Question 1

Which of the following best describes the main difference between the cellular and humoral branches of the adaptive immune system?

Accepted Answer

The cellular branch is mediated by T cells that directly destroy infected or abnormal cells, while the humoral branch is mediated by B cells that produce antibodies.

Question 2

A patient receives a preparation of antibodies after being bitten by a venomous snake. Which type of immunity is this an example of?

Accepted Answer

Artificially acquired passive immunity

Question 3

Which of the following statements about antigen-presenting cells (APCs) is correct?

Accepted Answer

APCs present antigens to T helper cells using MHC II molecules.

Question 4

Which antibody isotype is most abundant in human blood and is responsible for long-term immunity after vaccination?

Accepted Answer

IgG

Question 5

A patient with a parasitic worm infection is found to have elevated levels of which antibody isotype?

Accepted Answer

IgE

Question 6

Which of the following best explains why haptens, such as penicillin, can trigger an immune response only when attached to a larger carrier molecule?

Accepted Answer

Haptens are incomplete antigens and lack sufficient molecular complexity to be immunogenic alone.

Question 7

Which process ensures that developing T cells do not attack the body’s own tissues?

Accepted Answer

Self-tolerance screening in the thymus

Question 8

A patient is exposed to a pathogen for the first time. Which antibody isotype will be produced first, and which will predominate during a secondary exposure?

Accepted Answer

IgM first, IgG second

Question 9

Which of the following is a function of T helper 1 (TH1) cells?

Accepted Answer

Activate T cytotoxic cells, macrophages, and natural killer cells to destroy intracellular pathogens

Question 10

A tissue transplant recipient develops graft-versus-host disease (GVHD). Which immunological process is most likely responsible for this complication?

Accepted Answer

The donor’s immune cells attack the recipient’s tissues due to recognition of foreign MHC molecules.

Question 11

Which of the following best describes the role of memory cells in adaptive immunity?

Accepted Answer

They remain in lymphatic tissues and enable a rapid, amplified response upon re-exposure to the same antigen.

Question 12

Which of the following is a correct statement about MHC molecules?

Accepted Answer

MHC II presents extracellular antigens to CD4+ T helper cells.

Question 13

Which of the following is a real-world example of artificially acquired active immunity?

Accepted Answer

Receiving a vaccine against measles

Question 14

Which of the following best explains why siblings are not guaranteed to be compatible tissue donors?

Accepted Answer

MHC genes are highly variable and inherited independently, so siblings may have different MHC profiles.

Question 15

Which of the following is a possible consequence of superantigen exposure?

Accepted Answer

A broad, nonspecific activation of T helper cells leading to dangerous cytokine release

Question 16

Which of the following best describes the process of opsonization?

Accepted Answer

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

Question 17

A patient’s blood test shows high levels of IgM but low levels of IgG to a specific pathogen. What does this most likely indicate?

Accepted Answer

The patient is in the early stages of a primary immune response.

Question 18

Which of the following is a function of plasma cells?

Accepted Answer

Secrete large quantities of antibodies specific to the activating antigen

Question 19

Which of the following best explains why a patient with acute lymphoblastic leukemia (ALL) may have low antibody titers despite an increased number of B lymphocytes?

Accepted Answer

The B lymphocytes are immature and unable to differentiate into functional plasma cells.

Question 20

Which of the following is a correct sequence of events in the adaptive immune response?

Accepted Answer

Antigen presentation → Lymphocyte activation → Lymphocyte proliferation and differentiation → Antigen elimination and memory

Adaptive Immunity: Principles and Mechanisms

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