Question 1

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

Accepted Answer

IgM is the first antibody produced in response to an infection and is effective at agglutinating pathogens.

Question 2

What is the primary function of the variable region of a T-cell receptor?

Accepted Answer

To bind to a specific antigen presented by an antigen-presenting cell.

Question 3

Which process is responsible for the diversity of antigen-binding sites on B-cell and T-cell receptors?

Accepted Answer

Random recombination of gene segments during cell maturation

Question 4

A patient receives a COVID-19 mRNA vaccine. Which sequence of events best describes the immune response?

Accepted Answer

The mRNA is translated into spike protein, which is displayed on the cell surface, activating cytotoxic T-cells and B-cells to produce antibodies.

Question 5

Which of the following statements about IgG is TRUE?

Accepted Answer

IgG is the only antibody class that can cross the placenta and provide immunity to the fetus.

Question 6

What is the main difference between the innate and adaptive immune responses?

Accepted Answer

The innate response provides immediate defense, while the adaptive response is slower but specific to pathogens.

Question 7

Which cell type is responsible for producing antibodies in the adaptive immune response?

Accepted Answer

Plasma cells derived from B-cells

Question 8

During clonal selection in the thymus, what happens to T-cells that strongly bind to self-antigen?

Accepted Answer

They are eliminated to prevent autoimmune disease.

Question 9

Which equation best represents the process of agglutination by antibodies?

Accepted Answer

$$Antibody + Pathogen \rightarrow Antibody{-}Pathogen \ Complex$$

Question 10

Why is the secondary immune response to an antigen exposure faster and stronger than the primary response?

Accepted Answer

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

Question 11

Which of the following is a function of cytotoxic T-cells in the immune response to viral infection?

Accepted Answer

They destroy infected cells by recognizing viral antigens presented on MHC I molecules.

Question 12

What is the role of antigen-presenting cells (APCs) in the activation of T-cells?

Accepted Answer

APCs display processed antigen fragments on MHC molecules to activate T-cells.

Question 13

Which statement best explains why newborns are not protected by IgM antibodies from their mothers?

Accepted Answer

IgM is too large to cross the placenta.

Question 14

Which of the following best describes the mechanism of the Pfizer-BioNTech COVID-19 vaccine?

Accepted Answer

It uses a harmless viral vector to deliver the gene for the spike protein, which is then expressed and presented to the immune system.

Question 15

Which of the following is TRUE about the spike protein of SARS-CoV-2?

Accepted Answer

It is recognized by the immune system as an antigen and binds to ACE-2 receptors on human cells.

Question 16

Which of the following equations best represents the activation of B-cells by T-helper cells?

Accepted Answer

$$B{-}cell_{antigen} + T{-}helper \rightarrow Plasma \ Cell + Antibody$$

Question 17

Which statement best describes the role of memory cells in vaccination?

Accepted Answer

Memory cells enable a rapid and robust immune response upon subsequent exposure to the same antigen.

Question 18

Which of the following is a correct description of the process by which mRNA vaccines work?

Accepted Answer

mRNA vaccines deliver mRNA encoding the spike protein, which is translated by host cells, leading to antigen presentation and immune activation.

Question 19

Which of the following best explains why IgG is important in the secondary immune response?

Accepted Answer

IgG is produced in larger quantities and has a longer half-life, providing sustained immunity upon re-exposure to the antigen.

Immune System and COVID-19 Vaccines: Structure, Function, and Mechanisms

Study Guide - Practice Questions