Immunity Short And Long Essays Question And Answers

Immunity Important Notes

1. Types of immunity

  • Innate immunity
  • Acquired immunity
    • Types
      • Active immunity
        • Natural active
        • Artificial active
      • Passive immunity
        • Natural passive
        • Artificial passive

2. Antigens

  • Heterophile antigen
    • These are the same or closely related antigens present in different tissues of more than one species
  • Haptens
    • These are substances unable to induce antibody formation on its own but can be immunogenic when linked to carrier proteins
    • It is a partial/incomplete antigen

3. Immunoglobulin

  • These are substances which are formed in serum in response to an antigen
  • It consists of two heavy chains and two light chains held together by disulphide bonds

Immunoglobulin Classes

Immunity Immunoglobulin classes

Read And Learn More: Microbiology Question and Answers

4. Types of antigen-antibody reactions

Immunity Types of antigen-antibody reactions

5. Complement

  • It refers to a system of factors which occurs in normal serum and are activated by antigen-antibody reaction
  • It is triggered by two parallel pathway
  • Classical pathway
  • Alternate pathway

6. Interleukins (IL)

Immunity Interleukins

7. Hypersensitivity reactions

Immunity Hypetsensitivity reactions

8. Vaccines

Immunity Vaccines

Immunity Long Essays

Question 1. Define and classify immunity. Discuss acquired immunity.


1. Immunity:

  • It is defined as resistance exhibited by the host against any foreign antigen including micro-organisms.

Immunity Classification:

  • Immunity may be classified into different types as follows.

Immunity - Classify Immunity

2. Acquired immunity:


  • It is the resistance acquired by an individual during life.

Acquired immunity Types:

1. Active Immunity:

  • It is subdivided into two types.
    • Natural active immunity.
      • Acquired by natural subclinical or clinical infections.
      • It is long-lasting.
      • Example: A person recovering from smallpox develop natural active immunity.
    • Artificial active immunity.
      • Induced by vaccination.


  • Active immunity stimulates both humoral and cell-mediated immunity.

Immunity Stimulates between Humoral and Cell Mediated Immunity

2. Passive Immunity:

  • It is subdivided into two types:
    • Natural
      • Immunity is transferred from mother to fetus transplacentally.
    • Artificial
      • Occurs through the parenteral administration of antibodies.


  • It is induced in an individual by preformed vaccines against infective agents.
  • It is short lasting.
  • It is used when immunity is required immediately.


  • To provide immediate short-term protection
  • For suppression of active immunity.
  • For treatment of serious infection

Immunity Short Essays

Question 1. Innate immunity.

Innate immunity Definition:

  • It is the resistance which individual possesses by birth.

Innate Immunity Types:

  • Factors influencing it:

1. Age:

  • Infants have immature immunity, while during old age there is gradual decreases in immunity.
  • This increases susceptibility to infections.

2. Hormones:

  • Hormonal disorders may lead to increased susceptibility to infections.

3. Nutrition:

  • Malnutrition predisposes to infections.

Innate immunity Mechanism:

1. Epithelial surfaces:

  • Skin.
    • Act as a mechanical barrier to micro-organisms
    • Provides bacteriocidal secretions.
    • The resident bacterial flora prevents colonization by pathogens.
  • Respiratory tract.
    • Nasal passages arrest the inhaled particles.
    • The mucous secretions of the respiratory tract act as a trapping mechanism.
    • Cilia help to propel the particles toward the pharynx.
  • Intestinal tract.
    • Mouth – inhibits micro-organisms.
    • Acidic gastric pH – destroys bacteria.
    • Intestine – prevents colonization of bacteria,
  • Conjunctiva.
    • Tears flushes away bacteria and dust particles.
    • Lysozyme present in tears has bacteriocidal actions.
  • Genitourinary tract.
    • Urine eliminates bacteria.
    • Vaginal secretions destroy pathogens.
    • Semen contains antibacterial substances.

2. Antibacterial substances:

  • It includes properdin, complement, lysozyme, beta-lysin, basic polypeptides, and interferons.

3. Cellular factors:

  • Phagocytic cells ingest pathogenic organisms and de¬¨stroy them.

4. Inflammation:

  • It is a non-specific defense mechanism.
  • It phagocytoses and destroys micro-organism.

5. Fever:

  • Stimulates production of interferon

6. Acute phase proteins:

  • Activate alternate pathways of complement.

Immunity How To Opitimize Your immune System

Immunity Short Question And Answers

Question 1. Types of active immunity with examples.

Types of active immunity with examples

Immunity Active Immunity Types

Question 2. Difference between active and passive immunity

Difference between active and passive immunity

Immunity Differences between Active and passive immunity

Question 3. List two examples of Passive immunity.

Two examples of Passive immunity

Immunity Passive Immunity

Question 4. Define and classify antigens.

Antigen Definition:

  • The antigen is a substance which, when introduced into a body evokes an immune response to produce a specific antibody with which it reacts in an observable manner.

Antigen Types:

1. Complete antigen.

  • These can induced antibody formation by themselves.

2. Complete antigen.

  • These can induced antibody formation by themselves.

3. Incomplete antigen/haptens.

  • These are unable to induce antibody formation on their own.
  • But can become immunogenic when they are covalently linked to carrier proteins.

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