Question 1

Which of the following best describes the primary difference between humoral and cellular immunity?

Accepted Answer

Humoral immunity targets extracellular pathogens using antibodies, while cellular immunity targets intracellular pathogens using T cells.

Question 2

A patient receives an injection of preformed antibodies after exposure to a toxin. Which type of adaptive immunity is this?

Accepted Answer

Artificially acquired passive immunity

Question 3

Which immunoglobulin class is most abundant in serum and can cross the placenta to protect the fetus?

Accepted Answer

IgG

Question 4

A child is exposed to chickenpox for the first time and develops the disease. Which immune response is primarily responsible for fighting the infection during this first exposure?

Accepted Answer

Primary response with initial IgM production

Question 5

Which of the following is a function of cytokines in the immune system?

Accepted Answer

They serve as protein messengers that regulate immune cell communication and activity.

Question 6

What is the role of MHC class I molecules in adaptive immunity?

Accepted Answer

They present endogenous antigens to cytotoxic T cells (CD8+).

Question 7

Which process ensures that B cells producing antibodies against self-antigens are eliminated during development?

Accepted Answer

Clonal deletion

Question 8

A laboratory test detects high levels of IgM but low levels of IgG in a patient's serum. What does this most likely indicate?

Accepted Answer

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

Question 9

Which of the following best explains why IgA is important in mucosal immunity?

Accepted Answer

IgA is secreted in dimeric form and prevents microbial attachment to mucous membranes.

Question 10

Which of the following is a correct sequence of events in the activation of a B cell by a T-dependent antigen?

Accepted Answer

Antigen binds BCR → B cell internalizes antigen → Antigen presented on MHC II → Helper T cell recognizes antigen → Cytokines activate B cell

Question 11

Which of the following is a real-life example of antibody-dependent cell-mediated cytotoxicity (ADCC)?

Accepted Answer

A large parasitic worm is coated with antibodies and attacked by eosinophils and NK cells.

Question 12

Which immunoglobulin class is primarily responsible for allergic reactions and defense against parasitic worms?

Accepted Answer

IgE

Question 13

A mutation prevents the production of perforin in cytotoxic T lymphocytes (CTLs). Which immune process would be most directly affected?

Accepted Answer

Lysis of virus-infected cells

Question 14

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

Accepted Answer

They enable a faster and stronger secondary immune response upon re-exposure to the same antigen.

Question 15

Which of the following is NOT a result of antigen–antibody binding?

Accepted Answer

Direct lysis of bacteria by antibodies alone

Question 16

A patient with a genetic defect lacks MHC class II molecules. Which immune function would be most impaired?

Accepted Answer

Activation of helper T cells

Question 17

Which of the following best explains why a cytokine storm can be dangerous to the host?

Accepted Answer

It leads to excessive immune cell activation and widespread inflammation, potentially causing tissue damage.

Question 18

Which of the following statements about haptens is correct?

Accepted Answer

Haptens must bind to a carrier molecule to become antigenic.

Question 19

Which of the following best describes the process of class switching in B cells?

Accepted Answer

A B cell switches from producing IgM to producing another antibody class such as IgG, IgA, or IgE.

Adaptive Immunity: Specific Defenses of the Host

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