Question 1

Which of the following best describes the difference between endogenous and exogenous antigens?

Accepted Answer

Endogenous antigens are produced by microbes that reproduce inside a body’s cells, while exogenous antigens are toxins and components of microbial cell walls, membranes, flagella, and pili.

Question 2

A patient receives a vaccine and later is exposed to the same pathogen. Which characteristic of adaptive immunity allows for a faster and stronger response upon this second exposure?

Accepted Answer

Memory

Question 3

Which of the following is TRUE regarding the function of antibodies in the immune response?

Accepted Answer

Antibodies can neutralize toxins by binding to critical portions, preventing them from interacting with host cells.

Question 4

Which class of antibody is most abundant in serum and is the only one that can cross the placenta to protect the fetus?

Accepted Answer

IgG

Question 5

A newborn is found to have IgM antibodies against a specific pathogen in their blood. What does this most likely indicate?

Accepted Answer

The newborn was infected with the pathogen in utero.

Question 6

Which of the following best describes the role of Major Histocompatibility Complex (MHC) molecules in adaptive immunity?

Accepted Answer

They present antigenic peptides to T cells, allowing the immune system to distinguish self from non-self.

Question 7

Which of the following is a function of cytotoxic T cells (Tc)?

Accepted Answer

They directly kill virus-infected cells and tumor cells.

Question 8

A patient with a deficiency in regulatory T cells (Treg) is most likely to experience which of the following?

Accepted Answer

Increased risk of autoimmune diseases due to lack of immune suppression.

Question 9

Which of the following best explains why IgA is important in mucosal immunity?

Accepted Answer

IgA is secreted as a dimer and is found in body secretions, where it agglutinates and neutralizes pathogens.

Question 10

Which of the following cytokines is primarily responsible for signaling among leukocytes?

Accepted Answer

Interleukins (ILs)

Question 11

A laboratory test detects high levels of IgE in a patient’s serum. Which of the following conditions is most likely present?

Accepted Answer

Allergic reaction or parasitic infection

Question 12

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

Accepted Answer

Activated lymphocytes proliferate to form many identical cells specific to an antigen.

Question 13

Which of the following is a key difference between natural killer (NK) cells and cytotoxic T cells?

Accepted Answer

NK cells do not require prior exposure to antigen, while cytotoxic T cells do.

Question 14

Which of the following best describes the role of helper T cells (Th) in the immune response?

Accepted Answer

They regulate the activity of B cells and cytotoxic T cells by secreting cytokines.

Question 15

A patient receives an injection of antiserum containing antibodies against a toxin. What type of immunity is this?

Accepted Answer

Artificially acquired passive immunity

Question 16

Which of the following best explains why the secondary immune response is faster and stronger than the primary immune response?

Accepted Answer

Memory cells generated during the primary response quickly recognize and respond to the antigen.

Question 17

Which of the following is TRUE about the structure of an antibody molecule?

Accepted Answer

It consists of two identical heavy chains and two identical light chains, with variable regions forming the antigen-binding sites.

Question 18

Which of the following is a function of the Fc region of an antibody?

Accepted Answer

It binds to receptors on phagocytes and triggers complement activation.

Question 19

Which of the following best describes the process of opsonization?

Accepted Answer

Antibodies coat pathogens, enhancing their uptake and destruction by phagocytes.

Question 20

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

Accepted Answer

Antigen presentation, helper T cell differentiation, clonal expansion, self-stimulation

Adaptive Immunity: Mechanisms and Components

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