Question 1

Which of the following best describes the main difference between B cells and T cells in adaptive immunity?

Accepted Answer

B cells mature in the bone marrow and produce antibodies, while T cells mature in the thymus and kill infected cells.

Question 2

A patient is exposed to a pathogen for the first time. Which antibody class is expected to appear first in their blood, and what is its main function?

Accepted Answer

IgM; agglutination and complement activation

Question 3

Which region of the antibody determines its class (isotype) and how it interacts with other immune cells?

Accepted Answer

Constant (C) region

Question 4

A newborn receives immediate intestinal protection from antibodies in colostrum. Which antibody class is primarily responsible for this protection?

Accepted Answer

IgA

Question 5

Which process allows B cells to change the class of antibody they produce without altering the antigen specificity?

Accepted Answer

Class switching

Question 6

What is the primary role of Helper T cells (CD4+ T cells) in the adaptive immune response?

Accepted Answer

Coordinating the immune response by activating B cells and other immune cells

Question 7

Which of the following best explains why organ transplants are often rejected by the recipient's immune system?

Accepted Answer

The recipient's T cells recognize the donor's MHC molecules as foreign.

Question 8

A patient with HIV/AIDS has a severely reduced number of Helper T cells. Which of the following immune functions would be most directly impaired?

Accepted Answer

Production of high-affinity IgG antibodies and formation of immune memory

Question 9

Which statement best describes the concept of immune memory in adaptive immunity?

Accepted Answer

Memory cells persist for years, enabling a faster and stronger response upon re-exposure to the same pathogen.

Question 10

Which of the following is a unique feature of the Major Histocompatibility Complex (MHC) genes in humans?

Accepted Answer

They are highly polymorphic, increasing the diversity of antigen presentation.

Question 11

A patient experiences allergy symptoms after exposure to pollen. Which antibody class and immune cell interaction is primarily responsible for this reaction?

Accepted Answer

IgE binding to mast cells

Question 12

Which of the following best describes the role of dendritic cells in the adaptive immune response?

Accepted Answer

They capture antigens and present them to T cells, initiating the adaptive response.

Question 13

Which antibody class is most effective at activating the complement system and agglutinating pathogens due to its pentameric structure?

Accepted Answer

IgM

Question 14

Which of the following best explains the concept of MHC restriction?

Accepted Answer

A T cell recognizes an antigen only when presented by a specific self-MHC molecule.

Question 15

Which of the following is a direct result of cytokine release by Helper T cells during the adaptive immune response?

Accepted Answer

Activation and differentiation of B cells into plasma cells

Question 16

A mutation causes a loss of the hinge region in antibodies. Which function would be most affected?

Accepted Answer

Ability to bind antigens at varying distances

Question 17

Which of the following best describes the process of cross-presentation by dendritic cells?

Accepted Answer

Presenting external antigens on MHC Class I to activate Cytotoxic T cells

Question 18

Which antibody class is primarily found on the surface of naïve B cells and acts as a signaling sensor?

Accepted Answer

IgD

Question 19

A patient with a genetic defect in MHC gene expression is likely to experience which of the following?

Accepted Answer

Impaired antigen presentation and increased susceptibility to infections

Question 20

Which of the following equations best represents the relationship between the number of different antibodies ($$N) $$that can be produced and the number of variable regions ($$V$$), diversity regions ($$D$$), and joining regions ($$J) in $$antibody gene recombination?

Accepted Answer

$$N = V 	imes D 	imes J$$

lec 26:Adaptive Immunity: Mechanisms, Components, and Clinical Relevance

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