Microbiology And Immunology Multiple Choice Questions And Answers

Question 1. Toll-like receptors: correct statement is:

1. Antigen-specific
2. Acts by cytokine release
3. Part of adaptive immunity
4. Facilitates microbial invasion

Answer. (2) (Acts by cytokine release)

Read And Learn More: Micro Biology And Immunology Multiple Choice Question And Answers

TLR is receptor of innate immunity, antigen nonspecific. These are signals generated following binding of TLRs to MAMPs activate transcription factors that stimulate expression of genes encoding cytokines and enzymes, which are involved in several antimicrobial activities of cells of innate immunity.

Question 2. Not true about innate immunity:

1. Not influenced by hormones
2. Dependent on genetic constitution
3. Identical twins have same degree of resistance
4. Not influenced by exposure to antigen

Answer. (1) (Not influenced by hormones)

• Innate immunity is influenced by hormones: Endocrine disorders like diabetes are associated with enhanced susceptibility to infection due to altered innate immunity.
• Innate immunity is dependent on genetic constitution of the individual. Homogenous identical twins exhibit similar degree of innate immunity.
• Innate immunity is nonspecific, it is not influenced by exposure to antigen.

Question 3. All are true about innate immunity except:

1. Acts as first line of defense
2. Complements are examples
3. Nonspecific
4. Not effected by genetic influences

Answer. (4) (Not effected by genetic influences)

• Innate immunity refers to the resistance to infection that an individual possess from birth by its genetic or constitutional make up.
• Other options are correct- for explanation, refer text.

Question 4. Transfer factor is an example of:

1. Artificial active immunity
2. Natural active immunity
3. Adoptive immunity
4. Artificial passive immunity

Answer. (3) (Adoptive immunity)

Adoptive immunity

Acquired by injection of immunologically competent T-lymphocytes known as Transfer factor

• Used for treatment when the CMI is low, e.g. Lepromatous leprosy.

Question 5. Components of innate immunity:

1. T lymphocyte
2. B lymphocyte
3. Complements
4. NK cells
5. Integrins

Answer. (3) (4) (5) (Complements, NK cells, Integrins)

• Complement pathways (alternate and mannose-binding, NK cells, and Pattern recognition receptors like Integrins are components of Innate immunity

Question 6. Innate immunity is stimulated by which part of bacteria?

1. Carbohydrate sequence in the cell wall
2. Flagella
3. Bacterial cell membrane
4. Nucleus

Answer. (1) (Carbohydrate sequence in cell wall)

• Pattern recognition receptors are important component of innate immunity
• Toll-like receptors are, e.g. of PRR Protein Family which bind to carbohydrate antigens on bacterial and viral surfaces.
  Examples of microbial ligands that bind to Pattern recognition receptors on host cells include:
• Bacterial and viral carbohydrates residues on cell wall
• Terminal mannose and Carbohydrate on HLA molecules
• Lipopolysaccharide (LPS)
• Viral DNA Bacterial muramyl dipeptide

Question 7. Innate immunity active against viral cells:

1. NK cells
2. Cytotoxic T cells
3. B cells
4. Memory B cell

Answer. (1) (NK cells)

• Natural killer cells are components of innate immunity
• Natural killer cells possess spontaneous cytotoxicity towards virus infected cells and malignant cells and their cytotoxicity is not antibody dependent nor MHC restricted
• About Other options: Cytotoxic T cells, B cells and Memory B cell are
• Components of adaptive/acquire immunity

Question 8. All of the following are a part of the innate immunity except:

1. Complement
2. NK cells
3. Macrophages
4. T cells

Answer. (4) (T cells)

• Alternate pathways of Complement , NK cells and Macrophages (as phagocytes) are the components of innate immunity
• B cell, T cell, Classical complement, and Antigen presenting cells are components of adaptive/acquired immunity.

Question 9. Active immunity can be induced by:

1. Toxoids
2. Subclinical infection
3. Antitoxin
4. Immunoglobulins
5. Antigen exposure

Answer. (1) (2) (5) (Toxoids, Subclinical infection, Antigen exposure)

• Active immunity can be induced by any substance that actively stimulates the immune system to produce antibody. Vaccines, toxoids, infection or antigen exposure can induce active immunity
• Antitoxin and immunoglobulins are, e.g. of Passive immunity.

Question 10. True about passive immunity:

1. Cannot be given with active immunity
2. Last for 4–5 days only
3. It can be given before disease occurrence
4. Can be transferred by antibodies from another Host
5. Takes longer time to develop

Answer. (3, 4) (It can be given before disease occurrence, Can be transferred by antibodies from another Host)

• Immunoglobulins can be given along with vaccine in postexposure prophylaxis, e.g.
• Rabies immunoglobulins
• Passive immunity last for days to months
• Immunoglobulins should be given immediately after the exposure but before the disease occurrence
• Passive immunity can be transferred between individuals by Serum therapy (antibodies)
• Passive immunity works immediately

Question 11. Superantigen is produced by:

1. Staphylococcus aureus
2. Streptococcus pneumoniae
3. Pseudomonas
4. Clostridium
5. Acute Phase Reactants and CRP

Answer. (1) (Staphylococcus aureus)

Question 12. Span Of C Reactive Protein Half-Life:

1. 18 hrs
2. 2 hrs
3. 12 hrs d. 15 hrs

Answer. (1) (18 hrs)

The plasma half-life of CRP is about 19 hours and is constant under all conditions of health and disease, so that the sole determinant of circulating CRP concentration is the synthesis rate.