Immunology and Host Defense Mechanisms MCQs

1. Which type of immunity is characterized by the production of antibodies against specific antigens?

a) Innate immunity
b) Passive immunity
c) Adaptive (acquired) immunity
d) Humoral immunity

Answer: d) Humoral immunity

2. What is the primary function of phagocytes in the immune system?

a) To produce antibodies
b) To destroy pathogens through engulfment and digestion
c) To regulate the immune response
d) To create memory cells

Answer: b) To destroy pathogens through engulfment and digestion

3. Which cells are primarily involved in cell-mediated immunity?

a) B cells
b) T cells
c) Erythrocytes
d) Platelets

Answer: b) T cells

4. What is the role of cytotoxic T cells (CD8+ T cells) in the immune response?

a) To produce antibodies
b) To activate other immune cells
c) To directly kill infected cells and cancer cells
d) To promote inflammation

Answer: c) To directly kill infected cells and cancer cells

5. Which class of immunoglobulins (antibodies) is most commonly found in the blood and provides long-term protection?

a) IgM
b) IgA
c) IgE
d) IgG

Answer: d) IgG

6. The complement system is a part of which type of immunity?

a) Innate immunity
b) Adaptive immunity
c) Passive immunity
d) Acquired immunity

Answer: a) Innate immunity

7. What is the primary function of natural killer (NK) cells in the immune system?

a) To produce antibodies
b) To phagocytize pathogens
c) To destroy infected or cancerous cells without prior sensitization
d) To activate B cells

Answer: c) To destroy infected or cancerous cells without prior sensitization

8. Which type of hypersensitivity reaction is mediated by IgE antibodies and involves an allergic response?

a) Type I hypersensitivity
b) Type II hypersensitivity
c) Type III hypersensitivity
d) Type IV hypersensitivity

Answer: a) Type I hypersensitivity

9. Which organ is primarily responsible for the maturation of T lymphocytes (T cells)?

a) Spleen
b) Bone marrow
c) Thymus
d) Lymph nodes

Answer: c) Thymus

10. What is the primary role of antigen-presenting cells (APCs) in the immune system?

a) To destroy pathogens
b) To present antigens to T cells for activation
c) To produce antibodies
d) To regulate inflammation

Answer: b) To present antigens to T cells for activation