Question 1

Which of the following best describes the primary function of the innate immune system?

Accepted Answer

It provides a rapid, nonspecific response to pathogens using barriers and internal defenses.

Question 2

A patient receives an organ transplant and experiences rejection due to differences in MHC proteins. Which statement best explains this phenomenon?

Accepted Answer

The recipient's immune system recognizes the donor organ as 'non-self' due to different MHC self-antigens.

Question 3

Which of the following is NOT a cardinal sign of inflammation?

Accepted Answer

Fever

Question 4

Which immune cell is primarily responsible for killing virus-infected or cancerous cells by detecting a lack of MHC class I molecules?

Accepted Answer

Natural Killer (NK) cells

Question 5

A child is born with Severe Combined Immunodeficiency (SCID). Which of the following best describes their immune system?

Accepted Answer

They lack functional B and T cells, making them highly susceptible to infections.

Question 6

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

Accepted Answer

IgG

Question 7

What is the main role of interferons in the immune response?

Accepted Answer

They alert neighboring cells to activate antiviral defenses and inhibit viral replication.

Question 8

Which process describes the coating of a pathogen by antibodies or complement proteins to enhance phagocytosis?

Accepted Answer

Opsonization

Question 9

A person is exposed to an allergen for the second time and experiences an allergic reaction. Which immunoglobulin and cell type are primarily involved?

Accepted Answer

IgE and mast cells

Question 10

Which of the following best explains why memory B cells provide a faster and stronger response upon re-exposure to the same antigen?

Accepted Answer

Memory B cells rapidly proliferate and differentiate into plasma cells, producing large amounts of antibodies within 2-3 days.

Question 11

Which of the following is TRUE regarding the difference between MHC class I and MHC class II proteins?

Accepted Answer

MHC class I proteins are found on all nucleated cells, while MHC class II proteins are found only on antigen-presenting cells.

Question 12

Which of the following best describes the process of positive selection during T cell maturation?

Accepted Answer

T cells that recognize self-MHC proteins survive; those that do not undergo apoptosis.

Question 13

A patient with lupus produces antibodies against their own DNA. This is an example of:

Accepted Answer

An autoimmune disease caused by loss of self-tolerance.

Question 14

Which of the following is a key difference between humoral and cell-mediated immunity?

Accepted Answer

Humoral immunity involves B cells and antibodies, while cell-mediated immunity involves T cells acting directly on infected cells.

Question 15

Which of the following equations best represents the relationship between antigen exposure and antibody production during the primary and secondary immune responses?

Accepted Answer

$$A_{secondary} \u003e A_{primary}$$, where $$A is $$the amount of antibody produced$

Question 16

Which of the following best describes the mechanism by which cytotoxic T cells destroy infected cells?

Accepted Answer

They release perforin and granzymes, inducing apoptosis in the target cell.

Question 17

Which of the following is a function of complement proteins in the immune response?

Accepted Answer

They form membrane attack complexes that lyse bacteria.

Question 18

A person receives an injection of antibodies after being exposed to rabies. This is an example of:

Accepted Answer

Artificially acquired passive humoral immunity

Question 19

Which of the following best explains why fever can be beneficial during an infection?

Accepted Answer

Fever inhibits bacterial growth and enhances immune system function.

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

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