NCERT Solutions For Class 8 Science Chapter 2 Microorganisms: Friend And Foe SAQs
Question 1. Ankur’s mother told him to wash his hands with soap before eating because his hands might have bacteria. Ankur did not believe her because he could not see anything on his hands. Why couldn’t Ankur see the bacteria on his hands? Why is washing hands with soap and water before eating generally recommended? State how bacteria can be harmful to humans.
Answer: Bacteria are too small and cannot be seen with the naked eye. They can be seen only with the help of a microscope.That’s why Ankur could not see the bacteria on his hands. Washing hands with soap and water can help to remove various bacteria and reduce the risk of infection. Bacteria can cause various diseases like dysentery, typhoid, cholera, etc.
NCERT Solutions for Class 8 Science Microorganisms SAQs
Question 2. Name two diseases that are caused by viruses.
Write one important characteristic of a virus.
Answer:
Influenza and chickenpox are two diseases caused by viruses in humans. Viruses can reproduce only inside the cells of a host, of an infected person.
Question 3. Yeast is very useful for the baking industry. Elucidate the role of yeast.
Answer: Yeast plays an important role in the baking industry. It reproduces rapidly and produces CO2 during respiration. Bubbles fill the dough and increase its volume, making the products such as bread, cake, and fluffy.
NCERT Solutions for Microorganisms Friend and Foe SAQs
Question 4. Justify with the help of two examples that microorganisms can be beneficial for humans.
Answer: Two examples that justify that microorganisms can be beneficial for humans are as follows
Baking industry. The dough for making bread, cakes and pastries is prepared by adding yeast to flour. Yeast reproduces rapidly and produces carbon dioxide during respiration. These gases fill the dough and increase its volume. It adds sponginess to cake and bread.
NCERT Class 8 Science Chapter 2 Microorganisms SAQs
Production of Antibiotics Antibiotics are produced by several groups of microbes, such as bacteria and fungi. These microbes produce antibiotics as their natural defense system against other microbes.
Question 5. Polio drops are not given to children suffering from diarrhoea. Why?
Answer: If the child is suffering from diarrhoea, the polio drops that are orally given vaccine may be excreted because of frequent motions and thus become ineffective.