Question 1

Which of the following best describes the difference between a complete antigen and an incomplete antigen (hapten)?

Accepted Answer

A complete antigen can stimulate an immune response on its own, while an incomplete antigen must bind to a body protein to become immunogenic.

Question 2

A patient receives a kidney transplant and is prescribed immunosuppressive drugs. Despite this, the organ is rejected after several weeks. Which immune process is primarily responsible for this rejection?

Accepted Answer

Cell-mediated immunity involving cytotoxic T cells recognizing foreign MHC class I molecules.

Question 3

Which of the following best explains the process of opsonization during complement activation?

Accepted Answer

Coating of pathogens with complement proteins to enhance phagocytosis by immune cells.

Question 4

A child is born with a genetic defect resulting in the absence of T cells. Which of the following best describes the likely consequence?

Accepted Answer

Severe immunodeficiency, similar to Severe Combined Immunodeficiency (SCID), leading to increased susceptibility to infections.

Question 5

Which of the following is a key difference between the classical and alternative pathways of complement activation?

Accepted Answer

The classical pathway is triggered by antigen-antibody complexes, while the alternative pathway is triggered by pathogen surfaces.

Question 6

During inflammation, which sequence of events occurs first?

Accepted Answer

Release of inflammatory chemicals such as histamine and prostaglandins.

Question 7

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

Accepted Answer

They are released by virus-infected cells to protect neighboring cells by inducing synthesis of antiviral proteins.

Question 8

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

Accepted Answer

Artificially acquired passive immunity

Question 9

Which immunoglobulin class is produced first during a primary immune response and is most effective at agglutinating antigens?

Accepted Answer

IgM

Question 10

Which of the following best describes the difference between cytotoxic T cells and natural killer (NK) cells?

Accepted Answer

Cytotoxic T cells recognize antigen presented by MHC class I, while NK cells can kill cells lacking MHC class I.

Question 11

Which of the following is an example of a type I hypersensitivity reaction?

Accepted Answer

Allergic reaction to pollen resulting in hay fever

Question 12

Which statement best describes the process of positive selection during T cell education in the thymus?

Accepted Answer

T cells that can recognize self-MHC molecules survive; those that cannot undergo apoptosis.

Question 13

Which of the following cells function as antigen-presenting cells (APCs) and how do they contribute to the immune response?

Accepted Answer

Dendritic cells, macrophages, and B cells; they process and present antigens to T cells to initiate adaptive immunity.

Question 14

A patient is exposed to the influenza virus for the second time. Which immunoglobulin is most abundant in the secondary response, and why is the response faster?

Accepted Answer

IgG; memory B cells rapidly differentiate into plasma cells upon re-exposure.

Question 15

Which of the following best describes the mechanism of antibody neutralization?

Accepted Answer

Antibodies bind to specific sites on pathogens or toxins, blocking their ability to bind to host cells.

Question 16

Which of the following is true regarding MHC class II proteins?

Accepted Answer

They are found on antigen-presenting cells and present antigens to helper T cells.

Question 17

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

Accepted Answer

A B cell with a specific receptor binds its antigen, proliferates, and differentiates into plasma and memory cells.

Question 18

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

Accepted Answer

They activate both B cells (humoral immunity) and cytotoxic T cells (cellular immunity).

Question 19

Which of the following best describes the difference between active and passive humoral immunity?

Accepted Answer

Active immunity involves the production of antibodies by the individual's own immune system, while passive immunity involves receiving antibodies from another source.

Question 20

A patient develops a fever in response to a bacterial infection. Which of the following best explains the physiological benefit of fever?

Accepted Answer

Fever increases the metabolic rate, enhancing tissue repair and inhibiting bacterial growth.

Chapter 21: The Immune System – Innate and Adaptive Body Defenses

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