Question 1

Which of the following best describes the role of dendritic cells in the adaptive immune response?

Accepted Answer

They act as antigen-presenting cells that bridge innate and adaptive immunity by presenting processed antigens to T cells.

Question 2

A patient receives a vaccine containing an inactivated virus. Which immune response is primarily responsible for the long-term protection provided by this vaccine?

Accepted Answer

The production of memory B and T cells during the primary response.

Question 3

Which of the following statements about Major Histocompatibility Complex (MHC) molecules is CORRECT?

Accepted Answer

MHC I molecules present endogenous antigens to CD8+ T cells.

Question 4

A virus infects a cell and viral proteins are synthesized inside the host cell. Which pathway will present these viral antigens to the immune system?

Accepted Answer

The endogenous pathway via MHC I molecules.

Question 5

Which antibody class is most effective at activating the complement system and is the first produced during a primary immune response?

Accepted Answer

IgM

Question 6

A patient with a genetic defect in MHC II expression would have the most difficulty with which of the following immune processes?

Accepted Answer

Activation of helper T cells by exogenous antigens.

Question 7

Which of the following best explains why antibodies are ineffective against viruses that have already entered host cells?

Accepted Answer

Antibodies cannot cross the plasma membrane to reach intracellular viruses.

Question 8

Which of the following is a function of regulatory T cells in the immune response?

Accepted Answer

They suppress immune responses to prevent excessive reactions after antigen clearance.

Question 9

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

Accepted Answer

B cells that encounter their specific antigen proliferate and differentiate into plasma and memory cells.

Question 10

Which of the following is NOT a function of antibodies?

Accepted Answer

Direct killing of infected cells by releasing perforin.

Question 11

A patient is exposed to the same pathogen for a second time. Which of the following best describes the immune response?

Accepted Answer

The secondary response is faster and more robust due to memory cells.

Question 12

Which of the following best distinguishes natural killer (NK) cells from cytotoxic T (TC) cells?

Accepted Answer

TC cells kill only cells presenting specific antigen-MHC I complexes, while NK cells kill cells lacking self-MHC I.

Question 13

Which of the following is a correct sequence of events in the activation of a cytotoxic T cell?

Accepted Answer

Recognition of antigen-MHC I complex, activation by cytokines, release of perforin and granzymes.

Question 14

Which antibody class is most abundant in blood and extracellular fluid and can cross the placenta to provide passive immunity to the fetus?

Accepted Answer

IgG

Question 15

Which of the following best describes the role of cytokines in the immune response?

Accepted Answer

They are chemical messengers that regulate the intensity and duration of immune responses.

Question 16

Which of the following is TRUE regarding the difference between humoral and cell-mediated immunity?

Accepted Answer

Humoral immunity targets extracellular pathogens, while cell-mediated immunity targets infected or abnormal cells.

Question 17

Which of the following best explains why IgA is important at mucosal surfaces?

Accepted Answer

IgA is secreted at epithelial mucosal surfaces and neutralizes pathogens before they enter the body.

Question 18

Which process ensures that lymphocytes that react with self-antigens are eliminated during development?

Accepted Answer

Central tolerance

Question 19

Which of the following is a direct result of antibody opsonization?

Accepted Answer

Enhanced phagocytosis of the pathogen by immune cells.

Specific (Adaptive) Immunity: Mechanisms, Cells, and Responses

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