Question 1

Which of the following best describes the main difference between humoral and cell-mediated immunity?

Accepted Answer

Humoral immunity involves B cells and the production of antibodies, while cell-mediated immunity involves T cells and the direct killing of infected cells.

Question 2

A patient receives an injection of pre-formed antibodies against tetanus toxin after stepping on a rusty nail. Which type of acquired immunity is this?

Accepted Answer

Artificially acquired passive immunity

Question 3

Which of the following statements about antigens is CORRECT?

Accepted Answer

Antigens are typically large macromolecules such as proteins or polysaccharides that can trigger an immune response.

Question 4

Which part of the antibody molecule is responsible for binding to antigens?

Accepted Answer

The variable regions of both the heavy and light chains

Question 5

A hapten can only elicit an immune response when:

Accepted Answer

It is attached to a larger carrier molecule

Question 6

Which class of antibody is most effective at agglutinating pathogens due to its pentameric structure and high valency?

Accepted Answer

IgM

Question 7

During a secondary humoral immune response, which antibody is produced in the greatest quantity and with the highest affinity?

Accepted Answer

IgG

Question 8

Which of the following best explains the purpose of clonal deletion during B cell development?

Accepted Answer

To eliminate B cells that recognize self-antigens and prevent autoimmunity

Question 9

A child recovers from chickenpox and is protected from reinfection for many years. This is an example of:

Accepted Answer

Naturally acquired active immunity

Question 10

Which of the following is TRUE regarding T-dependent and T-independent antigens?

Accepted Answer

T-dependent antigens require help from T helper cells for B cell activation, while T-independent antigens can activate B cells without T cell help.

Question 11

Which of the following best describes the role of the Fc region of an antibody?

Accepted Answer

It binds to Fc receptors on phagocytes and mediates effector functions such as opsonization.

Question 12

Which of the following is a function of cytotoxic T (TC) cells?

Accepted Answer

They recognize antigen presented by MHC I molecules and induce apoptosis in infected or abnormal cells.

Question 13

Which of the following cell types is considered a professional antigen-presenting cell (APC)?

Accepted Answer

Dendritic cell

Question 14

A patient with a genetic defect in MHC II expression would have the most difficulty with which of the following immune functions?

Accepted Answer

Activation of CD4+ T helper cells

Question 15

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

Accepted Answer

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

Question 16

Which of the following is a key difference between B and T lymphocytes?

Accepted Answer

B cells recognize free antigens, while T cells recognize antigens only when presented by MHC molecules.

Question 17

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

Accepted Answer

They are signaling proteins that regulate the intensity and duration of immune responses.

Question 18

Natural killer (NK) cells differ from cytotoxic T cells in that NK cells:

Accepted Answer

Do not require antigen presentation by MHC molecules to recognize and kill target cells.

Question 19

A booster immunization is given to a patient several years after the initial vaccination. Which of the following best explains the immunological basis for this practice?

Accepted Answer

It stimulates memory B cells to produce a rapid and robust secondary antibody response.

Question 20

Which of the following equations best represents the valency ($$v) of an $$antibody, and what is the valency of IgM?

Accepted Answer

$$v = 	ext{number of antigen-binding sites}$$; IgM has $$v = 10$$

The Adaptive Immune Response: Humoral and Cell-Mediated Immunity

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