MCQs MICROBIOLOGY: Immune System

1.
Large parasites such as helminthes may be killed extracellularly by the action of

A. basophils B. monocytes
C. eosinophils D. neutrophils
Answer & Explanation
Answer: Option C

2.
Which of the following is correct for CD8 T cells?

A. CD8 T cells only recognize virus-infected cells
B. CD8 T cell receptor recognizes epitopes that are also commonly recognized by B cells
C. In the thymus, CD8 T cells undergo positive selection only, whereas CD4 T cells undergo negative selection only
D. CD8 T cells can kill individual virus-infected cells in a contact dependent fashion
Answer & Explanation
Answer: Option D

3.
Passive immunization is done for

A. tuberculosis
B. diphtheria
C. enteric fever
D. all of these
Answer & Explanation
Answer: Option B

4.
Which of the following is correct for isoantigens?

A. They are antigens found in all members of different species
B. They are antigens found in some members of a species
C. They are antigens found in all members of a species
D. They are antigens found in some members of different species
Answer & Explanation
Answer: Option B

5.
Numerous antibodies can be prepared, against one antigen, each binds to unique epitopes. How is this antibody diversity generated?

A. By rearrangements of the DNA encoding the variable regions of the heavy and light chains
B. By the combination of different heavy and light chains that form the antigen binding site
C. Antibody proteins can physically change their shape to bind different epitopes
D. Both (a) and (b)
Answer & Explanation
Answer: Option D

6.
Which of the following expresses CD3 surface antigen?

A. Granulocytes
B. T cells
C. Monocytes
D. B cells
Answer & Explanation
Answer: Option B

7.
Polymorphonuclear leukocytes (or PMNs)

A. can be attracted to the site of an infection following activation of complement
B. are derived from bone marrow stem cells
C. are a type of phagocyte that can engulf and kill bacteria
D. all of the above
Answer & Explanation
Answer: Option D

8.
Major Histo Compatibility Complex (MHC) is a collection of genes arrayed on

A. chromosome 21 in man, chromosome 6 in mice
B. chromosome 6 in man, chromosone 21 in mice
C. chromosome 17in man, chromosome 6 in mice
D. chromosome 6 in man, chromosome 17 in mice
Answer & Explanation
Answer: Option D

9.
CD8 surface antigen is present in

A. cytotoxic T cells
B. suppresssor T cells
C. both (a) and (b)
D. none of these
Answer & Explanation
Answer: Option C

10.
Treatment with bacterial endotoxins results blast formation in

A. B cells
B. T cells
C. monocytes
D. none of these
Answer & Explanation
Answer: Option A

11.
Cytotoxic T-cells can be recognized by which of the following cell surface marker?

A. CD4 B. CD7
C. CD8 D. CD9
Answer & Explanation
Answer: Option C

12.
Which is not an antigen-presenting cell (or APC)?

A. B cell
B. Polymorphonuclear leukocyte (or PMN)
C. Dendritic cell
D. All of the above
Answer & Explanation
Answer: Option B

13.
Chemically an antigen may be

A. lipid
B. protein
C. polysaccharide
D. any of these
Answer & Explanation
Answer: Option D

14.
T cell receptors (or TCR) on CD4+ T cells

A. recognize peptides not associated with MHC molecules
B. recognize peptides associated with MHC class I molecules
C. recognize peptides associated with MHC class II molecules
D. are secreted out into the environment to bind antigens
Answer & Explanation
Answer: Option C

15.
Which of the following proteins would not need localization signal?

A. A nuclear protein
B. A cytosolic protein
C. A protein bound to the endoplasmic reticulum (ER) membrane
D. A cell surface protein
Answer & Explanation
Answer: Option B

16.
Following are the defenses of the colon except

A. sIgA
B. fast flow rate
C. dense resident microbiota
D. mucus
Answer & Explanation
Answer: Option B

17.
Natural killer cells are involved in

A. tumour rejection
B. allograft rejection
C. non-specific killing of virus transformed target cells
D. all of these
Answer & Explanation
Answer: Option D

18.
Which of the following(s) is/are the determinants of antigenicity?

A. Chemical nature
B. Size of the antigen
C. Foreignness
D. All of these
Answer & Explanation
Answer: Option D

19.
Which of the following is correct?

A. All T Cells are CD4+
B. An epitope can have multiple antigens
C. T Cell receptors are generated by random assortment of gene cassettes
D. MHC Class II molecules are generated by random assortment of gene cassettes
Answer & Explanation
Answer: Option C

20.
Immunity is not long lasting to

A. influenza
B. whooping cough
C. diphtheria
D. mumps
Answer & Explanation
Answer: Option A

21.
Lysozyme is present in

A. sweat
B. Cerebro spinal fluid (CSF)
C. urine
D. saliva
Answer & Explanation
Answer: Option D

22.
Macrophages are professional antigen- presenting cells. The protein molecule through which they present antigen in human is

A. actin B. interleukin
C. HLA D. CD8
Answer & Explanation
Answer: Option D

23.
The role of the M cell is to

A. trap virus in mucus and prevent entry
B. induce apoptosis in virus-infected small intestinal epithelia cells
C. pass bacteria or virus to underlying macrophages for processing and presentation of antigen
D. they use their cilia to propel mucus out of the small intestine
Answer & Explanation
Answer: Option C

24.
Which of the following statements is false regarding B cells?

A. B cells can undergo class switching and produce a different antibody type
B. B one marrow stem cells migrate to the thymus and develop into B cells
C. B cells synthesize antibodies and put them on their cell surface
D. B cells that recognize high concentrations of antigens (self) in the absence of other signals undergo apoptosis in the bone marrow
Answer & Explanation
Answer: Option B