Question 1

Which of the following best describes the role of the skin and mucous membranes in the immune system?

Accepted Answer

They serve as the first line of defense by providing mechanical and chemical barriers against pathogens.

Question 2

A patient with a genetic deficiency in complement protein C3 would most likely experience which of the following?

Accepted Answer

Impaired cytolysis, opsonization, and inflammation, leading to increased susceptibility to infections.

Question 3

Which equation best represents the activation of complement protein C3?

Accepted Answer

$$\mathrm{C3} \rightarrow \mathrm{C3a} + \mathrm{C3b}$$

Question 4

Which of the following is NOT a function of phagocytosis?

Accepted Answer

Production of antibodies against pathogens.

Question 5

A virus-infected cell presents abnormal endogenous antigens on its surface. Which immune cell is primarily responsible for recognizing and killing this cell?

Accepted Answer

Cytotoxic T lymphocyte (CTL, CD8+)

Question 6

Which of the following statements about haptens is correct?

Accepted Answer

Haptens are small molecules that become immunogenic only when attached to a carrier protein.

Question 7

Which equation best represents the formation of an antigen–antibody complex?

Accepted Answer

$$\mathrm{Ag} + \mathrm{Ab} \rightarrow \mathrm{AgAb}$$

Question 8

Which of the following is a key difference between humoral and cellular immunity?

Accepted Answer

Humoral immunity targets pathogens outside cells, while cellular immunity targets pathogens inside cells.

Question 9

Which of the following best describes the process of opsonization?

Accepted Answer

Coating a pathogen with antibodies or complement proteins to enhance phagocytosis.

Question 10

A patient receives a vaccine containing inactivated viral particles. Which type of immunity is being induced?

Accepted Answer

Artificially acquired active immunity

Question 11

Which of the following cytokines is primarily involved in the inflammation of autoimmune diseases?

Accepted Answer

Tumor necrosis factor (TNF)

Question 12

Which equation best represents the antibody titer in serum over time after initial and secondary exposure to an antigen?

Accepted Answer

$$	ext{Antibody titer}_{	ext{secondary}} \u003e 	ext{Antibody titer}_{	ext{primary}}$$

Question 13

Which of the following is a result of antigen–antibody binding?

Accepted Answer

Agglutination, opsonization, neutralization, and activation of complement.

Question 14

Which of the following best explains why protozoans and helminths are attacked externally by the immune system?

Accepted Answer

They are too large to be phagocytized, so immune cells attach to antibodies coating their surface and release lytic enzymes.

Question 15

Which of the following is true regarding the Major Histocompatibility Complex (MHC)?

Accepted Answer

Class I MHC molecules are found on all nucleated cells and identify 'self'.

Question 16

Which of the following best describes the function of interferons?

Accepted Answer

They induce neighboring cells to produce antiviral proteins that inhibit viral replication.

Question 17

Which of the following is a distinguishing property of adaptive immunity?

Accepted Answer

Specificity and memory

Question 18

Which of the following best describes the process of clonal selection in B cells?

Accepted Answer

B cells that recognize an antigen undergo proliferation and differentiate into plasma cells and memory cells.

Question 19

Which of the following is a plausible consequence of a cytokine storm?

Accepted Answer

Excessive immune activation leading to tissue damage and potentially fatal inflammation.

Innate and Adaptive Immunity: Defenses of the Host

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