluid?

Do you know the name of the inner layer and outer layer of the pericardium?

Internal structure of Heart: The Human (mammalian) heart consists of four chambers, viz, two atria (auricle) and two ventricles; The chambers on the right side of the heart are completely separated from those on the left side by a muscular partition called septum.

The part of this septum separating the two atria is called the interatrial septum while the other part separating the two ventricles is called the interventricular septum. The two atria are separated from two ventricles by a partition called atrioventricular septum.

• The right atrium receives two great veins, the superior vena cava, and the inferior vena cava, which bring less oxygenated blood (venous blood) from all parts except the lungs. The left atrium receives oxygenated blood (arterial blood) from the four great veins called pulmonary veins, each from the two lungs.
• Blood is collected in the atria and enters into the ventricles through the apertures called atrioventricular apertures (openings). They are provided with valves that prevent the backflow of blood from the ventricle to the atrium.
• The valves at the right atrioventricular aperture are made of three cusps or folds and are called the tricuspid valves or right atrioventricular valves. At the left atrioventricular aperture, the valve is made up of two flaps or cusps and is called the bicuspid valve mitral valve, or left atrioventricular valve.
• The valves contain chordae tendinae which are attached to the papillary muscle. There are small muscular

projections, called papillary muscles present in the inner wall of the ventricles that are responsible for the attachment of valves to the wall of the ventricle. However, the wall of the ventricle is much thicker (3 times) than the auricle due to the specialized ventricular muscle called Columnqe carnage.

• From the upper parts of the ventricles arise the great arteries viz., the pulmonary trunk of the pulmonary artery from the right ventricle and the aorta from the left ventricle; The opening of these great arteries are also guarded by the valves which are called semilunar valve.
• The pulmonary semilunar valve allows the flow of blood from the right ventricle to the pulmonary artery but prevents backflow whereas the aortic semilunar valve allows the flow of blood from the left ventricle to * the aorta but prevents backflow.
• The valves of heart allow unidirectional flow of blood only’—Justify the statement.

Have you heard of the modern methods of heart surgery like Open heart surgery, Bypass surgery, etc.?

You should know how many chambers are present in the heart of different vertebrates viz. in fish hearts (2 chambers), in amphibia (3 chambers), in reptilia (3 chambers), and in birds and mammals (4 chambers).

Try to construct an evolutionary tree of the heart of vertebrate series. Note down your N observation.

Heart of crocodile: Though it is a reptile, it has a 4-chambered heart but there is a special opening known as Foramen of Panizza.

Junctional Tissues Of Heart:

These are specialized cardiac tissues that are responsible for the origin of cardiac impulses and their conduction all over the heart,

Types :

• SA Node (Sino Atrial Node) SAN: It is located in the right atrium and is known as the natural pacemaker of the heart since the conduction wave starts from here.
• AV Node (Auriculo Ventricular Node) AVN: It is situated in the right atrium and is known as the reserve pacemaker of the heart.
• Internodal fibers and Buchman’s bundle: It is situated in the right atrium.
• Bundle of His: It originates from the AV node and passes down as right and left branches on both sides of the interventricular septum.
• Purkinje fiber: It originates from the Bundle of His and is situated on the wall of both ventricles.

Pathway of conduction of cardiac impulse :

A Course of Circulation of blood through the heart

Circulation of blood in man was first demonstrated by William I. Larvey (1628).

• The heart is a living pump made up of involuntary muscle. Circulation of blood through the heart is unidirectional due to the presence of valves in the several openings (orifices) of the heart.
• Due to continuous contraction (systole) and relaxation (diastole) of the heart, the blood circulates within it as well as throughout the body within the blood vessels.
• Let us discuss the circulation of blood through the human heart.

1. At first, the venous blood (O₂ less and more CO₂– containing blood) from the upper and lower parts of the body comes through the superior vena cava and inferior vena cava respectively into the right atrium.
2. From the right atrium, the venous blood passes into the right ventricle by opening the tricuspid valves.
3. Thereafter contraction of the right ventricle expels the blood by opening the semilunar valves into the lungs through the pulmonary artery for oxygenation.
4. In the lungs, the venous blood (less oxygenated blood) is converted into arterial blood (more oxygenated blood) after taking oxygen from the alveoli of the lungs, and CO₂ enters the alveoli.
5. This arterial blood returns from the lungs through the four pulmonary Veins into the left atrium.
6. From the left atrium the oxygenated (arterial) blood passes into the left ventricle by opening the bicuspid or mitral valves present at the left atrioventricular opening.
7. At last during ventricular contraction, the arterial blood from the left ventricle passes into the aorta by opening the aortic valves (semilunar valves) present at the base of the aorta.

Do you know that ECG is done to check the normal functions of the heart?

A circular path of Blood Circulation within the heart and body:

Double circulation :

It is the process where oxygenated and deoxygenated blood flows through the heart separately but simultaneously in two different directions. Hence this type of circulation is called double circulation.

• Within the human heart, oxygenated and deoxygenated blood never get mixed. So they are separate.
• Pulmonary circulation consists of the right ventricle, pulmonary artery, lungs, pulmonary veins, and left atrium. Since blood travels a short distance between the heart to the lung and back to the heart this is called short circulation or short circuit circulation.
• On the other hand, systemic circulation consists of the left ventricle, left aorta, all over the body, superior vena cava, inferior vena cava, and right atrium. Since blood travels a long distance from the heart to all over the body and back to the heart it is called Long circulation Long circuit circulation or bigger circulation.

Do you know in the heart of fish there is only a single* circulation why? Explain why the heart “of a fish is called a venous heart.

The heart of a fish is two-chambered and always contains deoxygenated blood so it is called a venous heart.

For reference only:

The function of Eosinophil:

1. Granules in eosinophils contain different enzymes that help in defense of the body against diseases. Granules are modified lysosomes.
2. Eosinophil plays a crucial role in killing parasites, by its enzyme Cathepsin (a proteolytic enzyme).
3. Eosinophil secretes different enzymes like eosinophil peroxidase, ribonuclease (RNase), deoxyribonuclease (DNase), lipase, etc. that are toxic to parasite and host tissues.
4. Eosinophil degrades histamine (released by mast cell and basophil) by histaminase and thus helps to reduce inflammation.

The function of Basophil:

1. It secretes anticoagulant Heparin, (which prevents quick clotting of blood).
2. It also secretes Vasodilator histamine, (which promotes blood flow to the tissues).
3. Like eosinophils, basophils play a role in both parasitic infections and allergies.

Mast Cell:

It is a type of WBC. This is very much similar in both structure and function to basophil. Both are granulated cells that contain histamine and heparin. Basophils are present in blood whereas mast cells are located in connective tissue, skin, lining of the stomach, intestine, etc. They play an important role in defending these tissues from disease.

Concept Of Excretion

As a result of metabolism certain non-essential toxic chemical substances are formed 1 within the body. If these substances are allowed to accumulate, toxicity develops and the cell eventually dies. The metabolism of proteins in animal tissues produces most of the nitrogenous toxic substances.

• The rate of metabolism is directly proportional to the rate of excretion. In animals, more activity of the body causes more metabolism and so more excretion.
• The process by which the excretory materials are eliminated regularly from the body is known as excretion.
• The non-essential toxic substances that are produced during cellular metabolism are collectively called excretory products.
• The organs which are involved in the processes of excretion are called excretory organs. Therefore metabolic wastes from the body are eliminated by the process of excretion.

Excretion Definition: The process of elimination of non-essential toxic substances produced during cellular metabolism, continuously with the help of the excretory organs (in the case of animals) or by other means (in the case of plants) is called excretion. Excretion is a catabolic process, during which harmful substances are produced which are transported in the different parts of the body and afterward eliminated from the human body.

Importance or Significance of Excretion :

• Maintenance of normal health: The excretory products are harmful to the body. Excess amount of excretory substances when accumulated in the body causes toxic effects or even may cause death to the organism. Thus regular excretion of these excretory products prevents toxic effects and keeps the body fit.
• Maintenance of protoplasmic substances: Excretion has some role in maintaining the balance of different protoplasmic substances in the cell, the protoplasm in turn helps to
  keep normal life processes of the organism.
• Maintenance of osmosis: Excretion has some role in the regulation of osmosis.
• Role in the ecosystem: The excretory products are formed by the breakdown of nutrients.
• Economic importance: The economic importance of excretory products of the plants is vast for human as well as animal kingdom.
• Maintenance of water balance: In various organisms mainly in animals and from the human body excess amount of body water is excreted (eliminated) to maintain the water balance osmoregulation by this process.

Know the facts

Excretion is a catabolic process

It is due to the following reasons

1. The formation of excretory products occurs by a catabolic process.
2. Elimination of metabolic waste products from the body takes place.
3. This results in a decrease in the dry weight of the organism.

Process of Excretion in Plants

In plants, there are no special excretory organs for performing excretion. The metabolic waste products are stored in roots, stems, leaves, flowers, fruits, and seeds.

• Excretory materials are less formed in plants due to the low rate of metabolism in them than in animals.
• They do not cause any harm if stored in the plant body. Hence there is no necessity for an excretory system in a plant.
• Whenever required plants get rid of their excretory products through certain processes.

Reasons that cause lesser formation of excretory materials in plants?

1. Ammonia produced due. to metabolism is utilized in the formation of various nitrogenous compounds by plants.
2. Carbon dioxide and water obtained due to respiration are used during photosynthesis. The oxygen obtained from photosynthesis is used in the respiration.
3. In plants the metabolic process is dependent on carbohydrates, thus less nitrogenous materials are formed.
4. In the plant body, the excretory materials that do not contain nitrogen are often stored within certain organs, as they are not toxic.
5. In the plant body, the protein and nitrogenous compounds are broken down to ammonia which act as a useful substance.

From all these above reasons we can find that plant excretory products are less harmful than animal excretory products.

Features Of Excretion And The Processes Involved In The Removal Of Excretory Products In Plants

Some of the excretory products are stored within some specific cells of the plant body permanently. But most of them. the excretory products are stored in the cell at first temporarily and then liberated from the plant body by the following process:

• Shedding of barks: In mature tall trees, some excretory products are temporarily stored in bark (the superficial dead tissue layer of the trunk and branches of the tree). The stored excretory products are eliminated at regular intervals through the removal of bark. Examples Guava (Psidium), Arjun, Eucalyptus, etc.
• Shedding of leaves (leaf fall): In evergreen or deciduous plants, the excretory products are transported to the leaf cells where they are stored temporarily (before fall). These products are then eliminated with the abscision (fall) of the leaves. Examples- Silk Cotton, Bombax, Sirish, Albizzia, etc.
• Shedding Of Fruits: Mature fruits like apples, tamarind, and lemon, store some metabolic products sue as malic acid, tartaric acid, and citric acid respectively. These substances are eliminated through the falling of fruits.

Naming Of The Excretory Products In Plants And Animals

Excretory products are of two types, such as Nitrogenous excretory products and non-nitrogenous excretory products.

Nonnitrogenous excretory products :

• In plants: The products are resin, tannin, latex, gums, mineral crystals, organic acids, non-nitrogenous waste, essential oils, etc.
• In animals:  the non-nitrogenous waste products are carbon dioxide, bilirubin, lactic acid, carbonic acid, etc.

Nitrogenous waste products :

• In plants: The nitrogenous waste products are alkaloids, such as quinine, nicotine, morphine, atropine, reserpine, strychnine, daturine, caffeine, then, etc.
• In animals: The nitrogenous waste products are urea, uric acid, creatine, creatinine, etc.

Storage of excretory products

In animals: Animal excretory products are temporarily stored in the urinary bladder as urine and then excreted.

In plants: Plant excretory products are stored within the cells of different plant organs as they have no excretory organs to liberate those non-useful products.

Know the facts

Why is stool, not an excretory substance?

The stool is not produced out of metabolism, hence it is not counted as an excretory substance.

Nitrogenous Excretory products: Alkaloid

1. Nitrogenous excretory products of plants produced by protein metabolism,
2. Most of them are weak bases,
3. Many of them are poorly soluble in water but readily soluble in organic solvents,
4. Generally, bitter.

Origin And Economical Importance / Medicinal Value Of Some Alkaloids :

Non-nitrogenous Excretory products :

Composition, Characteristics and Examples, and Uses of Excretory Materials:

1. All excretory products are waste products but all waste products are not excretory products
2. All excretory products are waste products because they are toxic to the body, hence eliminated from the body example, urea, uric acid, etc.
3. Some waste products are eliminated from the body but they are not excretory products as they are not formed by the metabolic process, for example, stool. A stool is an undigested waste product.
4. Carbon-containing excretory products tannin of plants and CO₂ of animals

Process of Excretion in Animals

Various metabolic waste products are formed due to metabolic activities within the body of animals. These metabolic end products are called excretory products. Since there are more metabolic activities in the animal body, there will be more excretory products. The most important excretory products are nitrogenous Waste products e.g. urea, uric acid, ammonia, etc. These are very toxic to the organism—so must be eliminated from the body from time to time.

For reference only:

• Ureotelic, Uricotelic and Ammonotelic animals:
• The animal that mainly excretes urea as a major excretory product is called a ureotelic animal e.g. some fishes, most amphibians, and almost all mammals.
• The animal that mainly excretes uric acid as a major excretory product is called a uricotelic animal e.g. insects, reptiles (snakes, lizards), and birds.
• The animal that eliminates nitrogenous waste as soluble ammonia in water is called an ammonotelic animal e.g. most invertebrates, most fishes, tadpole larvae, etc.

Excretory Organs In Animals

Names Of Some Animals And Their Excretory Organ

Different animals have a characteristic excretory organ that has various shapes, sizes, and structures but perform the same function of excretion as well as water balance of the body called osmoregulation some common examples of animal excretory organs are as follows:

Contractile vacuole: It is a subcellular membranous organelle, mainly found in protists (for example. Amoeba, Paramoecium) and unicellular algae (for example Chlamydomonas), which primarily helps in osmoregulation. Excess water is collected in the contractile vacuole and so the vacuole swells. Then the vacuole comes in contact with the cell membrane, contracts, and releases excess water from the cell.

Flame cell: It is a specialized excretory cell found mainly in Platyhelminthes or flatworms (for example Taenia solium or Tape-worm), that removes an excretory product from the body.

• A bunch of flame cells are together called protonephridia.
• The flame cell is a nucleated ‘cup-shaped cell body with a bunch of flagella inside that looks like a flame of fire. Many flame cells are attached to a common excretory canal.
• Collected excretory. product from the cells is released in the excretory canal and then goes outside.

Nephridia: This is the excretory as well as osmoregulatory organ found mainly in Annelida like earthworms, leeches, etc. There are two basic types of nephridia metanephridia (larger) and protonephridia (smaller). In earthworms, metanephridia is found.

• It consists of a ciliated funnel called a nephrostome that collects excretory products from the coelom.
• The product flows through nephridia! tubule and finally goes out through the nephridiopore.
• In the tubule, however, various necessary substances are reabsorbed.

Do you find any structural and functional similarity between nephron and nephridia?

Malpighian tubule: This is a tubular excretory as well as osmoregulatory organ found in different Arthropoda (primarily in insects like cockroaches and others).

• These are a bunch of slender tubules, located at the junction of the midgut and hindgut. Most tubules are highly convoluted. The number of tubules varies.
• These tubules collect the excretory product from hemolymph and drain it into the hindgut, from where the product moves through the hindgut into the rectum and finally goes out through the anus.

Kidney: This is the most important excretory organ in higher animals. All vertebrates have kidneys. Like human kidneys, they are made up of many nephrons (the structural and functional unit of the kidney). The kidney is mainly responsible for the elimination of toxic metabolic waste products as well as osmoregulation, mineral balance, and so on.

Do you know that based on complexity, a kidney may be pronephros, mesonephros, and metanephros in vertebrates?

For reference only: Pronephros, Mesonephors, and Metanephros kidney :

1. Pronephros: It is the definitive excretory organ of primitive fishes. This is found in the embryo of higher vertebrates as a vestigial structure. It consists of several coiled tubules. It is present in Lamprey.
2. Mesonephros: It is one of the three excretory organs that develop in vertebrates. It serves as the main excretory organ of aquatic vertebrates (fishes). It is present in the kidneys of fish and amphibians.
3. Metanephros: The final excretory organ that develops in a vertebrate embryo is called metanephros kidney. In reptiles, birds, and mammals, metanephros • replaces mesonephros (during embryonic development) as the functional excretory organ and develops into an adult kidney.

During the embryonic development of kidneys in higher vertebrates, first pronephros develops which is replaced by mesonephros, and finally, metanephros kidney develops, which persists in adults of reptiles, birds, and mammals (including man).

Excretory System Of Human

Structure And Functions Of Excretory System Definition: The various organs that help to eliminate the toxic nitrogenous and non-nitrogenous waste products from the body (urine, sweat, etc.) form the system known as the excretory system. The important excretory organs of the excretory system are the kidney, liver, lungs, skin, etc.

Structure: The most important excretory system is the urinary system. As this system eliminates about 70 percent of excretory materials from the body—hence kidneys are known as the primary excretory organ.

Kidney: Two kidneys, which belong to the urinary system, are situated on the posterior portion of the abdominal cavity on either side of the vertebral column.

External structure: Each kidney is bean-shaped, dark brownish-red in color, and measures about 11 cm in length, 6 cm in breadth, and 3 cm in thickness. In adults, its weight is about 125—170 gm (average 150 gm). The lateral margin is convex, while the medial margin has a concavity in the middle and is called hilum. The renal artery and the renal vein enter the kidney, whereas the ureter leaves the kidney through this middle portion of the concavity.

Internal structure: If a kidney is cut through the middle in two longitudinal halves, then two regions are revealed to the naked eye an outer cortex and an inner medulla. The medulla is formed by a number (7-18) of striated conical structures called the renal pyramids. Each kidney is made up of about one million (10 lacs) of excretory units called the nephrons.

Kidney Functions:

1. Kidneys eliminate toxic and metabolic waste products from the body.
2. It maintains the water balance and salt balance of the body.
3. It maintains the acid-base balance of the body.
4. It manufactures certain substances like renin, ammonia, hippuric acid, and inorganic phosphate.
5. It synthesizes erythropoietin (a local hormone) which stimulates R. B. C. formation in the bone marrow.
6. It regulates blood pressure and osmotic pressure in the blood and tissues.

• Ureter: The ureters are two tubular structures. Each ureter arises from the hilum of each kidney. The ureter is about 25-30 cm long which expands at its upper end to form the broad pelvis.

Function: Urine formed in the nephrons of the kidney is carried along the ureter to the urinary bladder.

• Urinary bladder: The urinary bladder is a pear-shaped muscular bag-like structure. It is situated in the pelvic cavity in front of the rectum in males and in front of the uterus in females. It receives two ureters which run obliquely through the bladder wall in the posterior part of the urinary bladder and opens into it.

Function: It stores urine temporarily.

• Urethra: The urethra is a narrow canal that arises from the narrow neck of the bladder.
  It opens to the exterior, running through the penis in the male, but separately from the vagina in the female. Its length varies from about 18 cm in men to about 4 cm in women. A thick band of smooth muscle fibers called the internal urethral sphincter, and external sphincters are present. These two sphincters control the excretion of urine through the urethra.

Function: The single urethra carries urine from the urinary bladder outside the body. Urine is formed in the kidney, passes through the ureters, and is stored temporarily in the urinary bladder. This collected urine is voided by the act of micturition (urination) when the bladder muscles contract and the urethral sphincters relax.

Do you find any difference between the ureter and urethra?

Functions of the excretory system:

• Removal of waste products: All the metabolic products that are produced in the body are excreted mainly through urine and a small amount through sweat, sebum, etc. The products are—urea, uric acid, creatinine, ammonia, etc.
  • Do you know which artery and vein are carrying blood to and from the kidney?
• Maintenance of water balance: The excretory system regulates the elimination of water from the body and thus maintains water balance in the body. In summer, since there is more sweating, there is less urine formation, which is reversed in winter.

Have you heard about ‘Kidney stones’?

Out of two kidneys, a donor can donate one kidney which is transplanted into the body of the recipient. This is called kidney transplantation have you heard of it?

Nephron

Nephron Definition: The structural and functional unit of the kidney is called the nephron.

Structure: A single nephron is a coiled tubular structure with a dilated blind end. It is about 5 cm long and 0-6 mm in diameter. It consists of mainly two parts e.g., Malpighian corpuscle and Renal tubule.

Different parts of Nephron :

Structure: This is a double-walled cup-like structure situated in the cortex of the kidney. It is 0-2 mm in diameter and consists of two parts the Bowman’s capsule and the glomerulus.

• Bowman’s capsule-It is the double-walled dilated blind end of the nephron. The walls of the capsule are lined by a single layer of flat epithelial cells. The outer layer of Bowman’s capsule is called the parietal layer and the inner layer is called the visceral layer.
• Glomerulus- It is the tuft of loop-like capillaries (approximately 50 loops) invaginated within the double-walled Bowman’s capsule.
  1. The tuft of capillaries is formed by the division of short and wide afferent arteriole (approx 50x in diameter), a branch of the renal artery.
  2. The capillaries of the glomerulus reunite and form a long and narrow efferent arteriole (approx 25 in diameter).
  3. After leaving the glomerulus the efferent arteriole forms a second set of capillaries called the peritubular capillaries.
  4. These capillaries surround different parts of the renal tubule.

The function of the Malpighian corpuscle: It forms the filtering bed through which all the constituents of plasma except colloids of plasma (i.e., proteins, fats, etc.) are filtered and thus helps in urine formation. This type of filtration is known as ultra-filtration.

How can you compare the malpighian tubule and the malpighian corpuscle?

Renal tubule:

Structure: It is the tubular portion of the nephron. It is about 3 cm long and 0-02—0-06 mm wide originates from the lower portion of the Bowman’s capsule and consists of three parts.

• The first part of the tubule: It is the descending tubule which is highly coiled, approximately 14 mm long, and situated in the cortical region of the kidney. This part of the tubule is called the proximal convoluted tubule (PCT). The inner wall is lined by cubical epithelium.

Function: Almost all essential nutrients, 70-80% ions and electrolytes, and a huge amount of water are reabsorbed by PCT.

• The second part of the tubule -It is a U-shaped (hairpin-like) middle portion, a narrow tubular part approximately 8 mm long which is situated in the medullary region of the kidney and is known as Henle’s loop. The inner wall is lined by flat squamous epithelium.

Function: The descending limb of Henle’s loop is permeable to water whereas ascending limb is permeable to electrolytes. Thus water and electrolytes are reabsorbed here.

• The third part of the renal tubule -It is the ascending tubule approximately 6 mm long which is situated mainly in the cortical part of the kidney. It is comparatively wide and less coiled than the proximal convoluted tubule. This part of the tubule is called the distal convoluted tubule (DCT). The inner wall is lined by cubical epithelium.

Function: DCT helps in the reabsorption of Na+, H₂O₂, and HCO→ and maintains Na+- K+ balance in the blood.

Do you know PCT, Henle’s Loop and DCT together called Uriniferous tubule?

Why is the nephron so much convoluted?

1. In a small kidney, approximately 1 million- nephrons are present. So space is scarce hence the nephron is convoluted,
2. Due to convoluted nephrons, the speed of flow of urine is slow so that various essential substances can be easily absorbed,
3. In the convoluted nephron, the absorptive surface area is greater which is useful for reabsorption.

The distal convoluted tubules of different nephrons open in a wide straight tubule which is known asthecollectingtubule. It passes to the medulla and opens at the apices of the pyramids into the pelvis of the kidney.

The general function of the renal tubule :

• Reabsorption: As the capsular filtrate passes through the renal tubule, almost all the essential substances of the filtrate are selectively reabsorbed
• Secretion: Some substances are not present in the capsular filtrate but are found in the urine. This shows that the renal tubular cells secrete some substances like penicillin, phenol red, creatinine, etc. which come out through urine.
• Formation of new substances: The epithelial cells of the. tubule can manufacture some substances, like ammonia, inorganic phosphate, and hippuric acid, which are also excreted through the urine.

Role of the nephron in the formation of urine:

Urine formation involves three main steps glomerular filtration, tubular reabsorption, and tubular secretion. These steps take place in different parts of the nephron.

Step 1: Glomerular filtration or Ultrafiltration or Pressure filtration: The diameter of the afferent arteriole is approximately 50p and that of the efferent is 25p.

• Hence more blood comes in the glomerulus and less blood goes out of the glomerulus.
• Thus always certain amount of blood remains stored in the glomerulus which creates a pressure that causes filtration of various materials from blood.
• This process of filtration is called ultrafiltration where crystalloids are separated from colloids.
• The amount of filtrate formed by the two kidneys per minute is called. Glomerula Filtration Rate (GFR).
• In a normal healthy person, GFR is approximately 125 ml/minute i.e. 180 litres/day. GFR is controlled by the Juxtaglomerular apparatus (JGA).

Step 2: Tubular reabsorption: Out of 180 liters of glomerular filtrate per day nearly 178-5 liters are absorbed in the tubular part of the nephron (PCT, Henle’s Loop, and DCT)—which means almost 99% of the filtrate is reabsorbed.

• This is known as tubular reabsorption. This absorption in the tubular cells is either an active or passive process.
• All necessary substances like water, glucose, amino acids, Na+, etc. are almost completely (99%) reabsorbed.
• The process of tubular reabsorption is influenced by many hormones like vasopressin (Anti Diuretic Hormone- ADH), Aldosterone, etc.

Step 3: Tubular secretion: During urine formation, tubular cells secrete substances like ammonia into the filtrate. These substances are carried over by urine. Thus tubular secretion plays an important role in urine formation as it helps in the maintenance of the ionic and acid-base balance of body fluids.

Do you find any difference between glomerular filtrate and urine from collecting tubules?

If someone suffers from diabetes, there is polyuria (frequent urine formation) why?

Have you heard of some abnormal constituents of urine that may develop in different diseases like Glycosuria, Haematuria, Bilirubinuria, etc?

Have you heard of ‘Kidney transplantation’

Accessory Excretory Organs Of Human

In addition to kidneys, man possesses additional structures which also function as excretory organs.

Skin (Sweat gland): Skin is the protective superficial layer of the body. It contains numerous sweat glands which secrete sweat. Sweat glands are coiled unbranched tubular glands. The ducts of these glands open into the surface of the skin through which sweat is eliminated. Sweat contains different excretory products like urea, lactic acid, creatinine, uric acid, ammonia, NaCI, sulfate, etc. All these excretory products, along with water are excreted. The small sweat gland is the eccrine sweat gland and the large sweat gland is the apocrine. The mammary gland is a modified apocrine sweat gland.

Lungs: Cellular metabolism produces CO₂ which is a harmful (toxic) substance. CO₂ which is produced by the catabolic process of respiratory substrate (glucose) in the cell reacts with water and forms carbonic acid (CO₂ + H₂0 → H₂CO₂) which causes acidosis in the body. This condition is harmful to the body, hence CO₂ is regarded as an excretory product. This CO₂ along with water vapor and some volatile substances like alcohol, acetone, and ammonia is excreted during expiration through the lungs.

Liver: Ammonia is produced in the liver during protein metabolism. It is the most poisonous waste product. The liver converts this harmful ammonia into the relatively less harmful excretory substance called urea.

The conversion of ammonia to urea takes place by ornithine cycle or urea cycle in the liver. The liver excretes certain heavy metals, cholesterol, and bile pigments through bile.

Difference between Plant excretion and Animal excretion :

Levels Of Organization Of Life

Biomolecules And Heir Behaviour

Inorganic Compounds

Water: Water is the principal fluid medium of a cell. Nearly 70 to 85 per cent of the cell is water. Many cellular chemicals are dissolved in water others are suspended in water as solid particles.

• Chemical reactions take place among dissolved or suspended particles.
• Water concentration of the body is directly related to the age and metabolic activity of an organism Of the total body weight, the approximate percentage of water is as follows
• In newborns 78% by one year of age 65% in adult males 60% in adult females 55%.

Sources:

1. Exogenous water From food and drink.
2. Endogenous water (metabolic water) From the end product of metabolic reactions.
3. Endogenous water may be intracellular and extracellular.

Do you identify some examples of extracellular water in your body?

Physiological homeostasis of water: It is the process of maintaining a balance between fluid intake and fluid loss.

• Fluid intake is primarily by drinking water together with the intake of other liquid materials (for example milk etc). On the contrary, water loss may take place as follows:
• 15 ml/minute by respiration; 500 ml or day by sweat (of course, it depends upon temperature and humidity); 1000 -1500 ml/day by urine; little amount or day by stool.

Read and Learn More Class 9 Life Science

Can you explain why a patient in a hospital is given saline?

What does water do for you?

Importance of Functions of water:

Life can not exist without water. It has versatile functions in the body and life processes:

1. It is a universal solvent for all chemical and physiological reactions.
2. Water maintains electrolyte balance and acid-base balance of body fluids.
3. It allows the body’s cells to grow, reproduce and survive.
4. It is the major component of different body parts.
5. It acts as an important medium for osmosis, diffusion, filtration, transport and other physical processes.
6. It helps to deliver O₂ all over the body and transport CO₂
7. In digestion, it keeps the mucosal membrane moist; makes food bolus; dilutes food for enzyme action; synthesis digestive juice; medium for digestion; absorption of digested food.
8. It provides a medium for all metabolic reactions.
9. It lubricates joints.
10. It regulates body temperature by sweating and respiration.
11. It helps in detoxification and elimination of excretory products.
12. It acts as a shock absorber for the brain and spinal cord.
13. It is needed by the brain to manufacture hormones and neurotransmitters.

Acids: A hydrogen ion is a single free proton released from a hydrogen atom

Acid Definition: Molecules containing hydrogen atoms that can release hydrogen ions involutions are referred to as acids.

Example: HCl (Hydrochloric acid) ionizes in water to form hydrogen ions (H⁺) and chloride ions (Cl). Similarly, H₂CO₃ (Carbonic acid) ionizes in water to form H⁺ and HCO₃.

• Some common organic acids in the human body are HCI in the stomach, H₂CO₃ in the blood etc.
• ‘One apple a day keeps the doctor away’ justifies the statement.
• Prepare a list of organic acids and their functions in plants, animals and microbes.
• (Malic Acid in apple, in tamarind,oiUyteSfljrd in lemon, etc.)

Bases

Bases Definition: A base is an ion or a molecule that can accept an H₄ example. HCO₃” is a base because it can combine with H⁺ to form H₂CO₃. Similarly, HP04“ is a base because it can accept an H⁺ to form H₂P0₄“.

• ‘Do you know? “The protein in the body also function as bases because they readily accept H⁺. example. the protein Haemoglobin in RBC and proteins in other cells of the body are the most important bases of the body.”
• Can you identify some organic bases in plants and animals with their respective functions?
• In the human body, acid-base balance (buffer) is normally regulated by buffering agents in the respiratory system and the renal system.

Salts

Only six nonmetallic essential elements carbon, hydrogen, nitrogen, oxygen, phosphorus and sulphur, make up most of the body weight (98%) of an organism.

• Various metals and nonmetals combine to form different salts that are present in all living cells.
• Inorganic and organic salts of Ca, Mg, Na, K, and Fe, are very common in living cells.
• Prepare a list of Inorganic and organic salts known to you, that are present In plant and animal cells.

Gases

Three important gases needed by all living organisms are oxygen (20-4%), carbon dioxide (0 03%) and nitrogen (78%).

1. Oxygen is needed for aerobic respiration in different plants and animals. In terrestrial animals, O₂ – CO₂ exchange takes place through the trachea in insects, and the lung alveoli in man. Aquatic animals can absorb dissolved 02 for respiration through gills. Terrestrial plants absorb Op from the air for respiration both day and night and aquatic plants absorb dissolved O₂. O₂ is a gas that can be directly absorbed both by plants and animals.
2. Carbon dioxide is released by animals and plants during aerobic respiration. CO₂ is absorbed by green plants during photosynthesis. Terrestrial plants absorb CO₂ from the air whereas aquatic plants absorb dissolved O_2-CO₂ is a gas that can be directly absorbed only by plants but not by animals.
3. Nitrogen can be directly absorbed neither by plants nor by animals Nitrogen is fixed by blue-green algae (for example Nostoc, Anabaena), and N₂-fixing bacteria (for example Azotobacter, Rhizobium etc) because they contain some essential N₂-fixing enzymes. However, these enzymes are absent in higher plants and animals— so they can not fix nitrogen. N₂ is the essential component of various biomolecules like proteins, nucleic acid etc.

Organic Compounds

All living organisms are made of different organic compounds that are again formed of various inorganic elements like carbon, hydrogen, oxygen, nitrogen etc. All the carbon compounds that are obtained from living tissues are called ‘biomolecules’.So living bodies are a mixture of inorganic and organic substances or molecules.

Smaller Molecules Micromolecules

A small molecule is a low molecular weight (less than 900 Dalton) organic compound, soluble in acid. (Dalton is the unit of molecular weight of biomolecules, which signifies the weight of 1 atom of hydrogen). They have tremendous importance in biological functions. Some common examples of smaller molecules are monosaccharides, amino acids, fatty acids, nucleotides etc.

Simple Sugars

• Simple Sugars Definition: Simple sugars (as the name suggests) are the simplest form of carbohydrates that act as primary sources of energy in the human body e.g. monosaccharides.
• Monosaccharides: They contain only one unit of simple sugar example Glucose, fructose, galactose etc. Fructose is the sweetest natural sugar.
• Basic Structural Features: Colourless crystalline compounds, sweet. They undergo fermentation by yeast and other microorganisms.
• Source: Glucose (Dextrose) in grapes; Fructose (Laevulose)- fruit sugar which is present in almost all sweet fruits, honey; Galactose- it does not occur free in nature. In the body, galactose is present as a component of milk sugar (Lactose) which is formed of glucose and galactose.

Try to answer why is glucose called aldose and fructose as ketose. Galactose is absorbed fastest in the body through the small intestine.

Prepare a list of fruits that taste sweet.

Can you explain: Why a green mango is sour but becomes sweet as it is ripened?

Major Role In Life Processes

• Glycolysis:  Glucose undergoes glycolysis to produce pyruvic acid in cell cytoplasm.
• Storage: Excess. glucose may be converted into starch in plants, and glycogen in animals.
• Maintenance of blood sugar: Normally 100 ml of human blood contains 80-120 mg of glucose. An increase of this glucose level results in hyperglycemia (Diabetes mellitus) whereas a decrease in glucose level is called hypoglycemia.
• Synthesis of fats, and proteins:  By various metabolic reactions in the liver excess glucose may be converted to fatty acid, glycerol, amino acids etc.
• What will happen if someone eats a huge amount of rice daily without doing much work?

Amino Acids

They can be variously classified (Classification details will be discussed in higher classes). However, the basic classification is as follows:

• Acidic amino acid: ExampleAspartic acid, Glutamic acid
• Basic amino acid: Example Arginine, Lysine etc.
• Neutral amino acid: Example Glycine, Alanine etc..
• Essential amino acid: Example eight amino acids that are not synthesized in the human body and are taken along with diet example Valine, Histidine, methionine, Phenylalanine, Leucine, Isoleucine, Tryptophan, and Lysine.
• Non-essential amino acid: The remaining 12 amino acids are synthesized in the liver of the human body example Glycine, Alanine, Serine, Cystine etc. Glycine is the simplest amino acid
• Source: All amino acids are present in the protein. Essential amino acids are generally obtained from animal protein (for example egg, meat, fish, milk) and a few plant proteins.

Role In Life Processes

1. Structure and Function of protein: Since protein is made of different amino acids, the structure and function of a protein depend on its component amino acids.
2. First class protein: The protein that contains all essential amino acids and is capable of growth and maintenance example Albumin, globulin proteins of egg, meat, fish, milk etc. (Almost all animal proteins are first class proteins).
3. Second class protein: The protein that contains few essential amino acids but not all and is not suitable for growth and maintenance example Zein of Maize (Most plant proteins are second class proteins),

Fatty Acids

Basic Structural Features

• The fatty acid has a carboxyl group (COOH)attached.
• It is insoluble in water but soluble in fast solvents like chloroforms ether alcohol etc.

Types:

1. Saturated fatty Example: Stearic acid palmitic acid etc
2. Unsaturated fatty acid Example: Oleic acid Crotonic acid.
3. Essential fatty acids are needed for normal growth but are not synthesised in the body so they are taken along with diet Linoleic acid Linoleic acid and Arachidonic acid.

Source: Stearic acid in animal lard palmitic acid in palm oil, milk, meat, butyric acid in milk butter etc, oleic acid in olive oil, animal fat etc.

Do you know that Oleic acid is the most abundant fatty acid in human adipose tissue?

Role In Life Processes :

1. They help in the normal growth of the body
2. They are structural components of cells.
3. They are responsible for normal reproductive functions.
4. They are necessary for healthy skin.

Difference Between Amino Acid and Fatty Acid.

Nucleotide

Nucleotide Definition: Nucleotide is the structural unit of nucleic acid (DMA and RNA). Deoxyribonucleotide is the structural unit of DNA and ribonucleotide is the structural unit of RNA.

Basic Structural Features

One nucleotide consists of a pentose sugar (5-c-sugar), Nitrogenous base (N-Base) and phosphoric acid (H3P04).

1. N-Base can be of – Purine [Adenine (A) and Guanine (G)) and Pyrimidine [Thymine (T), Cytosine (C) and Uracil (U)].
2. A, T, G and C are present in DNA whereas A, U, G and C are present in RNA.
3. Nucleoside consists of pentose sugar and nitrogenous base without H₃P0₄.

Source: Nucleotides are present in Nucleic acid.

Role In Life Processes: DNA and RNA function as genetic material and they consist of nucleotides only.

(How can you explain the term ‘genetic material’ ?)

ATP (Adenosine Tri Phosphate): It is a nucleoside triphosphate used in cells. It is often called the “molecular unit of currency” or “energy currency” of intracellular energy transfer.

• ATP provides chemical energy within cells for various metabolic reactions.
• It is one of the end products of photophosphorylation, cellular respiration, and fermentation.
• ATP is highly soluble in water and one molecule of ATP contains two high energy bonds. A- P – P – P

High energy bond

ATP→ ADP + Pi + energy

ATP → AMP + PPi (Pyrophosphate) + energy.

Synthesis: ATP is synthesised partly in glycolysis, partly in the Krebs cycle but mainly in the electron transport chain (ETC).

Macromolecules

Macromolecules Definition: Those organic compounds that are acid insoluble, having molecular weight- of more than 300 Dayton (except lipid) are called macromolecules.

• They are complex carbohydrates (oligo-and polysaccharides), proteins, lipids and nucleic acids
• . (However, though lipid is considered a biomacromolecule, it has a molecular weight of less than 900 Dalton).

Complex Carbohydrates

Complex Carbohydrates Definition: Complex carbohydrates are oligosaccharides (disaccharides, trisaccharides etc) and polysaccharides. They are formed of two or more monosaccharide units interlinked glycosidic bends.

Disaccharides: They are formed by the combination of two monosaccharide units with the elimination of one molecule of water.

• Lactose (in milk) is formed of glucose and galactose :
• Sucrose (cane sugar) is formed of glucose and fructose;
• Maltose (malt sugar) is formed of glucose and glucose (i.e. two molecules of glucose)

Do You know the name of the bond between two glucose molecules?

• Trisaccharides: They are formed by the union of three monosaccharide units. (Can you explain how many water molecules will be released in this structure ?) Raffinose (found in beans, cabbage, broccoli etc) is formed of glucose + fructose + galactose.
• Tetrasaccharides: This is formed of four monosaccharide units, e;g. Stachyose (found in green beans, soybeans etc.) is formed of two molecules galactose + glucose + fructose.

More Complex Carbohydrates Or Polysaccharides

Polysaccharides are polymers of a large number of monosaccharide units (monomers). Polymer is the ‘garland’ whereas monomer is the ‘individual flower’ of the garland, example Glycogen is the polymer and each glucose unit is the monomer.

Basic Structural Features

1. They are commonly not sweet.
2. Generally, they are soluble in water (except cellulose)

Some Common Polysaccharides

Starch: Polymer of glucose, produced by plants; insoluble in cold water gives a blue colour with iodine tasteless.

Glycogen: Found in animals and fungi, Known as ‘animal starch’ soluble in water, gives a reddish colour with iodine.

Cellulose: Found in plants; insoluble in water; taken in the body along with vegetables; can not be digested in the human body and forms ‘roughage’ (Roughage is the undigested food materials, mainly formed of fibres, that go out along with stool and prevents constipation). Cellulose is the most abundant carbohydrate in nature and starch is the second most abundant carbohydrate.

Role In Life Processes

1. Starch is the main constituent of food grains.
2. Glycogen (animal starch) is generally stored in the liver and muscle as a food reserve.
3. Cellulose forms ‘roughage’, stimulates peristalsis and helps in defecation.
4. Carbohydrate (Simple or complex) is the main source of energy when completely oxidised. One gram of carbohydrate yields 4-0 Kcal energy.

Protein

Protein Definition: Protein is the polymer of amino acids that are interlinked by peptide bonds

For reference only: The protein which is present maximum in the world is a plant enzyme protein called RuBisCO (Ribulose Bis phosphate carboxylase oxygenase)

• which plays a key role in the dark reaction of photosynthesis in the stroma of chloroplast.
• But the animal protein present maximum in the world is collagen.

Basic Structural Or Compositional Features

An essential component of protein is nitrogen.

1. “I ne structural unit of protein is an amino acid.
2. Most of the proteins have a fishy smell.
3. When heated, protein coagulates (You have seen if milk is heated, it gradually condenses).
4. In an acidic medium, protein is precipitated.

Source: In plant products like soybeans, pulses, different seeds etc. Animal products like milk, eggs, fish, and meat are rich sources of animal protein.

Role in life process :

• Body-building food: Protein is the chief organic constituent of the protoplasm of a living cell. So it is called as body building food.
• Maintenance of body: Protein helps to maintain body structure, body growth, repair of damaged tissues due to wear and tear, storage of proteins etc.
• Synthetic function: It helps in the synthesis of plasma proteins (albumin, globulin, prothrombin, fibrinogen etc.) haemoglobin, enzymes, most animal hormones, milk protein (lactalbumin, lactoglobulin) antibodies (Immunoglobulin), melanin pigments etc.
• Calorific value: One gram protein when completely oxidised yields about 4.1 Kcal energy.
• Enzyme Definition: Enzymes are biological catalysts, or proteins in nature, produced by living cells, that accelerate various biochemical reactions, but themselves remain undestroyed after the reaction.

Basic Compositional Features

1. Nature:  Almost all enzymes are proteins.
2. Structure:  Like all other proteins, the enzyme is also formed of several amino acids.
3. Active site: We ingest food through our mouth, so the mouth is the ‘active site’ for ingestion. Similarly, the enzyme also performs its function by the ‘active site’ at a higher rate.
4. Specificity: Each enzyme acts on a specific substrate eg. Protease acts only on protein; lipase acts only on lipids etc.
5. Catalytic property enzymes act as biocatalysts, they are not destroyed at the end of the reaction.
6. Medium (pH): Each enzyme acts in a definite medium eg. ptyalin of the buccal cavity in a neutral medium, pepsin in the stomach in an acidic medium, trypsin in the small intestine in an alkaline medium and so on.
7. Temperature: Enzyme shows maximum activity in optimum temperature (35°C-40°C). At BSP temperature (above 40°C) enzyme may get damaged (denaturation).
8. Action:  Enzyme action is reversible and may be inhibited by a suitable inhibitor.
9. Components: The enzyme consists of two parts: apoenzyme (Protein part of enzyme) and coenzyme (non-protein part) or cofactor. Apoenzyme and coenzyme (cofactor) together form the functional enzyme called Holoenzyme.

Holoenzyme = Apoenzyme + cofactor or coenzyme.

Types of enzymes:

Digestive enzyme: Enzymes taking part in digestion are called digestive enzymes.

They Are Three Types

1. Proteolytic enzymes or Protein-hydrolysing enzymes: These enzymes hydrolyse proteins into polypeptides and amino acids, for example, Pepsin, Trypsin, Chymotrypsin, Erepsin, and Renin.
2. Lipolytic enzymes or Lipid hydrolysing enzymes: These enzymes hydrolyse lipids (fats) into fatty acid and glycerol example Lipase (Gastric Lipase, Pancreatic Lipase, Intestinal lipase).
3. Amylolytic enzymes or Carbohydrate hydrolysing enzymes: These enzymes hydrolyse the carbohydrate into monosaccharides (glucose), for example, Amylase, Sucrase, Lactase, Maltase, etc.

Bile does not contain any digestive enzyme but it breaks down bigger molecules of fat into smaller droplets to increase the surface area for action of lipase. This is called the emulsification of fat.

For reference only Functional classification: According to the type of reaction, enzymes are also classified into 6 types

1. Oxidoreductase,
2. Transferase,
3. Hydrolase,
4. Lyase,
5. Isomerase, and
6. Ligase.

Role In Life Processes:

1. Enzymes accelerate different biochemical reactions.
2. They are essential for any metabolic reaction in living organisms.
3. They play a very significant role in digestion.

Do you know, there is a very special type of enzyme called allosteric enzyme?

Lipid and Fat

Lipid and Fat Definition: Fat is the fatty acid of glycerol. The salt of alcohol (glycerol) with organic acid (fatty acid) is known as ester. Lipid is a broader term which includes fat, wax, cholesterol, and hydrocarbon since all of them are insoluble in water but soluble in organic solvents. Hence all fats are lipids but all lipids are not fats.

Basic Structural Or Compositional Features

They are insoluble in water but soluble in ether, chloroform etc.

1. At ordinary temperatures, some fats remain solid (for example lard) whereas others are in liquid form.
2. Unsaturated fats are generally liquid. Those fats which remain liquid at ordinary temperature are called oils.
3. Some common plant oils are mustard oil, groundnut oil, coconut oil, soyabean oil, sunflower oil etc.
4. Some oils from animals like cod liver oil, shark liver oil, etc. are rich sources of vitamins A and D.
5. They are lighter than water so float on the water’s surface.

Source:

• Plant source: Mustard oil, coconut oil, groundnut oil etc.
• Animal source: Meat, milk and milk products like ghee, butter, cheese etc,

Role In Life Processes :

1. Calorific value: Lipid provides a food with high calorific value. One gram of lipid produces about 9’3 KCal energy.
2. Storage: Lipid acts as reserve food material because it can be easily stored in the body for future use.
   • (Do you know, which tissue of man’s maximum fat is stored )
3. Reaction: The storage (depot) fat protects the vital organs, skin etc. and also acts as cushion and packing tissues.
4. Heat insulations: Lipid acts as an insulator. Thus subcutaneous fat helps to regulate body temperature (thermoregulation).
   (Find out the blubber in Whale and its major function)
5. Solvents: Lipids a good solvents for fat-soluble vitamins like vitamins A, D, E, and K.
6. Hormone synthesis: From cholesterol, all steroid hormones are synthesized in animals.

Nucleic Acids

Nucleic acid Definition: Nucleic acid is the polymer of nucleotides (polynucleotides). They are distributed in the nucleus and cytoplasm of a cell.

Basic Structural Features

DNA (Deoxyribonucleic Acid) (Do you know the structure of DNA was discovered by Watson and Crick for which they were awarded the Nobel Prize.)

1. It is usually double-stranded or double-helical. (Can you mention an exception where single? stranded DNA is present)
2. Two complementary chains are named a (alpha) and β (Beta).
3. Two chains are antiparallei and interlinked by H-bonds.
4. The structural unit of DNA is called deoxyribonucleotide which consists of pentose (deoxyribose) sugar, H₂PO₄ and N-Base. .
5. N-Base can be of two types purine and pyrimidine.
6. Purine of DNA is again of two types Adenine (A) and Guanine (G) whereas pyrimidine is again of two types Thymine (T) and Cytosine (C).

RNA (Ribo Nucleic Acid)

1. It is generally single-stranded or single-helical.
2. If you can identify an exceptional organism which contains double-stranded RNA!
3. The structural unit of RNA is ribonucleotide which consists of a pentose sugar (ribose), H3P04 and N-Base.
4. N-Base can be of two types Purine and Pyrimidine.
5. Purine in RNA is of two types Adenine (A) and Guanine (G) whereas
6. pyrimidine is again of two types Uracil (U) and Cytosine (C)

Source: Nucleic acid is present in all living plant cells, animal cells, microbes, viruses etc (though there are very rare exceptions)

Role In Life Processes

DNA: It contains genes and is responsible for the inheritance of characteristics from parents to offspring.

• It is responsible for all characteristics of an organism.
• It controls cell division where a mother cell divides itself to produce two daughter cells.

RNA: In plant viruses TMV (Tobacco Mosaic Virus) and in some animal viruses like Influenza virus, HIV (Human Immunodeficiency Virus) etc.  RNA contains genes so RNA is the genetic material in them.

• mRNA (Messenger RNA) carries information from DNA and helps in protein synthesis.
• tRNA (Transfer RNA) collects amino acids from cell cytoplasm for protein synthesis.
• rRNA (Ribosomal RNA) is the structural component of ribosomes and helps in protein synthesis.

Difference between DMA and RNA

Role Of ATP As Energy Currency Of A Cell

ATP (Adenosine Tri Phosphate) is the primary molecule for storing and transferring energy in cells. It is often referred to as the “energy currency of the cell” and may be compared to storing money- (ATP) in a bank (cell).

• In any energy-related biochemical reaction of the cell, ATP is either produced or consumed.
• For example, during photosynthesis, ATP is synthesized (photophosphorylation) by using solar energy whereas during respiration, ATP is synthesized through glycolysis, Krebs cycle, ETC.
• The production of ATP in ETC is known as oxidative phosphorylation.
• ATP is a nucleotide consisting of an N-Base [Adenine (A)], attached to a ribose pentose sugar (5-sugar), which is attached to three phosphate groups, that are linked to one another by two high-energy bonds.

ATP: Adenosine – P – P – P

(N- Base)

The symbol – designates a high-energy bond. So, in 1 ATP, there are 2 high-energy bonds.

When these high-energy bonds are broken, energy is released, which is utilized for any biochemical reaction of the cell or body.

ATP ADP + Pi + energy

ATP AMP + PPi + energy

Vitamins And Their Roles In The Human Body

Vitamins And Their Roles In The Human Body: The word vitamin was suggested in 1912 by Casimir Funk.

• He isolated a concentrate from rice polishings which was found to contain nitrogenous bases (amines).
• As these substances were vital for sustaining life, they were called vitamines ( vita, life).
• Later, when it was discovered that all these essential substances were not exclusively amines, the letter ‘e’ was dropped and then the name vitamin was given by J. C. Drummond.

Health And Life Definition: Vitamins are organic compounds present in variable minute quantities in natural foodstuff which are required for normal growth as well as maintenance of health and life.

Importance (Functions) of Vitamins: Vitamins are needed to resist diseases, as they act as protective principles of food.

General Characteristics Of Vitamins

Vitamins are obtained from plant products and animal products.

• The daily requirement of vitamins is very low.
• A small amount of fat-soluble vitamins may be stored in the liver and vitamin C in the adrenal cortex. However, most of the vitamins can not be stored in the human body.
• Vitamins are destroyed after reaction hence they must be supplied to the body regularly.
• Some of the vitamins are heat stable (for example vitamins A, D, E, K, B₂ etc) but some of the vitamins are heat-louble (for example vitamins B₂, B₃, vitamin C etc).
• Vitamins are not synthesized in the human body. It must be supplied to the body along with diet.
• However, a small amount of vitamin A is synthesized in the human liver from carotene pigments.

Source Of Different Vitamins 

Minerals And Their General Role In The Human Body

Minerals And Their General Role In The Human Body: Various minerals are needed to maintain vital functions of our body like enzyme activity, hormonal functions etc. They are essential components for cellular biomolecules, the structure and function of cells and so on.

Macromineral Definition: The minerals that are present: in higher levels in the human body and are required in relatively larger amounts in the diet are called macromineral.

Micromineral Definition: The minerals that are present at low levels in the body or required in smaller amounts in the diet are known as micromineral. They are sometimes also called essential trace minerals.

Role Of Micromineral In The Human Body

Cell

Have you seen the brickworks in the construction of a building? You will observe the arrangement of bricks that are placed one above the other and side by side. So, the bricks are structural units of a building.

• Similarly, the living body of plants and animals is made up of certain tiny (usually microscopic) structural units called cells. Generally, most of the organisms that are commonly visible to us are multicellular they are composed of many cells.
• A vast number of organisms are there that are formed of only a single cell, called unicellular organisms.
• The single cell exhibits all the characteristics of life and maintains its independent existence.

Discovery of cell

The term “cell” was first used by Robert Hooke, an English engineer, in 1665. While he was examining a section of bottle cork under a microscope, he saw many honeycomb-like empty chambers (hollow spaces) in it.

• He named each of these hollow spaces as cells. Hooke used a very simple type of self-made compound microscope.
• After he discovered cells, considerable progress was made in the development of powerful and more sophisticated microscopes that reveal details of cytology.
• Do you know what is meant by ‘cytology’? Have you heard the name of an electron microscope (EM) where maximum magnification is possible?

What is a Cell

Cell Definition: A ceiling may be defined as the structural as well as functional unit of a living organism.

Size of cells: Cells are usually small in size and are not visible to the naked eye. Different parts of the cell can be viewed under a microscope.

• But a few cells are quite large and are thus visible even to the naked eye.
• RBC is the smallest cell of the human body. What: ‘s the largest cell? in the human body?
• Do you know the ostrich egg is the largest single cell on the earth?
• Elementary idea about structures and functions of different cell components :

Cell Wall

Cell Wall Definition: The thick rigid, porous, permeable non-living, outer envelope of plant cells made up of cellulose is called the cell wall.

Most plant cells (but not animal cells) have a cell wall. It is lying just outside the cell membrane.

• Structure: The main constituent of the cell wall is cellulose, a type of carbohydrate. The cell wall of a mature plant cell consists of two parts
• Primary cell wall: It is the outer permeable and thinner wall in comparison to the secondary cell wall.
• Secondary cell wall: It is the thicker inner part of the cell wall formed after the primary cell wall.
• It has three layers thin outer layers thick middle layers and thin. The common host-formed wall lying between the two adjacent cells is called the There are sonic minute pores present in the cell wall through which protoplasmic connections between the adjacent cells arc established. These intercellular connections are known as plant cells.

Cell Wall  Functions:

1. The cell wall gives shape and rigidity to the cell.
2. It protects the protoplasm from external injury.
3. Unless deposition of special chemical substances occurs (as in the cells of bark), the cell wall is freely permeable to the molecules i.e. allows them to pass through in and out freely.
4. The plasmodesmata are meant for cell-to-cell conduction of water and different chemical substances.

Cell Membrane or Plasma Membrane Plasmalemma

Cell Membrane Or Plasma Membrane Definition: The thin flexible semi-permeable living membrane that surrounds the protoplasm of a cell is called the cell membrane or plasma membrane.

• The cell membrane lies as the external covering layer of animal cells.
• However, in plant cells, the membrane lies between the protoplasm and the cell wall.

Structure: Thccellmcmbrane is a thin limiting membrane. Under an electron microscope (EM), the cell membrane is found to be made up of three layers a layer of lipid is present between two protein layers. Such a membrane is called the unit membrane (P-L-P) by J. D. Robertson.

Different models related to the structure of cell membranes have been proposed by various scientists of which the most accepted one is the Fluid Mosaic model as proposed by Singer and Nicolson(1972)

Do you know the Fluid Mosaic Model represents floating icebergs of protein in the seawater of Lipid?

Cell Membrane Or Plasma Membrane Functions :

1. The cell membrane protects the protoplasm and the cell organelles from external injury.
2. It maintains the normal structure of the cell.
3. It retains the cell contents and controls the transfer of food materials and waste products inside and outside the cell respectively.
4. It allows the entry and exit of selected molecules.
5. Cell membrane gives mechanical support.

Protoplasm (Protos = First Plasma = Shape)

Protoplasm is a translucent jelly-like viscid material constituting the essential substance of living cells. Protoplasm = Cytoplasm + nucleus.

• Max Schultze and Thomas Huxley proposed protoplasm as the physical basis of life.
• Because all the vital functions like nutrition, secretion, growth, reproduction, irritability, mortality etc. of the living cells are controlled by the protoplasm.
• It is made up of cytoplasm and nucleus. The term protoplasm was coined by Purkinje. The protoplasm exhibits streaming movement called cyclosis or Brownian movement.

1. Cytoplasm Definition: A thick, semi-transparent, elastic fluid containing suspended particles and a series of minute tubules and filaments is known as cytoplasm. Cytoplasm is the matrix or ground substance which is present between the cell membrane and the nuclear membrane of the cell. Cytoplasm = Protoplasm – nucleus
2. Structure: Under the ordinary compound microscope the cytoplasm appears to be.a semi-fluid, apparently transparent and homogenous substance. The outer denser portion of the cytoplasm is known as the ectoplasm. It is a relatively non-granular and transparent part. The inner less denser portion is lying towards the nucleus and is called the endoplasm. It is granular and viscous. The fluid part of the cytoplasm is known as the hyaloplasm or cytoplasmic matrix. This fluid part contains various cell organelles (mitochondria, Golgi bodies, endoplasmic reticulum, chloroplasts etc!), non-living inclusions and vacuoles. Hyaloplasm = Cytoplasm – cellular organelles.

Protoplasm Functions :

1. Various cytoplasmic organelles, the nucleus and non-living cytoplasmic inclusions remain embedded in the cytoplasm
2. The cytoplasm is the site of several chemical reactions which are essential for life (e.g. part of respiration).

Cytoplasmic Organelles

Cytoplasmic Organelles Definition: The tiny specialized subunit of a cell which remains embedded in the cytoplasm having a specific physiological function of the cell is called cytoplasmic organelles. Thus the relation between organ and body is similar to organelle and cell.

Examples—Nucleus, mitochondria, plastids, Golgi bodies, centrosomes, ribosomes, endoplasmic reticulum, lysosome, vacuole etc. are such structures.

Nucleus Definition: The double membrane-bound dense spherical protoplasmic body (largest cellular organelle) containing chromosomes is called the nucleus.

The nucleus is usually present at the centre of the cell, but in mature plant cells, it is pushed towards the periphery by the vacuole. Generally, a single nucleus is present in most cells (uninucleate). In some cases, however, more than. one nucleus may be present in each cell (multinucleate).

Examples: skeletal muscle, certain algae and fungi. In bacteria organised nucleus is absent.

Human mature erythrocytes and plant’s sieve tube (cell) do not contain a nucleus. So they are non-nucleated living animal cells and plant cells respectively.

Structure: The nucleus is a specialized protoplasmic denser body lying embedded in the cytoplasm. Under a powerful microscope, the nucleus shows the following parts

Nuclear membrane: The porous delicate double membrane-bound structure which surrounds the nucleus is called the nuclear membrane. The space between two membranes is called perinuclear space. Functions The nuclear membrane separates the nucleus from the surrounding cytoplasm.

Nucleoplasm or Nuclear sap: it is a dense but clear fluid present in the nucleus, forming the matrix. Functions. It stores reserve materials that are used up at the time of the cell division.

Nuclear reticulum: Suspended in the nuclear sap there lies. an irregular network of delicate threads called the nuclear reticulum or chromatin reticulum. Functions During cell division, thread-like bodies, called chromosomes are developed from this reticulum. They contain the hereditary material (DNA and genes) and control the characteristics of the organism.

Nucleolus: The highly retractile, dense and non-membranous spherical body present within the nucleus is called the nucleolus. Functions Nucleolus helps in the formation of ribosomes. It also helps in the synthesis of ribosomal RNA and protein.

Functions Of Nucleus:

1. The nucleus is thought to be the centre of all chemical activities of the cell- the so-called brain of the cell
2. It acts as the controlling centre of the major physiological processes taking place within the cell,
3. It contains chromosomes the bearers of hereditary characters called genes and helps in the transmission of these hereditary characteristics from parents to offspring,
4. It also initiates and regulates the cell division.

Mitochondria (sing Mitochondrion)

Mitochondria Definition: The spherical or elongated double membrane-bound filamentous cytoplasmic bodies associated with cellular respiration are called mitochondria. Mitochondria appears throughout the cytoplasm of all living cells except the prokaryotic cells like blue-green algae and bacteria, as well as the matured erythrocytes of mammals.

Structure: The oval or rod-like mitochondria possess two unit membranes. The outer membrane of the mitochondria is smooth but the inner membrane remains folded inwards to form finger-like projections at several points to form several partitions or shelves called cristae (sing, crista).

On the wall of cristae of mitochondria, there are numerous particles called elementary particles, or Fa particles. The two membranes lie apart from each other and the space between them is filled up with a fluid. The central cavity of the mitochondrion is enclosed by the inner membrane and cristae is filled up with a ground substance called Matrix.

Function: The mitochondria are associated with cellular respiration. During respiration food is oxidized and a considerable amount of energy is liberated in the form of ATP. As mitochondrion acts as a source of energy generator, it is regarded as the ‘power-house of the cell’.

Plastids Definition: The pigmented or non-pigmented double membrane cytoplasmic bodies in ant cells associated with the preparation or the storage of food materials are called plastids.

Plastids are present in the cytoplasm of most plant cells. The plastids do not occur in the cells of bacteria, blue-green algae, fungi and animals (except for Euglena).

Plastids Are Of Three types

1. chloroplasts,
2. chromoplasts and
3. leucoplasts.

Different Types Of Plastids

EES Chloroplasts: (Gr. Chloro = green; plastos = formed): Green-coloured plastids are called chloroplasts. They are found in most green parts of plants, such as foliage leaf, young stem, calyx of flower etc.

Structure: The chloroplasts are double membrane-hound structures containing granular bodies known as the grana and a ground substance of fluid nature called the stroma. Each granum is made up of a stack of minute bag-like structures, each of which is called a  Green photo or synthetic pigment, called chlorophyll, which is present in high concentration in the thylakoids. They also contain other photosynthetic pigments, such as orange carotene, yellow xanthophyll etc.

Plastids Function —The chloroplasts are meant for photosynthesis. Chlorophyll is present in the thylakoid of grana of the chloroplast.

Chromoplasts :(Gr. Chrome = colour; lists = formed); The plastids having colour other than green are called chromoplasts. Chrornoplastids are found in the cells of five petals, fruit skin, coloured roots (for example carrot) etc.

• Structure: It is almost similar to that of the chloroplasts but they contain membranous tubes instead of thylakoids. It contains pigments like carotene, /xanthophyll etc. but never chlorophyll.
• Functions: It attracts insects for pollination and imparts various colours to the various plant organs like petals, fruits etc.

Do you know which pigment in the petals of a rose makes the flower so beautiful? The flower of jasmine has a fantastic smell—try to discover which chemical is it.

Leucoplasts : (Gr.Leuco white; plastics – formed); The colourless plastids are called the leucoplasts. leucoplast is found in roots, underground sterns (for example potato) etc.

• structure: I leucoplasts are double membrane-bound rod-like or sphere-shaped colourless plastids.
• Functions: leucoplast can be converted to chloroplasts on exposure to sunlight and reconverted to leucoplast when kept in the dark for a long time, fhe leucoplasts are concerned with the storage of food materials like carbohydrates (starch), protein, and lipids within the cell.

You have observed that a young leaf Is green, but as It becomes old, it turns yellow why  Similarly skin of an unripe mango Is green In colour but as It Is ripened, It turns orange and yellow try to find the answer yourself.

If a piece of beet is placed In water, the water turns red but if a piece of carrot Is placed In water, water does not turn yellow how can you explain It?

Endoplasmic Reticulum

Endoplasmic Reticulum Definition: fhe membrane-bound channels of various shapes form Irregular nH work In the cytoplasm Is called endoplasmic  (ER). The endoplasmic reticulum is present In all eukaryotic animal arid plant cells.

Structure: Based on its association with ribosomes ER is divided into two types. Granular (rough) RER or GER is studded with ribosome. Ribosomes are attached to the membrane of RER by a protein called ribophorin.

Agranular (smooth) SER is free of ribosomes. Agranular ER is synthesised from granular ER. Eachtypeofendoplasmicreticulum consists of inter-communicating narrow tubes, the tubules, a small spherical or oval sac-like structure, the vesicles and large flat sacs the cisternae. All these structures are filled up with fluid called endoplasmic matrix and are surrounded by a single lipoprotein membrane.

Endoplasmic Reticulum Functions :

1. Proteins are synthesized by ribosomes attached to the membranes of granular ER (RER)
2. The agranular ER (SER) synthesizes sterol, fats and phospholipids,
3. The ER is also involved in the intracellular exchange of materials between the nucleus and cytoplasm.

Golgi body :

Glogi Body Definition: The parallelly arranged membrane-bound cytoplasmic bodies occurring near the nucleus and participating in the secretory process of cells are known as the Golgi bodies.

• The Golgi bodies are abundant in animal cells and are less frequently found in plant cells.
• In plants, these organelles are called dictyosomes.

Structure: The Golgi bodies consist of four to eight thin membrane-bound flattened sacs, stacked upon each other like a pile of dishes with expanded areas at their end.

The stacked elements are called cisternae. In the peripheral part of cisternae small droplet-like sacs, known as the vesicles bulge out. They also possess vacuoles.

Glogi Body Functions :

1. Golgi bodies are associated with the secretory activity of the cell.
2. They help in the formation of plant cell walls, plasma membranes and secretory vesicles.
3. Do you know what are the major secretory substances of a cell?

Lysosome

Lysosome Definition: The single membrane-enclosed tiny spheroid or irregular vesicles containing hydrolytic enzymes which help in both intracellular and extracellular digestion are known as lysosomes. Lysosomes remain scattered in the cytoplasm of animal cells. The number increases in the secretory cells.

Structure: A mature spherical lysosome is surrounded by a lipoprotein membrane. Inside the membrane, finely granular regions of different densities are observed. Within it different hydrolytic enzymes are present. Lysosomal enzymes are called acid hydrolases.

Lysosome Functions :

1. Lysosome helps in cellular digestion
2. It helps in autolysis (digesting the various organelles of the cells) hence lysosome is called the “suicidal bag of the cell”.

Vacuole Definition: The single membrane-bound cavities containing a kind of watery fluid (cell sap) present within the cytoplasm are called vacuoles.

The vacuoles are considered one of the non-living bodies of the cell and contain stored food materials and certain secretory and excretory products. Vacuoles can occasionally be seen in animal cells but they are quite common and larger in plant cells.

Structure: In a young plant cell, several vacuoles are found. But as the cell matures the vacuoles fuse forming a large central vacuole which pushes the cytoplasm along with the nucleus against the cell wall. This peripheral layer of cytoplasm thus formed surrounding the vacuole is known as the primordial utricle. Each vacuole cell sap. A vacuole is surrounded by a single membrane similar to a plasma membrane called a tonoplast. The cell sap (Tonoplasm) may contain mineral salts, sugar etc. dissolved in water.

You should know that the fluid in the vacuole is called a tonoplast.

Vacuole Functions :

1. The vacuoles are of different types which perform different functions, such as
2. Food vacuole acts as the store-houses of water, mineral salts, sugar, etc.
3. Gas vacuoles store gases which helps the aquatic plant remain floating on the water,
4. Water vacuole formed by pinocytosis contains water
5. Contractile vacuole contains water which is expelled to the outside by its contraction and relaxation (for example Amoeba)
6. The excretory vacuole contains excretory products, gases, etc. and maintains cell turgidity.

Ribosome Definition: Ribosomes are non-membranous small, dense, round and granular particles of ribonucleoprotein. Ribosomes are present freely in the cytoplasm. The free ribosomes occur singly or in clusters (polyribosomes). The ribosomes also remain attached to the membranes of the endoplasmic reticulum, (bound ribosome), mitochondria, chloroplast etc.

Structure: A ribosome consists of two sub-units, one about half the size of the other. The larger sub-unit is dome shaped and the smaller sub-unit forms a cap-like structure. These two sub-units are situated to the flat surface of the other. In eukaryotic cells, the sub-units of the ribosome consist of 60S and 40S (jointly 80S). In prokaryotic cells, the sub-units of ribosomes consist of 50S and 30S (jointly 70S). The large unit is ‘cup-shaped’ and the smaller unit is ‘cap-shaped’. During protein synthesis, two units get interconnected by Mg++ ions. Ribosome of eukaryotic cell

Do you know that ‘S’ in ribosome stands for ‘sedimentation coefficient’ or Svedberg’s unit?

Ribosome Function: Ribosome helps in protein synthesis.

Centrosome Definition: In animal cells, two tiny hollow cylindrical Dodies, the centrioles, remain surrounded by a recognizable clear zone of cytoplasm and form a complex which is known as the centrosome. Centrosomes are generally present in animal cells and occasionally in the cells of some lower plants.

Structure: The centrosome consists of two parts the centriole and the centrosphere. The centrioles are usually two in number which are tiny cylindrical bodies arranged at right angles to each other. The centrosphere is the dense cytoplasm surrounding the centrioles.

Centrosome Functions:

1. Centrosome plays an important role in animal cell division
2. It also plays an important part in the formation of cilia and flagella.

Microtubule

Microtubule Definition: In the cytoplasm of eukaryotic cells, there are numerous non-membranous hollow cylinders known as microtubules.

Structure: Microtubules have variable length. They are formed of a special type of protein called tubulin. Each tubulin consists of two sub-units (dimer)

Microtubule Functions:

1. They form a supporting framework or cytoskeleton and give shape to the cell
2. Microtubules form spindle during mitotic or meiotic cell division
3. They form cilia and flagella which help in movement.

Prokaryotic and Eukaryotic cells

Prokaryotic cells Definition: A cell which lacks a nuclear envelope, nucleolus and well-defined cytoplasmic organelles, such as endoplasmic reticulum, Golgi body, mitochondria, centriole, etc. is known as a prokaryotic cell.

Examples: All Bacteria (Azotobocter, Clostridium), all Blue-green algae (Nostoc, Anabaena), Mycoplasma, etc.

Eukaryotic cell Definition: The cell which contains a true nucleus (nucleus covered by a nuclear membrane) together with well-defined cytoplasmic organelles like endoplasmic reticulum (ER), Golgi bodies, mitochondria, lysosome, etc. is known as a eukaryotic cell.

Examples: Cells of higher plants and animals.

Plant Cells and animal cells: Both plant cells and animal cells are eukaryotic cells They contain so many common organelles like the nucleus mitochondria, and Golgi bodies in plant cells Golgi bodies are also called dictyosome Er(Ser and RER), ribosomes etc. But they have some differences as follows:

Organelles present in plant cells but not in animal cells Plastid, cell wall Organelles present in animal cells but not in plant cells Centrosome, Lysosome.

Do you know what is the cause of so beautiful colour of butterflies, aquarium fishes, colourful birds etc. It is not due to plastid. Then what is this colour? This is due to chromatophores.

Plant C And Its Distribution

Concept Of Tissue As An Organization Level within A Multicellular Living Body

The Cell Is The Structural And Functional Unit Of Life: Living organisms are either unicellular or multicellular. In unicellular organisms, the body consists of a single cell, which is capable of performing all the activities of life. In multicellular organisms, the body consists of more than one cell. Here the cells form different groups based on their common origin and specific functions.

Tissue Definition: A group of cells, similar or dissimilar in shape and of the same origin and performing particular functions in a multicellular living body is called tissue. The term tissue was given by Bichat.

Different Types of Plant Tissue

Plant Tissue: There Are two broad kinds of plant tissues, namely – Meristematic Tissue and Permanent Tissue

Meristematic Tissue

Meristematic Tissue Definition: A tissue comprising immature cells which are always in a state of division forming new cells is called meristematic tissue.

Characteristic features:

1. Cells are arranged compactly without intercellular spaces,
2. Cells filled up with dense cytoplasm,
3. Vacuoles if present are small and few,
4. The cell wall is thin, made up of cellulose and pectin
5. The nucleus is prominent and larger
6. Cells are always in a constant state of division.

Distribution: According to location i.e. distribution meristematic tissues are

Apical meristem: Present at the growing apex of root, stem and leaf. If apical meristem divides and grows, the plant increases in length known as primary growth.

Intercalary meristem-Present in between the permanent tissues.

Lateral meristem- Present at the lateral sides of roots and stems. If lateral meristem divides and grows, the plant increases in width and thickness, called secondary growth.

Can you state the reason?

What will happen by cutting a stem tip of a plant? You will observe no further growth in the length of the stem occurs, why?

Function:

1. Meristematic tissues help in the overall growth of plant organs from which other tissues develop.
2. What type of tissue is responsible for the growth in length of the stem and root?
3. What type of tissue is responsible for the increase in width of the stem and root?

Activity: Take two glass jars of the same size. Next, pour water into each jar. Now take two bulbs of onion more or less the same size and put one in each jar. The fibrous roots of the bulb in one jar i.e. jar No. lisas such, but the roots of the bulb on the second jar are trimmed with the help of a scissor. The roots of both bulbs are submerged in water. Observe the growth of roots of two onion bulbs note down your observation and mention the reasons behind it.

Permanent Tissue

Permanent Tissue Definition: The tissue in the plant body which have lost the power of division is called permanent tissue.

Characteristic Features :

1. Intercellular space may be present in between the cells
2. Cells may or may not contain protoplasm and, hence may be living or dead.
3. The cell wall is made up of cellulose and may be thin or thick
4. Cells are matured and have no power of division
5. Vacuoles are present.

Types Of Permanent Tissue: Permanent tissue is classified into two broad types, namely:

Simple tissue: Example Parenchyma, Collenchyma and Sclerenchyma and

Complex tissue: Example Xylem and Phloem.

Simple permanent Tissue :

Simple permanent Tissue Definition: Tissue consisting of only one type of cells (homogenous) forming uniform and mass performing the same function is called simple permanent tissue.

Types of simple tissue: According to the shape of the cell, there are three types such as parenchyma, collenchyma and sclerenchyma.

Parenchyma

Parenchyma Definition: Simple permanent tissue with thin-walled living cells are parenchyma.

Characteristic features: The living cells are oval to round in shape, thin-walled and with intercellular spaces.

• The cells contain central vacuole and starch granules in their cytoplasm.
• Cells contain abundant cytoplasm with a prominent nucleus. Parenchyma cells with chloroplasts are called chlorenchyma,
• which helps in photosynthesis and cells with abundant air cavities in between are called aerenchyma. Air cavities filled up with gases help the aquatic plants float.

Distribution: Parenchyma tissue forms the ground tissue of plants and occupies large portions of plant bodies. They are present in the cortex, pith, medullary rays, epidermis of roots and stems, mesophyll tissue of leaves, the pulp of fruits, embryos, the endosperm of seeds and Parenchyma. in the conducting tissues like the xylem and phloem.

Parenchyma  Functions :

1. Helps in manufacturing food by photosynthesis. Parenchyma contains chlorophyll is called chlorenchyma (as in leaf) whereas parenchyma containing air is called aerenchyma (as in lotus).
2. They function as storage tissue by storing starch (reserve food).
3. When associated with conducting tissues like the xylem and phloem, they help in the transportation of water and food matters. In turgid conditions, they provide support to delicate parts.

Collenchyma Definition: Simple permanent tissue walls whose cells are unevenly thickened by additional cellulose deposition, are called collenchyma. ,

Characteristic Features: The living cells are closely packed, and elongated in shape, with thickenings at their corners due to uneven deposition of cellulose. Cells have no intercellular spaces in between. The cells contain chloroplast and appear to be polygonal in cross-section.

Distribution: Collenchyma is present below the epidermis of dicot stems and also in the stalk of flowers pedicel and stalk of leaf, petiole, leaf blades.

Collenchyma Functions :

1. Provides mechanical support to plant organs.
2. Collenchyma cells containing chloroplastids can prepare food by photosynthesis.
3. The cells are responsible for providing flexibility and plasticity and also give strength to the plant parts.

Sclerenchyma Definition: Simplepermanenttissuewhose cells contain thick uniformly hard lignified walls, and are dead are called sclerenchyma.

Characteristic Features: The tissue comprises two types of cells—Sclerenchyma fibres and Sclereids or Stone cells.

Sclerenchyma fibres: Long, narrow cells with pointed ends, uniformly thickened lignified walls, and small openings (pits) are called sclerenchyma fibres. At maturity, the cells die due to loss of protoplast. Cross section of fibres shows angular cells e.g., fibres of hemp, flax, and jute are sclerenchyma fibres, fibres are present in the vascular tissues of root, stem and leaf. Cotton fibre is not sclerenchyma fibre but they are outgrowth a cross-section, of the epidermis of the seed coat.

Difference between Parenchyma and Collenchyma :

Difference between Collenchyma and Sclerenchyma :

Difference of Parenchyma, Collenchyma and Sclerenchyma :

Sclereids or Stone cells: Spherical, or oval cells with unevenly very thickened walls are called sclereids or stone cells. They are shorter in size with many pits on their walls. Walls of sclereids are hard and lignified, also called stone cells or grit cells.

Distribution: Sclerenchyma fibres are present in the hypodermis and the vascular tissues and sclereids are present in the fruit wall of guava, pears, etc. seed coats, and the bark of trees and leaves.

Sclereids or Stone cells Functions:

• Provides rigidity and strength to plant parts.
• The tissue also helps in withstanding stress and strains.

Things To Remember

1. The structural and functional unit of life is called ceil.
2. A complex of cells of common origin (Fahn, 1967) is called tissue.
3. One type of immature cells which possess the power of division is called meristematic tissue.
4. The type of meristem present at the apices of stems and roots of vascular plants is called apical meristem. ‘
5. Sclerenchyma is a dead simple tissue.
6. Parenchyma cells containing chlorophyll are called chlorenchyma.
7. The parenchyma containing the air cavity is called aerenchyma.

Complex Permanent tissue :

Complex Permanent Tissue Definition: Tissue made up of two or more cell (heterogeneous) types is called complex tissue.

Types of Complex Tissue: The Xylem and Phloem are the two types of complex tissues, also called conducting tissues or vascular tissues and together they form vascular bundles.

Xylem

Xylem Definition: The complex permanent tissue associated with the conduction of water and mineral salts in vascular plants is called the xylem.

Types: The Xylem is a complex tissue as it consists of different types of cells, both living and non-living, namely Tracheid, Trachea or Xylem vessels, Xylem parenchyma or Wood parenchyma and Xylem fibre or Wood fibre.

1. Tracheid: Elongated dead cells, tubular and with tapering end walls.
2. Trachea or Xylem vessels: Elongated dead cells, tubular but with no end walls and joined end to end forming a continuous pipe, are trachea or vessels. The cells are thick and lignified.
3. Xylem parenchyma or Wood parenchyma: The living parenchyma cells of xylem tissue are called xylem parenchyma or wood parenchyma. The cells may be thin or thick-walled. This is the only living tissue of xylem.
4. Xylem fibre or Wood, fibre: Thick-walled fibre like sclerenchyma fibres forming components of xylem tissue are xylem fibres or wood fibres.

Distribution: Xylem is present in the vascular bundles of higher plants.

Functions :

1. The xylem helps in the transportation of water and solutes unidirectionally called the ascent of sap.
2. Acts as supportive tissue, imparting mechanical strength to the plant body, (iii) Helps in the storage of water and mineral salts.
3. All xylem elements take part in the Conduction of water and mineral salts except one, can you ^ name that element?

Phloem

Phloem Definition: A phloem is complex permanent vascular tissue responsible for transporting food in a plant body.

Types: The components of the phloem are the Sieve tube, Companion cells, Phloem fibres or Bast fibres and Phloem parenchyma.

1. Sieve tube: Elongated tube-like living cells arranged in a row, with their perforated end walls forming a sieve. The cells are non-nucleated and their protoplasts are interconnected through sieve plates. They possess vacuolated cytoplasm. . .
2. Companion cell:  Elongated, lens-shaped cells containing dense cytoplasm and prominent. nuclei are companion cells. Cells maintain a connection with sieve cells through pits.
3. Phloem fibre or Bast fibre:  Elongated fibres like sclerenchymatous dead cells with thick walls containing pits and interlocked ends, are phloem fibres or bast fibres. Jute fibres are bast fibres.
4. Phloem parenchyma: Living thin-walled parenchyma cells associated with phloem are called phloem parenchyma.

Distribution: Phloem occurs in the vascular bundles of higher plants, forming conducting or vascular tissue.

Things to Remember:

• The xylem is a dead complex tissue.
• The only living component of the Xylem is the Xylem parenchyma.
• Pholem is a complex food-conducting system of vascular plants.
• Sieve tubes of phloem are living cells without nuclei.
• Jute fibre is the bast fibre of Phloem.

Functions :

1. Conduction of food by sieve tubes of phloem both in upward and downward directions
2. Storage of organic food matters,
3. Lateral translocation of food by the companion cells.

Know The Fact: Out of the four elements of phloem, only the sieve tubes have the power of bidirectional movement of food matters.

Activity:

The figure shows a transverse section of a sunflower stem. Observe the section and note down the different tissues composing every layer in a notebook. Then observe each type of tissue element present within the section

Difference between Xylem and Phloem :

Animal Tissue

The multicellular animal body is made up of many cells. In most cases, one type of cell is closely packed together and serves the same general function. All these cells form tissues.

Classification Of Animal Tissue:

Epithelial Tissue

Epithelial Tissue Definition: The tissue which acts as covering material over the internal (hollow organs) and external surfaces of the body is known as epithelial tissue.

Classification (Types) of Epithelial Tissue: Epithelial tissues are classified into two main divisions depending on the number of cell layers. These are (a) simple epithelial tissue and (b) stratified epithelial tissue.

• Simple epithelial tissues or Simple epithelium: The hardest epithelial tissue is the enamel of the tooth. Enamel is the hardest substance in the body. It is harder than bone.
• Simple epithelial tissue: Simple epithelial tissue is composed of a single layer of cells, present on a thin basement membrane (composed of loose connective tissue). Based on the shape of cells

Compound epithelial tissues or Stratified epithelium :

Stratified epithelium stratified epithelial tissue or compound epithelium is composed of many layers of cells. Depending on the shape of the constituting cells and structural arrangements this variety of tissue is sub-divided into the following types

1. Stratified squamous cornified: Found in the skin and helps to protect from injury (Cornified means layers of epithelial tissue to form a horny structure).
2. Stratified squamous nom cornified: Found in the cornea, mouth, pharynx, etc. and helps to afford mechanical protection.
3. Stratified cubical: Found in the pharynx, epiglottis etc.
4. Stratified columnar ciliated: Found in the soft palate, some stratified cubical epithelium parts of the larynx, etc.

Do you know that the horn of the Rhinoceros is a bunch of modified highly keratinised hair? The spine on the body of a Porcupine is modified hair.

Connective Tissue

Connective Tissue Definition: The tissue which serves the important function of connecting the various tissues and organs of the body or supporting the functionally active structures is known as connective tissue.

Classification ( Types) of Connective Tissue :

Muscular Tissue

Types of Muscular Tissue:

• So, Striated muscle or skeletal muscle is voluntary
• Unstriated muscle or smooth muscle is involuntary.

Do you know ‘titin’ protein in muscle is the largest known protein in animals

Nervous Tissue

Do you know, that neurons can not divide after birth? Then, how does the brain grow with increasing age?

Do you know what is the chemical nature of Nissl’s granules in neurons?

In the cyton of neuron RER (Rough Endoplasmic Reticulum), a cluster of ribosomes forms granular substances called Nissl’s granules.

Major Organs Of The Human Body And Their Function

Major Organs Definition: A distinct and differentiated part of the body of an organism, formed of one or more types of tissues, that performs one or more specialized functions is called an organ. Some common examples of organs in the human body are the eye, ear, lungs, heart etc. The human body is formed of all four types of animal tissue epithelial, connective, muscular and neural.

Thus the sequence of aggregation in the body of a multicellular animal (Example: human) may be as follows:

The Positions of Different Organs in Man and Two Major Functions of Each Organ :

Life And Its Diversity

Basic Properties Of Life

All activities of the living body are the result of the constant conversion of tr stored energy of the body (that stays at rest) into the kinetic one (i.e., the workable energy for the dynamic form).

• These activities are known as the characteristics of fife.
• Life is an energy-enriched substance that requires energy through the activities of a complex biochemical substance known as protoplasm
• which is provided with a system of self-equilibrium and helps the individual to adapt to the constantly changing environment to maintain a steady state.
• The term ‘Biology’ was first proposed by Lamarck and Treviranic

Life Can We Define It

Aristotle (384 – 322 B.C.), the great Greek philosopher, was the first to recognize pierce arc animals as living objects, but he failed to find a precise definition for life.

• The vital force that keeps the organism living, is life.
• It probably has no synonym. Life is abstract.
• Life is inseparable from the organism itself and fails to exist outside the living body.
• Hence, it is futile to attempt to define life.
• How life has come into existence on this earth
• What was the nature and characteristic of life at the time of its origin?

Read and Learn More Class 9 Life Science

The human mind has variously argued to find out the answer, since the inception of its civilization.

• Still, since Aristotle none has been able to try to give a precise definition of life.
• But, we all know that the activity of life is the expression of life and that is why we often use the term ‘lively’ to denote its activity. Aristotle is known as the ‘Father of Biology’.

Life is embodied in living organisms. It is often compared with the flame of a burning candle. The energy for such burning remains stored in the candle itself.

• The chemical phenomenon of burning or oxidation involves a rise in temperature in the surrounding medium.
• Heated particles are dispersed into violent vibrations which are manifested in the form of a flame that emits heat and light energies.
• Here, the flame is inseparable from the candle itself, since it persists only as long as the burning of the candle continues. Similarly, life persists only so long as the various lively activities of the organism continue. Again, the flame is extinguished when the candle-substance supplying energy to it is exhausted.
• Normally, life also ceases to exist when the stored energy of the living body is gradually spent up and not renewed. Hence, life and lively activities demand a continuous expenditure of energy like the constant expenditure of heat and light energies of the candle-substance to keep the flame ablaze. It is this energy that affords the power to work.
• It has two states of existence potential the stored energy that stays at rest, and kinetic, the other form is the workable energy for the dynamic form. Life, as such, involves a ceaseless conversion of the potential to kinetic form. Life shows some basic properties that are absent in non-living objects.
• Life shows the capacity to reproduce itself and can produce new life, they have the power to uptake and use energy can perform metabolism. They can also respond to external stimuli. Life is defined as the state of being alive manifested by growth, reproduction, and endowed with evolutionary potential.

Explanation of the basic properties of life with example

The characteristics of living organisms are the criteria of life. Some basic properties of life are cited below with examples.

1. Definite Form and Size: The shape of every living organism is definite (apart from a few exceptions example Amoeba). They maintain normal forms and activities irrespective of the changing environment.

2. Movement and Locomotion: Movement, concerned with protoplasmic movement only (in the case of unicellular organisms) and movement of different parts or organs of the body (in the case of multicellular organisms) are characteristic of living organisms. Protoplasmic movement is observed in Paramoecium (animal) and water-weed Vallisneria (plant).

• Observe the protoplasmic movement by taking a living Vallisneria leaf under a microscope note your observation and write down what you have observed.
• In higher animals definite and effective locomotory organs are present, such as fins of fishes, limbs of tetrapods, wings of birds, etc.
• while in unicellular animals pseudopodia (Amoeba), cilia (Paramoecium), and flagella (Euglena) are locomotory organelles that serve the purpose of locomotion.

3. Metabolism Definition: The total of the biochemical changes involved in a two-fold process of waste and repair of the protoplasm is known as metabolism.

• The constructive anabolic phase is the one in which complex substances are formed and the destructive, catabolic phase is the one where substances are broken down and discharged.
• These processes occur constantly within the protoplasm of living organisms, where uptake and use of energy occur.

• The constructive (repair) phase is one in which food materials are built up into more complex substances and the process is known as anabolism, (GK, Ana = upper, balls = throw), while the other phase (waste) is destructive, and is known as catabolism [cata = below, balls = throw).
• For instance, photosynthesis is an anabolic process in which sugar is formed in the cell and potential energy is captivated within the sugar molecule. Respiration is a catabolic process in which the captivated potential energy is released from the sugar molecule as kinetic energy with the oxidation of the sugar molecule.

4. Nutrition: The process of absorption of soluble food and its assimilation into protoplasmic substance, through many successive processes like ingestion, digestion, absorption, assimilation, and egestion is called nutrition which is a characteristic of living organisms.

5. Secretion: Enzymes and. hormones are two important secretory products taking part, in biological reactions influencing the overall metabolic activities of living organisms.

6. Transportation (Circulation): The living body has an organized seif-distribution system using which various substances are transported from one part to the other part of the body. In plants the transportable medium is water and in the case of animals, the transportation medium is water (lower animals example Hydra) and blood (higher animals).

7. Excretion: As a result of continuous metabolic processes going on in the protoplasm, various types of excretory products are produced which are mostly harmful to the body; these are commonly known as excretory products.

• These products are formed during the oxidation of organic food substances, hence, it is a catabolic process.
• Apart from carbon dioxide, these products are mostly nitrogenous substances, namely, Ammonia, Urea, and Uric acid.
• The process by which an organism is relieved of harmful excretory products is known as excretion.

8. Irritability: The capacity to respond through internal changes to various exciting agents is commonly known as irritability. The changed environmental condition that excites and responds to the living organism is known as the stimulus, during which a living body reacts called a response.

• Thus the ability of the living body to respond to stimulus is known as irritability.
• The snail or any such animal, if disturbed by touch, usually withdraws its body within the shell.
• Here, the touch acts as a mechanical stimulus, and the withdrawal of the body is the manifestation of irritability.
• The sensitive plant Mimosa pudica (B. Lajjabati), when touched, closes the leaflets.
• In both cases, the organisms protect themselves from their enemies.
• The sunflower shows a movement of the flower cluster towards the sun which is a response towards the stimulus of light.

9. Reproduction: A living organism is capable of reproducing its kind.

• Thus, the mechanism of handing over life activities to new individuals from preceding ones is ordinarily called reproduction
• However, whatever the method of reproduction, the offspring resembles the parents when they attain maturity and gain a new life.

10. Heredity: The transference of characters from parents to offspring is called heredity which forms a characteristic of living organisms*.

11. Rhythmicity: Functional rhythm forms a basic property of protoplasm. All vital activities of living organisms follow a rhythmic sequence.

12. Life Cycle, senescence, and Death: The living organism is mortal with a variable limited life span.

The individual appears with birth from pre-existing living forms and grows, then attains maturity, reproduces offspring, gradually ages, and finally attains death.

A Brief Outline Of The Abiotic Origin Of Life Prebiotic Conditions

A brief outline of the abiotic origin of life on Earth:

Origin Of Life On Earth Definition: The process of gradual development of life from inanimate objects (non-living matter) spontaneously is called the origin of life. After the initial vibration of life, the simple form of organisms gradually becomes complex over time the process is known as organic evolution.

• Organic evolution is a slow but gradual progressive process where a simple form of the organism becomes complex over time through the process of reproduction, variation, and heredity.
• The whole concept of evolution can be summarised as “Omni Vivum Example Vivo” which signifies “All living forms have evolved from preexisting living forms”
• Various theories have been proposed to explain the origin of life on Earth of which theory of abiogenesis or chemical evolution is most acceptable. This theory can be explained in two ways. steps chemical evolution and biological evolution.

Chemical evolution (Chemogeny) Definition: The combination of different chemicals gradually to form organic polymers is called Chemical evolution.

1. The atomic phase: In the earliest history of Earth, there were numerous atoms of various elements like H, N, C, S, P, etc.

2. Formation of simple molecules: These free atoms combine to form simple molecules like H₂, N₂, CH₄, H₂O, NH₃, CO₂, etc. H₂ and O₂ combine to form H₂O (water r vapor)—thus all O₂ was exhausted. That’s why the atmosphere of primitive earth was free from O₂ and the atmosphere was reducing atmosphere.

3. Formation of simple organic molecules or monomers: Different early molecules combined to form simple organic molecules like simple sugars (glucose, ribose, deoxyribose, pentose, etc.), nitrogenous bases (purines, pyrimidines), amino acid, fatty acid, glycerol, etc.

4. Torrential rain: Gradually water vapor formed clouds from where rainfall started. This rainwater dissolved various molecules (organic and inorganic) that moved into rivers, seas, and oceans.

• For various chemical reactions, energy is needed which is probably electrical energy (during thundershower and lightening), high energy radiation, solar radiation (UV-ray, X-ray, etc.)
• Oparin and Haldane (1924) called this mixture of dissolved molecules in the water a ‘prebiotic soup’ or ‘hot dilute soup.

5. Formation of complex organic molecules or Macromolecules: Various organic monomers like amino acids, fatty acids, hydrocarbons, etc.

• polymerized (in the presence of different energy sources as mentioned above) to form macromolecular polymers.
• Thus amino acids could form protein, monosaccharides form polysaccharides, fatty acids,s, and glycerol form fat.
• Similarly, nucleotides polymerized to form nucleic acid. In this way, different organic constituents of protoplasm probably evolved.

Do you know that probably evolved earlier to DNA?

Oparin Haldane Theory :

Biological evolution (Biogeny) Definition: The aggregation of different organic polymers to form primitive living cells is called biological evolution. Very high temperatures in early earth resulted in many chemical combinations to form varieties of biomolecules that were aggregated differently to develop the first living cell.

Different steps of biological evolution can be explained as follows:

1. Protobiont or Protocell or Eobiont: A protocell is a self-organized assembly of a spherical collection of lipids (in an orderly manner) which is supposed to be a stepping stone to the origin of life. Protocell has been explained in two ways :

Coacervate (Oparin and Haldane, 1920): Coacervate was defined as spherical aggregates ’ of colloidal droplets held together by hydrophobic forces. They measured approximately 1-100 micrometers. They lack a. definite membrane.

For reference only: The term coacervate is derived from the Latin word 1Coacervare’ which means “to assemble or cluster.” Oparin postulated that a protocell consisted of carbohydrates, protein, lipid, and nucleic acid that were accumulated together to form coacervate. This aggregate was covered by a film of water molecules.

Microsphere or proteinoid microsphere (Sidney Fox, 1964): Microsphere can be defined as spherical bodies, a few micrometers in diameter, formed of a mixture of amino acid molecules.

• They are soluble in water. A microsphere is a collection of nonliving organic macromolecules with a layered outer boundary that was not formed of lipids.
• This hypothesis was proposed by Sidney Fox who explained that early protocell was probably a microsphere.
• Microsphere is a collection of nonliving organic macromolecules with double-layered nonlipid outer boundaries.
• However, microspheres exhibited some membrane-like characteristics. They could absorb material from the surrounding medium.
• They had the ability of motility, growth, budding, binary fission, and capacity of reproduction by budding and fragmentation.

Some Scientists claimed that microspheres could be considered the first living cells

2. Origin of first living prokaryotes: Prokaryotes originated from protocells about 3-5 billion years ago in seawater. The atmosphere was anaerobic since there was no free 02 in the atmosphere.

• Prokaryotes are surrounded by membranes and cell walls. In the cytosol, there was nucleic acid but no nuclear membrane.
• Cytosol contains a mixture of various inorganic and organic materials—monomers, polymers, etc.
• Eukaryotes evolved from prokaryotes 1-5 billion years ago. They had various membranous and nonmembranous organelles.
• The nucleus was bounded by a nuclear membrane. Further complexity continued in the course of evolution.

A summary of the main steps in the origin of life under the Modern idea about the Origin of life :

Sources Of Variations In Life

Variations are the differences noticed among the species on earth.

Variations are mainly of two types:

1. Hereditary,
2. Environmental.

1. Hereditary variation: The variations or specialties or new characteristics that are inherited from parents to offspring (progeny) by genes are called hereditary variations. Thus genetic variations are transmitted from one generation to the next. This genetic variation (mutation) is the raw material of evolution that may give rise to new species over time.
2. Environmental variation: Various special adaptive characteristics that develop in organisms in different environments are called environmental variations. These variations are generally temporary but sometimes may be inheritable.

During sexual reproduction, inheritable variations may be transmitted to the offspring. Thus more and more variation may develop generation after generation resulting in a diversity of life forms.

Biodiversity: The collection of diverse natural plants, animals, and microbes on earth L called biodiversity. There is an enormous variety of plants and animals on earth. Our earth ports more than one million species. This spectrum of biodiversity has been developed on earth over the last 3 billion years (300 crores years).

For reference only: Chart showing Geological Ages and Associated Organic Events or Evolutionary changes of plants and animals :

The chart shows the evolution of life:

Biology Is The Study Of Patterns And Processes Of Life And Its Diversity

We study Biology for the following objectives:

1. To awaken the pupil’s curiosity and interest in the plant, insect, and animal life around him in his environment. :
2. To form in the pupil’s habit of accurate observation and of testing knowledge by experiment.
3. To raise awareness in the pupils of the mutual interdependence of life forms in nature and.
   their relationship with the environment as a whole.
4. To give pupils an intelligent and appreciative insight into the working of the life processes in nature’s kingdom…
5. To kindle pupil’s love for animals (fauna) and plants (flora).
6. To develop in the pupils of upper forms a spirit of research to enrich human life.
7. To develop knowledge, information, and understanding about social problems which are essentially biological.
8. To develop secular, liberal, scientific, and reasoning minds among the students.
9. To develop the physical, mental, intellectual, and emotional aspects of the students in a balanced way.
10. To develop a sense of cooperation and understanding among the different people in different parts of the country and among different countries about the balanced ’ distribution of natural wealth and resources.
11. To develop understanding and awareness of pollution, conservation, and development of environmental resources. This is for sustainable development and to avoid wanton wastage of natural resources.
12. To develop ideas of unity among people, the right to judicious exploitation of natural resources.
13. To develop national integration and international understanding about Biodiversity, natural resources, and commonness about life processes and diversity in form and function thus promoting peace in the world perspective.
14. The overall knowledge about the living world, distribution of natural resources, and man’s position in nature would help to develop the sense of a good citizen of a democratic country.

Biology is the science of life. It is the study of life in the case of humans, in other forms of animals together with plants. We study biology to come up with an idea about the structures and activities of different plants and animals. Biology is a basic science that helps us to know about the different activities of living organisms. The subject is also related to the environment. It gives an idea about the origin of life and explains its gradual evolution to develop ultimately various types of new plants and animals gradually.

Biological Studies At Different Levels And Aspects

Different branches of Biology :

1. Biochemistry: Biochemistry (Biology and Chemistry)- It deals with the study of chemical substances and chemical processes of living things.
2. Molecular Biology: The study of the structure and function of large molecules associated with living organisms particularly—proteins and nucleic acid (DNA and RNA). Molecular genetics is a specialized branch, concerned with the analysis of genes
3. Immunology: The branch of science that deals with the responses of the body when challenged by antigen is referred to as immunology (immune = free) TEB
4. Genetics: Genetics deals with heredity and variation. It tries to explain the mechanism by which the offspring resembles its parents. It also explains variations in plants and animals.
5. Histology: Histology is the study of the microscopic structures that form the organ and their observations. This subject deals with the structures, functions, shapes, and sizes of cells and tissues of the living organism.
6. Anatomy: The branch of science that deals with internal structures and organs after dissection is called anatomy.
7. Physiology: It is the study of the different functions and activities that take place within the living organism. It deals with how the plant absorbs water by its roots and indicates the precise mechanism through which it is conducted to the different organs and finally to the leaves. Similarly, it deals with the functions of different organs in an animal body.
8. Ecology: According to scientist Phillipson (1970) the branch of science that deals with the interrelationship between organism and surrounding environment is called ecology. German biologist E. Haeckel (1869) first proposed the term ‘ecology’, which is derived from the Greek word “Oikos” meaning “dwelling place or house” and “logos” meaning study. The term ecosystem was proposed by Tansley. The ecosystem is the unit of ecology.
9. Behavioral biology: How someone or something behaves in the environment comes under behavioral study i.e. the sum of the responses of an organism to internal or external stimuli. Behavior is the change in activity of an organism in response to a stimulus. Behavioural biology (ethology), is the study of the biological and evolutionary bases for such changes.

Pavlov’s Experiment: Pavlovi used to give some food to a dog. Usually, the dog salivated to eat the food. He sounded a bell which had nothing to do in salivation.

• However, the continued association of the bell with the food caused salivation not only in response to the food but also to the sound of the bell.
• So later on, when only the bell is rung, without giving food, the dog salivates.
• This shows that the reflex of salivation is acquired by the dog as a result of repeated training. This is an example of conditioned reflex.

Behavior of honeybee : (Honeybee is a social insect) Worker bees flap their wings to cool a bee hive and huddle together to warm a bee hive.

• They can maintain a constant temperature in the bee hive. Forager bees can locate foraging grounds and communicate about the location with their colony mates through round dance and waggle dance.
• Workers showing helping behavior between members is called altruism meaning self-sacrifice.
• There are three types of honey bees Queen (fertile female), Worker (sterile female), and drones (fertile male).

10. Evolution: Organic evolution means a gradual progressive but dynamic process where a simple form of organism gradually becomes complex with time by the process of reproduction, accompanied by variation and heredity. For example, the evolution of vertebrates can be explained :

Other branches of biology :

1. Palaeontology: (Palaeos = primitive; ont = existence; logos = discourse). This is the brand) of science that deals with the study of fossils. The present-day distribution of plants and animals does not conform to their ancient distribution. The extinct plants and animals of prehistoric ages when preserved under different geological strata are called fossils.
2. Economic Biology: This branch of Biology deals with the economic or utilitarian aspect of the subject. Examples: Peorlculture with pearl oysters, Apiculture with honey bees, Sericulture with silkworms, Pisciculture with fishes, Poultry birds, Dairy animals, crops, etc.
3. Cytology: This deals with the study of cells.
4. Microbiology: It is the study of organisms that are too small i.e. an object which have a diameter of less than 0-1 mm. They can be studied only under a microscope. Microorganisms include some metazoan animals, protozoans, many algae, fungi, bacteria, and viruses.
5. Taxonomy: It is the study of the classification of plants and animals based on their relationship, resemblances, and differences. The apparent dissimilarity between two organisms does not rule out the possibility of their actual basic closer relationship (for example caterpillar and butterfly). On the other hand, the apparent similarity between two organisms does not necessarily signify their actual kinship (for example bird and bat).
6. Pathology: Pathology deals with the nature, symptoms, and causes (pathogens) of different diseases in plants and animals. It tries to point out their prevention and remedies.
7. Major divisions of Biology :
8. Botany (Botane – Herbs) and Zoology (Zoon = Animal) are the major sister branches of Biology.
9. Botany: Botany deals with the plant world. It is further sub-divided into Bacteriology (bacterium – a little rod) which deals with the study of microbes (bacteria); Agrostology, dealing with the study of grass and the like; Dendrology, dealing with the trees; Mycology, dealing with the Fungi; Palaeobotany dealing with the plant fossils, etc.
10. Zoology: Zoology deals with the animals. It has also many sub-divisions, namely, Protozoology, dealing with unicellular animals; Helminthology, dealing with parasitic worms; Entomology, (entomon = an insect) dealing with insects Malacology, dealing with mollusks; Ornithology, dealing with the waves.
    • Further, Palaeontology deals with animal fossils; Fisheries, in a broader sense is concerned with the exploitation of the water resources of animals, etc.
    • Likewise, Anthropology (anthropoids = a man) is concerned with the study of various races of mankind. Biogeography deals with the geographical distribution of plants and animals on Earth.

Infusions Of Knowledge From Other Branches Of Science Into Biology

No branch of science is independent. The various facts and the variety of knowledge drawn from every branch of science nourish each other branch to develop. Fundamentally Biology is a vast division of science that is concerned with the entire organic world and tries to seek the relation between the inorganic and living things. In its endeavor, it requires various knowledge of the Physical sciences of physics, chemistry, and mathematics (including statistics).

For an intimate understanding of the fundamental life processes Biology has combined with various branches of science to form the following new subjects:

1. Bio-Physics (Biology+Physics): It is Concerned With the application of physics to the study m), EEG (Electroencephalogram), MRI (Magnetic Resonance Imaging), CT Scan (Computerised Tomography), USG (Ultrasonography), etc.
2. Bio-Chemistry (Biology + Chemistry): It is concerned with the application of chemistry to the study of living things.
3. Bio-Mathematics (Biology+Mathematics): It is concerned with the application of mathematics to the study of living things.
4. Biometry (Biology + Statistics): It is particularly concerned with the statistical study of related organisms, e.g. statistics of variations.
5. Bioinformatics:  An important aspect of Biological Sciences is the Intugmtlon of Biology with tho Inloi million technology computers to form a subject culled blolnlonnnlliv,
6. Bio-geography (Biology + Geography): I bis division Is Concerned With studying the global dKtilhutloo of plants and animals.
7. Bionics(Biology + Electronics) deals with the study of molecular phenomena revealed within the parameters of electronics.
8. Paleontology (Biology I Geology): It deals with the study of fossils and is sub-divided Into two parts inilucoboUwy (dealing with plant fossils) and the other, paleozoology [dealing with animal loss), Do I still give in? Impression of the hard part of the body.
9. Marine Biology (Biology + Ocenogiaphy): It deals with the flora (Plants) and fauna (Animals) of the coastal area and the application of methods to check erosion of the soil and maintain proper ecological balance.
10. Space Biology (Biology + Space Science) Or Exobiology: It deals with the condition of living objects in space under various experimental treatments.
11. Cytogenetics (Biology + Genetics): It deals with integrating the methods and findings of cytology and genetics.
12. Cybernetics (Biology + Technology): It deals with the application of various technological devices for biological systems.
13. Biomedical Engineering: Biomedical Engineering is a branch of science that deals with the designing of different medical instruments and information providing knowledge about their production. Knowledge of this technology is used in the production of artificial limbs, implants, artificial heart valves, etc.

The emergence of new branches of Biology: Biology has enormous applications in other branches of science. It forms an important part of

1. Veterinary science: It deals with the treatment and surgery of animals.
2. Marine biology: It deals with the study of life in the sea.
3. Horticulture: It deals with the science of growing flowers, fruits, vegetables, and ornamental plants.
4. Sericulture: It is the technique of producing silk by rearing silkworms. Silk is made of two types of protein Outer layer Sericin and inner layer Fibroin.
5. Pisciculture: It deals with the technique of growing fish. Aquaculture→Fishery → Pisciculture. Aquaculture means the culture of all aquatic beneficial plants and animals. Fishery means a culture of beneficial aquatic animals (both fish and non-fish) only like prawns, crabs, fish, pearl oysters, dolphins, whales, etc. Pisciculture means a culture of fish only.
6. Cloning: It is the rapidly advancing branch of biotechnology introducing a body cell for producing an individual.
7. Molecular biology: It is the science that deals with interpreting biological events in terms of the molecules in the cell.
8. Biotechnology: it deals with the application of technology in biological processes such as biogas production from organic wastes—(for example Gobar gas plant); and the production of insulin through bacteria.
9.  Nuclear biology: It is the study effects of radioactivity on living things, for example, the Radiation of gamma rays in cancer patients.

Applications Of Modern Biology

Biology is the study of living organisms considering all aspects of the structure and function of organs, behaviour, and all life processes, that are found to occur.

• The advent of biological science started with the discovery of a microscope which allowed detailed observation of cells and cell organelles.
• The study of cell and cell components at the molecular level is very much essential to understanding the underlying mechanism of their function.
• Ultramicroscopy or electron microscopy provides visualization of the detailed structure of ceil and its components at the molecular level.
• The mechanism of all cellular phenomena should be studied at the molecular level to understand the actual mechanism underlying these processes.

1. Application of Biology in Agriculture: It is a form of applied biology. Agriculture in reality is largely the result of man’s taking advantage of the inter-relations of soil, climate, and natural inhabitants to select those particular combinations that meet his requirements. It deals with the raising of crops and livestock.

• In the production and protection of food and its improvement: Better varieties of crop plants such as rice, wheat, jute, sugarcane, pulses, and cotton are new experimental breeds. Disease-resistant grains are raised and seeds are vernalized by special treatment to yield the crop before the usual time of harvesting. Soil is saved from exhaustion by crop rotation. Plant diseases are cured by using preventive measures.
• Hybridization techniques: Hybridization techniques and modern methods of cultivation are being used for the production of new varieties of economically important plants like HYV (High Yielding Varieties) of plants, dairy animals, and poultry birds; use of disease-resistant varieties to increase crop production.
• Example: Paddy—IR8, Taichung, etc.; Wheat—Kalyansona; Poultry bird—Leghorn, Rhode Island Diary animals Jersy cow.

2. Application of Biology in Medicine: Discovery of antibiotics like Penicillin, Streptomycin, and Cloromycetin has helped to combat many life-threatening diseases.

• Penicillin is used to cure pneumonia and some other diseases.
• Insulin and human growth hormone are produced from genetically engineered bacteria with recombined DNA and are useful for the treatment of diabetes Mellitus and dwarfism respectively.
• The practice of vaccination is also an outcome of biological knowledge.
• Some medicines are prepared from inorganic products but the science of Ayurveda utilizing vast natural resources for the treatment of several diseases is an outcome of biological knowledge. Vaccination and inoculations are done to prevent diseases of many kinds.

3. Application of Biology in Space Science: The role of biology has become important in space research. The green algae Chlorella was kept in a spaceship to provide a constant supply of oxygen to the cosmonauts. The dried Chlorella is also consumed as food.

4. Application of Biology in other fields :

• Genetic engineering or biotechnology has a lot of applications like the synthesis of insulin and somatotrophic hormone) and various other useful biomolecules.
• Hybridization technique helps to produce varieties of HYV plants and animals, disease
  resistant plants.
• Use of bacteria for the treatment of sewage and domestic wastes; production of biogas (Gobar gas plant) as an alternative source of energy.
• Gene cloning, and tissue culture techniques have a lot of applications.
• DNA fingerprinting technique is extremely useful in forensic research.
• So many other important modern biological techniques that have tremendous applications in our lives are—Gene therapy, Genetic counseling, amniocentesis, production of monoclonal antibodies, and so on.

Classification Of Diversity Of Life Taxonomy

Earth is full of millions of different kinds of organisms at present and many millions more existed in the past and became extinct. The number of species living on earth comprises its overall biodiversity that changes over time as a result of both adaptive radiation and extinction. Biodiversity is the result of 3-5 billion years of evolution.

• Diversity characterizes most living organisms. There is an enormous variety of plants and animals on the Earth, and the high degree of species richness in tropical forests and coral reefs is a matter of marvel.
• Our Earth supports 10-30 million species of plants and animals. The diversity is due to the result of the continuous process of evolution extending over 3 billion years.
• The variety of life on earth that includes all species of plants, animals, and microbes along with the ecosystems within which they live and interact are together known as biodiversity.
• “Taxonomy is a science which includes identification, nomenclature and classification object; and is usually restricted to objects of biological origin”

Why organisms are classified: Various living organisms in this biosphere exhibit great diversity in shape, size, and form. The study of every individual separately is impossible. So, diverse forms of living organisms are classified orderly for ‘group study’.

A Very Brief History Regarding The Birth Of Modern Taxonomy Till Linnaeus

• Development of modern taxonomy in Europe when naturalists started encountering a high diversity of new living organisms, especially from the tropics—
• In the above pretext a very brief history regarding the birth of modern taxonomy till Carolus Linnaeus is stated below—

Based on habit characteristics the grouping of plants into herbs, undershrubs, shrubs, and trees was done by the Greek naturalist Theophrastus (370-285 B.C.). He was a student of Aristotle a Greek Philosopher and was known as the “Father of Botany”. Before the start of the Christian era, a compilation work done by Paraso in Vrikshayurveda is considered one of the earliest works done by an Indian, which deals with plants in a very scientific way.

His system of classification was based mainly on comparative morphology. Charaka considered the father of Ayurveda, described 200 kinds of animals and 340 kinds of plants, which was published in his outstanding book ‘Charak Samhita’. Similarly, Susruta was a famous surgeon.in ancient India.

For reference only: Jolm Ray (1628-1705), was an English philosopher, whose classification was based on an unusual mixture of old and new.

• He retained the method of earliest grouping of plants into herbs, shrubs, and trees as the principal division.
• He introduced the ‘key’ method of classification. He recognized monocots and dicots within the above groups.
• Further, he divided these taxa considering the characters of fruit and still further subdivided them based on leaf and flower characters,  Ray’s system of classification was based on the form and overall morphological structures of different plants.
• The major groups are

Herbal (herbs)

• Imperfect (plants without flowers) Cryptogams
• Perfectae (plants with flowers Phanerogams)

Dicotyledons (Seeds with two cotyledons) and Monocotyledons (Seeds with one cotyledon)

Arborae (includes trees and shrubs)

• Dicotyledones
• Monocotyledones

The term species was first introduced by John Ray. He described various kinds of plant species collected from all over Europe. The famous Swedish naturalist Carolus Linnaeus (1707-1778) classified plants and animals, which though artificial, is considered the father of modern classification. He first introduced the scientific system of naming of plants and animals, a method known as binomial nomenclature.

For reference only: Linnaeus plant classification is based on sexual reproductive organs like, the number of stamens and carpels, etc.

1. So, his system of classification is also called sexual classification. He divided: the plant kingdom into 24 classes of which the first class is Monandria and the last class is Cryptogamia.
2. Linnaeus divided the animal kingdom into six. classes, like :

• Mammalia,
•  Aves,
• Amphibia,
• Pisces,
• Insecta,
•  Virus.

Carolus Linnaeus recorded about 5900 species of plants in his published book ‘Species Plantarum’ (1753) and nearly 4200 species of animals in his, ‘Systema Naturae (1758). Linnaeus is known as the ‘Father of Taxonomy’. The term ‘taxonomy’ was first proposed by Candolle. In animals, instead of division, the term ‘Phylum’ is used.

Taxonomy And Taxonomic Hierarchical Arrangement Of Classified Groups

The hierarchy is the systematic framework of classification formed by the arrangement of taxonomic groups in a definite order starting from the higher category to the lower category.
In a classification of plants, the categories are Kingdom, Division, Class, Order, Family, Genus, and Species.

• The lowest category is species and the highest category is the Kingdom. Since the time of Linnaeus, the first taxonomist who established a definite hierarchy, the number of known animals (species) has increased enormously.
• Thus, the original basic categories have been split and additional ones have been accommodated among them.
• In the process, several subgroups have been established by combining the prefixes super or sub- with the original category names; for example, order and super-order, family, and sub-family may be mentioned.
• Further, a new category has been imposed between genus and family known as tribe and between order and class, known as cohort, while below sub-class and sub-orders infra-class and infra-orders respectively are used.

Steps Of Linnaeus’s Hierarchy

Any particular level in hierarchy classification is called a taxon (PI. Taxa).

1. species is a group of individuals exhibiting similar morphological character that breeds to produce their kind. It is the lowest step in hierarchy classification.
2. Genus: It is the term given to a group of closely related species.
3. Family: It represents a group of genera that show more similarity to each other.
4. Order: It represents a group of families showing resemblances in only a few characters.
5. Class: It represents organisms of related orders.
6. Division (Phylum): The Kingdom is divided into divisions until plants are placed in the final taxon the plant kingdom and into phylum in cases of Animal Kingdom.
7. Kingdom:  It is the highest category of classification including all organisms which share marked common characters. All plants are placed under the Plant Kingdom.

For reference only Examples: The Taxonomic categories of ‘Mango’ and ‘Man’ are stated below :

Binomial Nomenclature

Nomenclature may be defined as a system for assigning names to organisms. The Binomial system of Nomenclature was introduced by Swedish Biologist Carolus Linnaeus in the first edition of his “Species Plantarum” in 1753.

• According to this system, the scientific name of any species consists of two Latin or Latinized words. The term binomial means, L. ‘bi’ means ‘two’, and means ‘name’.
• The first name is the name of the genus, i.e., generic name and the second name is the name of the species, specific epithet.
• For example, the botanical name of paddy is Oryzo sotiva. The first word ‘Oryza’ is the name of the genus and the second word ‘Sativa’ is the name of the species of this genus.

Rules of Nomenclature: The following conventions of nomenclature may be noteworthy :

1. Names given to plants or animals before the publication of ‘ Systema Nature (10th edition) are not acceptable.
2. Names should be written in Latin or its derivative.
3. Both the generic and specific names (epithet) must be written in Italics, the genus
   starts with a capital letter and the species begins with a small letter, for example, Solanum tuberosum (Potato).
4. The specific name is usually a descriptive one, for example, Hygrophilia spinosa a plant with
5. Only a single valid name for each kind of organism is permitted. When two or more names are given correctly to a plant or animal, then the name used by the first author (the author who described the plant or animal first) is approved and the others would be treated as synonyms. This is known as the Law of Priority.
6. Scientific names must have a significant meaning which is the most salient feature of the organism.
7. The name of the author who first described a species is also added to an abbreviated form after the name of the species for example, Mangifero indica Linn, Here Linn refers to the author Linnaeus who first described the species.
8. In the case of animals, the suffix-effixes must be added to the family name and the suffix-effixes to the sub-family name.

For reference only: A list containing the names of certain plants and animals is given below

1. National flower of India (Lotus): Nelumbo nuclear
2. National fruit of India (Mango): Manglfera indict
3. The national bird of India (Peacock): Pavo status
4. National animal of India (Tiger): Panthcra tigres

Classification system up to Five Kingdoms of Life:

Five Kingdoms of Life

The most accepted one is the Five Kingdom System as proposed by R. Whittaker (1969).

• Various experts at different times classified all the living organisms under the kingdom, the largest taxonomic hierarchy virus
• containing only DNA or RNA as genetic material is not included under any scheme of classification.
• They do not possess cell walls and are without cytoplasm.
• They can perform reproduction only by invading the living cells.

For reference only :

• A monerian is Mycoplasma. They do not possess rigid cell walls.
• They are the smallest living organisms with a diameter of 0-1 MB
• Through the bacterial filter, they can be filterable, easily, which signifies their similarity with the virus.
• They can change their shape and size (exhibiting polymorphism) concerning variations in conditions of the environment a phenomenon termed as pleomorphism.

The five Kingdoms of life were

1. Monera: This includes prokaryotic, autotrophic, and heterotrophic living organisms.
2. Protista: This includes eukaryotic, unicellular, and both autotrophic and heterotrophic organisms.
3. Fungi: This includes eukaryotic, multicellular both autotrophic and heterotrophic organisms which show sporulation and absorptive mode of nutrition.
4. Plantae: This includes multicellular plants that have the power of photosynthesis, they develop on land or water.
5. Animalia: This includes multicellular eukaryotes with ingestive or holozoic mode of nutrition (five phases—ingestion, digestion, absorption, assimilation, egestion).
6. This kingdom includes all the motile and sessile animals.

Three Salient Features Of Each Kingdom

For reference only: Margulis and Schwartz in the year 1982, revised the five-kingdom classification as proposed by I R. Whittaker into one prokaryotic kingdom (Prokaryotae) and four eukaryotic kingdoms.

• The former includes Prokaryotae (Kingdom 1 Monera) and the latter includes four eukaryotic kingdoms (Eukaryotae) Protoctista, Fungi, Plantae, and Animalia.
• The collection of the diverse nature of plants, animals, and microbes on the earth’s surface is called diversity.
• The word Bio-diversity was first coined by Walter Rosen in 1986.
• In India, it is estimated that 45,000 spp. of plants occur including 18,000 spp. of vascular plants. Among animals, there are 50,000 spp. of insects, 4,000 mollusks, 6,500 other invertebrates, 2000 fish, 140 amphibians, 420 reptiles, 1200 binds, and 340 animals. The current loss of species diversity and the reduction in genetic variety of crops and wild spp. could seriously affect human welfare.

For reference only:

Facts to know: Biodiversity is a term given to the diversity of life forms found in a specific area.

Major groups of plant kingdoms: Algae, Bryophyta, Pteridophyta, Gymnosperm, and Angiosperm (Monocotyledon and Dicotyledon).

Classification of Kingdom Plantae

Nowadays in many cases plants. the kingdom is classified considering the major groups :

The Plant Kingdom is mainly divided into the following two groups: Cryptogams and Phanerogams.

Non-flowering plants or [Cryptogams] Definition: These plants do not bear flowers, hence no formation of fruits and seeds, and are termed as Nonflowering plants or Cryptogams. The word Cryptogam is derived from two Greek words, for example, Kryptos Concealed, and games = marriage. Non-flowering plants are divided into three classes

Thallophyta:

• The plants included under very simple.
• Their body is not differentiated “ into root, stem, and leaves.
• Their body is composed of a mass of cells called haikus. Hence, they are termed as thallophytic plants. Plants under Thallophyta are again divided into two groups
  • Example Algae and Fungi.

Algae :

• As their body cells contain chlorophyll, hence they can prepare their food.
• They are present in moist swampy places, ponds, jheels, etc.
  • Examples—Spirogyra (filamentous), Chlamydomonas (unicellular), Volvox (colonial), Chara (green algae) Fucus, Laminaria [brown algae); Polysiphonia (red alga) etc.

Fungi :

• They do not bear chlorophyll, so are colourless
• The plant body is made up of filaments called hyphae (sing, hypha).
• Hyphae collectively form mycelium,
• They are mainly parasites and saprophytes,
• They occur in rotten bread, fruits, leather, jam, jelly, cow dung, etc.
• Their cell wall contains chitin (Nitrogenous polysaccharide).
  • Examples— Mucor, Rhizopus, Penicillium, Saccharomyces (commonly called Yeast), Agaricus (Mushroom), and Helminthosporium. etc.

Difference between Algae and Fungi:

In the 5 Kingdom classification Fungi are placed in separate kingdoms (third Kingdom): BryophyCa (Ct Bryon, moss; faction, plant):

1. The adult plant body is a haploid gametophyte.  The plant body is either. thallus-like or differentiated into root-like (Rhizoid), stem-like (Cauloid), and leaf-like (Phylloid).
2. No true root stem or leaf is present,
3. The plant tissues contain chlorophyll and thus are capable of preparing their food,
4. They do not possess conducting channels in vascular tissues,
5. They usually occur in moist swampy places, for example, Riccia, Marchantia, Notothylas, Pogonatum, Polytrichum, etc.

Curious Facts:

1. Among all the existing living organisms in our world, the total diversity is much more in the case of animals than in plants.
2. The peat moss Sphagnum is called cotton moss because, in the Second World War, they were used as a substitute for cotton.

Pteridophyta (Gr. Pteris, feather, phyton, plant):

1. Adult plant body K diploid -.porophyu.
2. Plants under this division are differentiated into true roots, stern, and leaves.
3. Due to the presence of well-organized vascular tissues (xylem and phloem) and the absence of flowers, these plants are also called vascular cryptogams,
4. These are chlorophyll-containing plants so are capable of preparing their food,
5. They occur in moist swampy or wet places, In the history of plant evolution, vascular bundles first evolved in Pteridophytes.

• • Examples—Lycopodium, Selaginella, Dryopterls, Marsileo.

Difference between Bryophyta and Pteridophyta :

Flowering plants or Phanerogams Definition: Those plants whose body is composed of roots, stems, and leaves and produce fruits and seeds are called flowering plants or Phanerogams. (Gr Phoneros, visible well-organized vascular system.

Flowering plants are divided into the following two groups;

Examples:

1. Gymnosperms and
2. Angiosperms

Gymnosperms (Gr. Gymnos, naked, sperma, seed): The seeds of these plants remain exposed (naked), not covered using fruit. For that reason, they are termed as naked seeded plants, for example, Cycas, Pinus, and Gnetum.

Angiosperms (Gr. Angios, covered; Sperma, seed): The seeds of these plants remain covered using fruits. For that reason, they are termed closed-seeded plants, for example, Mango, Peas, and Wheat.

Difference between Angiospefms and Gypinosperms

Angiospermic plants are divided into two groups, for example, Dicotyledonous and Monocotyledonous.

• Dicotyledonous (Gr. Di, two; cotyledon, seed leaves): Seeds possess two cotyledons (Seed leaves).
  • Examples— Mongifero (Mango), Cicer (Gram), Pisum (Pea), Helianthus (Sunflower), Cucurbita, (Gourd), etc.
• Monocotyledonous (Gr. Mono, single; cotyledon, seed leaves): Seeds possess only one
  cotyledon (Seed leaf).
  • Examples— Oryzo (Paddy), Triticum (Wheat), Cocos (Coconut), Musa (Banana), Colocasia (Arum), Zingiber (Ginger), etc.

Morphological Comparison of Dicotyledons and Monocotyledons:

Classification Of Kingdom Animalia

How different animals are similar and different from each other Introduction: You have observed a great variety of animals living on earth.

• They are interdependent with one another and with the plant kingdom. Great varieties of animals comprise the biodiversity of the environment.
• Over a million species of animals have been described till now but they cannot be studied separately.
• Hence, the need for classification becomes very important.
• Based on similarities and dissimilarities of characteristic features, animals are classified into several groups.
• With the help of classification, an animal could be identified into a definite group, and its evolutionary position could be resolved.

Some useful terms related to animal classification Symmetry: The regular arrangement of body parts following a definite pattern is known as symmetry. The animals may be symmetrical (for example Sponges, etc.), bilaterally symmetrical (for example Insects, Fish, etc.), or radially symmetrical (for example Hydra, etc).

Diplobiastic and Triploblastic Organisation: In animals, during early embryonic development, if there are two layers in the embryo an external ectoderm and an internal endoderm, then the animals are called diploblastic example, Cnidaria. On the contrary, those animals having three embryonic germinal layers outer entoderm or middle mesoderm and inner endoderm are tailed as triploblastic animals’ for example, Platyhelminthes to Chordates (including man).

Development of organs Or systems from three germinal layers:

1. Ectoderm: Nervous system, the epidermis of the skin, enamel of the tooth, sweat gland, hair, nail, etc
2. Mesoderm: Connective tissue, muscle, bones, notochord, etc.
3. Endoderm: Inner linings of the digestive and respiratory tube, liver, pancreas, etc.

Coelom: It is the body cavity between an alimentary canal and body wall, which is surrounded on all sides both inwardly and outwardly by mesoderm. If the body cavity is not surrounded by mesoderm, it is called a pseudocolor ExamplesAschelminthes.

Segmentation: In some animals, the body is externally and internally divided into segments metamere-having “repetition of similar anatomical parts. This phenomenon is called segmentation metamerism Example: Earthworm.

Notochord: Some animals develop a mesodermally derived rod-like structure on the dorsal side of the body during embryonic development. This structure is called notochord and the animals with notochord are called chordates. Those who do not form notochord are called nonchordates example Porifera EchinodermS.

Broad Classification of Kingdom Animalia:

Phylum 1. Porifera (Gr. Porus = Poreferre = to bear) (Pore-bearing animals)

Notochord Salient features:

1. They are diploblastic, sedentary (sessile), aquatic animals.
2. The whole body is perforated by numerous pores called ostia.
3. Water flows through the body cavity called spongocoel which is lined by Choanocytes or Collar cells or flagellate ceil.
4. The whole system is called the canal system.

Notochord Examples: Neptune’s cup (Peterson sp.); Crown sponge (Scypha sp.)

Do you know? A particular porifera is commonly called a Venous flower basket”?

Can you identify the important functions of the canal system? ‘Sponges are multicellular animals without tissue formation” How do you justify it?

Phylum 2, CriidaHa’ (Gr. Khide = nettle or spine or sting). (Animals with, sling cells).

Canal System Salient features:

1. They are diploblastic animals having gastrovascular cavities.
2. The body consists of a cnidoblast cell that forms a stinging apparatus called nematocyst which is the organ of offense and defense.
3. The body of the animal may be Polyp (tubular body) or medusa (umbrella-shaped body).

Canal System Examples: Hydra (Hydra viridis); Jellyfish (Aurelia sp.).

Cnidaria (Physalia) is called ‘Portuguese man – of – war’ Why?

Phylum 3. Ctenopiiora (Gr. knows = comb; photos = bearing) (Animals with comb plate)

Ctenopiiora Salient features :

1. They are diploblastic animals.
2. The body is formed of eight ciliated comb plates that act as locomotory organs.
3. They have some special adhesive collision between the tentacles known as coil blast cells or Lasso cells.

Ctenopiiora  Examples: Hormiphora (Hormiphora sp.); Beroe (Beroe sp.)

• The smallest major phylum of the animal kingdom is Ctenophora. ; java yi Ctenophores are commonly known as ‘sea walnut’.
• Please know from your teacher Ctenophores exhibit bioluminescence” What
  does it mean?
• Do you-know-that’Ctiidaria and ctenophore-together called Coelenterata in the old Classification of animal-kingdom

Phylum 4. Piatyheimintries (Gr. Piaijys = flat; hernias = worms) (Flatworm or tapeworm)

Piatyheimintries Salient features:

1. The body is thin, dorsoventrally f.vjvflat, triploblastic animals (First triploblastic animal in the evolution of the animal kingdom).
2. Bilaterally symmetrical, acoelomate body hermaphrodite animals (bisexual animal)
3. Execution by Flame Cell

Piatyheimintries Examples: Liver fluke (Fasciola hepatica); Pig tapeworm [Taenia solium)

Phylum 5. Nematoda or Nemathelmipthes or Aschelrninthes (Gr. IMernatos = thread ) (Roundworm)

Nematoda Salient features:

1. Long cylindrical body with an alimentary canal that starts in the mouth and ends in the anus.
2. Pseudocoelomste animals with bodies covered with cuticles.
3. Generally, the sexes are separate.

Nematoda Examples: Roundworm (Ascaris lumbricoides) Filaria worm (Wuchereria bancrofti)

Write two common causes of infection of roundworm in children.

Phylum 6. Annelida (L. Annulus – ring; eidos = form) (Animals with ringlike body segments)

Annelida Salient features:

1. Elongated. body with numerous, ringlike segments called metamere.
2. Triploblastic animals with true coelom.
3. Excretion bynephrkiia.

Annelida Examples:

• Earthworm
• Leech

One special annelids is called “sea mouse’. Do you know its scientific name?

What is the importance of coelom?  In this body cavity different viscera! and abdominal organs (apart from the alimentary canal) are accommodated.

Phylum 7. Arthropods (Gr. Arthron = joint; pods = foot) (Animals with jointed appendage)

Arthropods’ Salient features :

1. Appendages are attached to the body by Arthrodia! membrane.
2. Open blood circulation within the body cavity is called hemocoel.
3. The body is covered with a chitinous exoskeleton.

Arthropods Examples:

1. Cockroach [Periplaneta americana)
2. Tiger Prawn (Penaeus monodon)

Besides the main axis of the body (Head, Thorax, and Abdomen), all additional organs (attachments) are called appendages.

Arthropods are the largest phylum of the animal kingdom. Make a list of insects of your own. locality. Identify in which season they flourish in number. Write a small note on economically important insects and their uses. Have you seen the scorpion in Satyajit Roy’s ‘Sonar Keila’?

For reference only:

Phylum 8. Mollusca (L. Mollis = Soft): (Soft unsegmented body covered with a calcareous exoskeleton)

Mollusca Salient features:

1. Soft, unsegmented bodies in the animals.
2. The body is covered with hard calcareous exoskeleton in most of them.
3. The visceral mass is enclosed by a muscular fold called a mantle.

Mollusca Examples:

1. Apple snail (Pila globosa)
2. Octopus (Octopus lentus)

Pearl is produced by pearl oyster which is a Mollusca. Do you know what is the major component of a pearl? Octopus is commonly known as ‘devil fish’.

What is the common name of Loligo? Please remember Phylum Mollusca is the second largest phylum of the animal kingdom.

Do you remember octopus ‘Paul’, the extraordinary predictor?

Phylum 9. Echmodermata (L. Echinos = spine; derma = skin) (Animals with calcareous spines in the skin)

Echmodermata Salient features:

1. The body is covered with skin having hard calcareous spines or ossicles.
2. Exclusively marine with pentamerous radial symmetry
3. Presence of special water vascular system or ambulacral system with tube feet.

Echmodermata Examples:

1. Starfish (Asterias rubens)
2. Sea cucumber (Cucumaria frondosa)

Difference between Diploblastic and Triploblastic animals:

Comparison between Cnidaria and Ctenophora :

1. Both of them are diploblastic.
2. Almost all of the marine animals.

Comparison between Platyhelminthes and Aschelminthes

Platyhelminthes and Aschelminthes Similarities: Almost all of them are parasitic

Platyhelminthes and Aschelminthes Difference

How is Porifera different from other animals? Porifera is multicellular like other animals but Porifera does not form any tissue hence all the cells are almost independent and live together like a colony of cells. In other multicellular animals. number of cells together form a tissue having a specific structure and function.

Difference between Coelomata And Psedocoelomata

Difference between Annelida and Arthropoda.

Salient features:

1. Worm-like marine animals, bilaterally symmetrical, triploblastic.
2. The body is cylindrical and is composed of a proboscis, collar, and a long trunk.
3. A notochord-like structure called stomochord is present.

Examples: Balanoglossus sp, Saccoglossus sp.

Do you know previously Hemichordata was included under Chordata but now it is ordered as a separate phylum and is not included under Chordata?

Example: All vertebrates including human beings

• “All vertebrates are chordates but all chordates are not vertebrates please reflect on the statement.
• Protochordata = Subphylum Urochordata + Subphylum Cephalochordata.

Subphylum Urochordata :

Subphylum Urochordata  Salient features :

1. Two openings on the body surface mouth and atriopore
2. Notochord is present only in larval tail
3. Larva undergoes retrogressive metamorphosis to form an adult.

For reference only: Metamorphosis is the process by which a larva undergoes structural, functional, physiological, and biochemical changes to be gradually transformed into an adult. If a simple larva is transformed into a complex adult, it is called progressive metamorphosis (for example caterpillar →butterfly).

On the contrary, if a complex larva is transformed into a simple adult, the process is called retrogressive metamorphosis (for example Tadpole larva, Ascidia).

Subphylum Urochordata  Example: Ascidia sp. Salpa sp.

Subphylum Cephalochordata (Acraniata):

Subphylum Cephalochordata Salient features:

1. Notochord extends from head to tail region and is persistent throughout life.
2. Fish like marine animals,
3. shaped myotome muscles are present.

Subphylum Cephalochordata Example: Amphioxus sp, Asymmetron sp.,

Subphylum Vertebrata (Craniata):

Subphylum Vertebrata Salient features:

1. Presence of endoskeleton made of bones and cartilage.
2. Presence of cranium or brain box that accommodates brain.
3. Presence of dorsal vertebral column formed of vertebrae.

Subphylum Vertebrata Examples: Shark, Rohu, Frog, Lizard, Birds, Guineapig, etc.

Division Agnatha : (A = without; gnathos = Jaw) (Jawless animal)

Salient features :

1. Mouth is circular (Cyclostomata : Cycios = circular; stoma = mouth)
2. Absence of surrounding mouth.
3. No paired fins and fins are without fin rays.

Examples:

• Lamprey (Pctromyzon marinus)
• Hag fish (Myxine glutinosa)
• Division Gnathostomata : (Gnathos = jaw; stoma = mouth)(Animals with jaw)

Salient features:

1. The mouth is guarded by the upper and lower jaw.
2. Skeletons are mostly made of bones.
3. Respiration by i; ills or lungs

Example: Fish, Amphibia, Reptilia, Aves, Mammalia.

Class 1. Chondrichthyes (Gr. chondromas = Cartilage; icthyes = Fish) (Fishes having cartilaginous skeletons)

Chondrichthyes Salient features:

1. The endoskeleton completely cartilaginous.’s; bone absent
2. Gill slits are without operculum; the mouth is centrally placed.
3. In marine animals where the body is covered with placoid scales; no air bladder.

Chondrichthyes Example:

• Dogfish shark (Scoliodon sp)
• Sting ray (Trygon sp)

Electric ray fish can cause electric shock for defense. Do you know? Famous Australian animal lover Steve Irwin died by the sting of a sting ray.

Class 2. Osteichthyes (Gr. Osteon ~ Bone; icthyes = Fish) (Bony fish)

Osteichthyes Salient features:

1. Skin is covered with cycloid or ctenoid scales.
2. Gills are covered by operculum presence of ait blades to maintain hydrostatic balance.
3. Two chambered venous hearts that always contain deoxygenated blood.

Osteichthyes Example:

1. Rohu Fish (Labeo rohita)
2. Katla Fish (Catla catla)

You should know fish oil contains HDL (High-Density Lipoprotein) which is very good for our hearts. HDL is also called good cholesterol.

Class 3. Amphibia (Gr. Amphi = both; bios = life)

(Animal that can live both on land and in? water)

Amphibia Salient features: 

1. Skin moist, glandular, and inked.
2. Heart three chambered two auricles and one ventricle.
3. For sexual reproduction and larval life, water is needed.

Amphibia Example:

1. Frog (Rana tiger in a)
2. Salamander (Ambystoma sp)

Do you know Axolotl larva can reproduce even in larval conditions—a very important specialty known as Neoteny or Paedogenesis? ‘

Class 4. Reptilia (L. Repere = to creep) (Vertebrates with creeping or crawling habit)

Reptilia Salient features:

1. Presence of two pairs ofoentadactyle limbs with claws that help in crawling locomotion.
2. Dry skin covered withcornfnedepidermai scales.
3. Heart three and a half chambered (four-chambered in crocodile).

Reptilia Example:

1. Garden Lizard (Calotes versicolor)
2. Cobra (Naja naja) Tautonym

Salient features:

1. Presence of a pair of mammary glands which is enlarged in females. This gland is a modified sweat gland.
2. The body is covered with hair a pair of external ears or pinna is present.
3. Heart completely four-chambered; matured RBC nonnucleated; diaphragm separates thorax and abdomen.

Example : Tiger (Panthera tigris) Man (Homo sapiens sapiens)

(Latin, Homo = man ; Sapiens = wise) This means Very wise man

The most fascinating extinct animal of the Jurassic period Dinosaurus (Terrible lizard) belonged to the class Reptilia.

For reference only:

Class Aves (L. Avis = bird)

(Common flying vertebrates)

Salient features:

1. The body is covered with feathers and the forelimb is modified into wings for flight.
2. Bones are hollow, pneumatic, and lighter in weight; the heart is completely four-chambered.
3. Presence of horny, hard beak without teeth.

Example: Pigeon (Columba livia)

Peacock (Pavo cristatus)

• A penguin is a bird from Antarctica, that cannot fly.
• Do you observe any peculiarity of ostrich?
• Do you know the ostrich egg is the largest single animal cell”?
• Running birds are called Ratitae and Flying birds are called carinatae.

Class 6. Mammalia (L. Mammalis = breast) (The highest evolved group of the animal kingdom)

Mammalia Salient features:

1. Presence of a pair of mammary glands which is enlarged in females. this gland is a modified sweat gland.
2. The body is covered with hair pair of external ear pinna prevent
3. Heart completely four-chambered matured RBC nonnucleated diaphragm separates thorax and abdomen.

Mammalia Example: Tiger(pantheraa tigris)

Man(homo Sapiens sapiens))Latin homo =man;sapiens =wise)This means very wise man

• Most of the mammals are viviparous.
• Do you know the name of any mammal that lays eggs?
• ‘Bat is a volant mammal’ Can you justify the statement?
• Whales and dolphins are aquatic mammals and not fish.
• Class Mammalia is divided into three subgroups
• Protothers (egg-laying mammals) example Platypus, Echidna
• Metatheria (females have marsupium) example Kangaroo
• Eutheria (females develop placenta during pregnancy) example Tiger, Man

The animals that lay eggs are called oviparous(for example Fish, Amphibia, Reptilia, Aves), and those who give birth to young ones directly are called viviparous(for example Mammalia).

Difference between Nonchordnta and Chordata

Difference Between Chondrichthyes And Osteichtyes

Difference between Amphibia and Reptilia.

“All vertebrates are chordates but all chordates are not vertebrates” justify the statement. In all vertebrates, chordate features are present in early embryonic life.

• Thus, there is a notochord which is gradually replaced by the vertebral column in the course of development.
• They have pharyngeal gill slits which may be persistent or replaced by lungs so all vertebrates are chordates.
• But all chordates are not vertebrates for example, in Urochordata and cephalochordate, the notochord is persistent throughout life and is never replaced by vertebra columns.
• Hence urocherdates and cephalochordates are chordates but not vertebrates.