Question 1

Which of the following best describes the difference between MHC class I and MHC class II molecules in antigen presentation?

Accepted Answer

MHC class I molecules present endogenous antigens to cytotoxic T cells, while MHC class II molecules present exogenous antigens to helper T cells.

Question 2

A patient receives an injection of antibodies after a snake bite. Which type of acquired immunity is this an example of?

Accepted Answer

Artificially acquired passive immunity

Question 3

Which of the following is a key feature that distinguishes adaptive immunity from innate immunity?

Accepted Answer

Adaptive immunity has memory and is highly specific to individual antigens.

Question 4

Which antibody class is most abundant in body secretions such as saliva and breast milk, and what is its primary function?

Accepted Answer

IgA; protection of mucosal surfaces

Question 5

A mutation in the RAG enzyme would most likely result in which of the following consequences for B cell function?

Accepted Answer

Reduced diversity of B cell receptors (BCRs)

Question 6

Which of the following best explains why autoimmune diseases can develop if clonal deletion fails?

Accepted Answer

Self-reactive lymphocytes are not eliminated and may attack the body’s own tissues.

Question 7

Which of the following steps is NOT part of the activation of cytotoxic T cells?

Accepted Answer

Opsonization of pathogens

Question 8

A patient is exposed to a virus for the first time. Which antibody is produced first during the primary immune response, and what is the typical sequence of antibody production?

Accepted Answer

IgM is produced first, followed by IgG

Question 9

Which of the following is a function of antibodies that directly enhances phagocytosis by immune cells?

Accepted Answer

Opsonization

Question 10

Which cytokine is primarily responsible for signaling among leukocytes and is crucial for the coordination of the immune response?

Accepted Answer

Interleukin (IL)

Question 11

A patient receives a kidney transplant. Which molecules are most important in determining whether the transplant will be accepted or rejected?

Accepted Answer

Major histocompatibility complex (MHC) antigens

Question 12

Which of the following best describes the role of regulatory T cells in the immune system?

Accepted Answer

They repress adaptive immune responses to prevent autoimmunity.

Question 13

Which pathway involves the release of perforin and granzymes by cytotoxic T cells to induce apoptosis in target cells?

Accepted Answer

Perforin-granzyme pathway

Question 14

Which of the following statements about memory cells is TRUE?

Accepted Answer

Memory cells respond rapidly and effectively upon re-exposure to the same antigen.

Question 15

Which of the following is an example of an exogenous antigen?

Accepted Answer

A toxin secreted by a bacterium

Question 16

Which antibody class is primarily responsible for the secondary (anamnestic) immune response?

Accepted Answer

IgG

Question 17

Which of the following best explains why the adaptive immune response is described as 'clonal'?

Accepted Answer

Lymphocytes that recognize a specific antigen proliferate to form a population of identical cells.

Question 18

Which of the following is NOT a function of antibodies?

Accepted Answer

Direct killing of infected cells via apoptosis

Question 19

A child is born with a genetic defect that prevents the production of MHC class II molecules. Which immune function would be most directly impaired?

Accepted Answer

Activation of helper T cells by exogenous antigens

Question 20

Which of the following best describes the process of clonal deletion in the context of adaptive immunity?

Accepted Answer

The elimination of self-reactive lymphocytes during development

Adaptive Immunity: Structure, Function, and Mechanisms

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