Question 1

Which of the following best describes the role of Toll-like receptors (TLRs) in the innate immune system?

Accepted Answer

TLRs recognize fragments of molecules characteristic of a set of pathogens, triggering innate immune responses.

Question 2

A patient with a severe bacterial infection develops a dangerously high fever and a rapid increase in white blood cell count. Which immune response is most likely occurring?

Accepted Answer

A systemic inflammatory response, which may include fever and increased white blood cells.

Question 3

Which of the following is NOT a barrier defense of the innate immune system?

Accepted Answer

Antibodies circulating in the blood.

Question 4

What is the primary function of natural killer (NK) cells in vertebrate immunity?

Accepted Answer

To detect abnormal cells and release chemicals that induce cell death, inhibiting the spread of infected or cancerous cells.

Question 5

During the inflammatory response, mast cells release histamine. What is the effect of histamine on blood vessels?

Accepted Answer

Histamine triggers blood vessels to dilate and become more permeable, increasing blood flow and allowing immune cells to enter the tissue.

Question 6

Which process allows B cells to generate millions of different antigen receptors from a limited number of gene segments?

Accepted Answer

Random rearrangement of V (variable), J (joining), and C (constant) gene segments by recombinase.

Question 7

A newborn receives antibodies from its mother through breast milk. What type of immunity is this?

Accepted Answer

Passive immunity, because antibodies are transferred from mother to child.

Question 8

Which of the following statements about antigens and epitopes is correct?

Accepted Answer

An antigen is a substance that can elicit an immune response, and an epitope is the specific part of the antigen that binds to an antigen receptor.

Question 9

Which of the following best explains why vaccines are effective in preventing infectious diseases?

Accepted Answer

Vaccines artificially introduce antigens, stimulating the adaptive immune response and memory cell formation for long-term protection.

Question 10

A patient with type 1 diabetes has immune cells attacking insulin-producing cells in the pancreas. This is an example of:

Accepted Answer

An autoimmune disease, where the immune system loses tolerance for self.

Question 11

Which of the following is a correct sequence of events in the activation of a B cell during the humoral immune response?

Accepted Answer

Antigen binds to B cell receptor → B cell presents antigen fragment via MHC → Helper T cell activates B cell → B cell proliferates and secretes antibodies.

Question 12

Which class of immunoglobulin (Ig) is membrane-bound on B cells, while the other four classes are soluble?

Accepted Answer

IgD

Question 13

What is the main function of cytotoxic T cells in the immune response?

Accepted Answer

To use toxic proteins to kill cells infected by viruses or other intracellular pathogens.

Question 14

Which of the following best describes the complement system?

Accepted Answer

A cascade of about 30 proteins in blood plasma that, when activated by pathogen surfaces, leads to cell lysis and supports both innate and adaptive immunity.

Question 15

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

Accepted Answer

Adaptive immunity is enhanced by previous exposure to a pathogen and involves highly specific receptors.

Question 16

A person exposed to the influenza virus for the first time develops symptoms after several days. Upon re-exposure years later, the immune response is much faster and stronger. This is due to:

Accepted Answer

Immunological memory from memory B and T cells formed during the primary response.

Question 17

Which of the following scenarios best illustrates the concept of self-tolerance in the immune system?

Accepted Answer

B and T cells with receptors specific for self molecules are destroyed or rendered nonfunctional during maturation.

Question 18

Which of the following is a plausible consequence of chronic inflammation, such as that seen in Crohn's disease or ulcerative colitis?

Accepted Answer

Disruption of normal intestinal function and debilitating symptoms.

Question 19

Which equation best represents the number of possible light chain combinations in B cell receptors, given 40 V segments and 5 J segments?

Accepted Answer

$$40 	imes 5 = 200$$

Chapter 43: The Immune System – Innate and Adaptive Immunity

Study Guide - Practice Questions

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