Q: Which of the following equations correctly calculates the number of possible heavy chain combinations for BCR diversity, given 65 variable segments, 27 diversity segments, and 6 junction segments on two chromosomes?

$$65 \times 27 \times 6 \times 2 = 21060$$

Question 1

Which of the following best describes the primary function of B lymphocytes in adaptive immunity?

Accepted Answer

Secretion of antibodies that bind to specific antigens

Question 2

A patient is exposed to a novel virus. Which process allows their B cells to generate billions of unique B cell receptors (BCRs) despite having only about 25,000 genes?

Accepted Answer

Recombination of variable, diversity, and joining gene segments

Question 3

Which antibody class is most abundant in blood and is able to cross the placenta to provide passive immunity to a fetus?

Accepted Answer

IgG

Question 4

What is the role of the variable region of an antibody?

Accepted Answer

It forms the antigen-binding site and determines specificity for epitopes

Question 5

Which of the following equations correctly calculates the number of possible heavy chain combinations for BCR diversity, given 65 variable segments, 27 diversity segments, and 6 junction segments on two chromosomes?

Accepted Answer

$$65 	imes 27 	imes 6 	imes 2 = 21060$$

Question 6

Which antibody function involves binding to toxins or adhesion proteins on pathogens to prevent their harmful effects?

Accepted Answer

Neutralization

Question 7

A child is infected with a bacterium that has a polysaccharide capsule with repeating epitopes. Which type of antibody response is most likely to be induced?

Accepted Answer

T-independent antibody immunity

Question 8

Which process allows a B cell to produce different classes of antibodies (e.g., switching from IgM to IgG) while maintaining antigen specificity?

Accepted Answer

Class switching, attaching the variable region to a different stem gene

Question 9

Which antibody class is primarily found in body secretions such as saliva, tears, and breast milk, and helps protect mucosal surfaces?

Accepted Answer

IgA

Question 10

What is the outcome of clonal deletion in B cell development?

Accepted Answer

Elimination of B cells that bind to self-antigens

Question 11

Which of the following is a direct result of antibody-dependent cellular cytotoxicity (ADCC)?

Accepted Answer

Lysis of target cells by natural killer (NK) cells

Question 12

During a secondary immune response, which of the following best explains why antibody production is faster and greater than during the primary response?

Accepted Answer

Memory B cells rapidly differentiate into plasma cells upon re-exposure to antigen

Question 13

Which of the following best describes the process of opsonization?

Accepted Answer

Antibodies bind to pathogens and stimulate phagocytosis by marking them for engulfment

Question 14

A plasma cell is characterized by which of the following features compared to a naive B cell?

Accepted Answer

Twice the size and abundant rough ER and Golgi bodies for antibody secretion

Question 15

Which of the following is TRUE regarding the antigen-binding sites of antibodies?

Accepted Answer

They are complementary to the three-dimensional shape of an epitope

Question 16

Which of the following steps is required for T-dependent activation of B cells?

Accepted Answer

Interaction with a helper T cell (Th2) via MHC II and TCR

Question 17

Which antibody class is most involved in allergic reactions and defense against parasitic worms?

Accepted Answer

IgE

Question 18

What is the main difference between plasma cells and memory B cells?

Accepted Answer

Plasma cells secrete antibodies, while memory B cells do not

Question 19

Which of the following best explains why large foreign macromolecules make the best antigens?

Accepted Answer

They contain multiple epitopes that can be recognized by different BCRs

Question 20

Which of the following is NOT a function of antibodies?

Accepted Answer

Direct killing of pathogens by phagocytosis

Adaptive Immunity: The Role of B Cells and Antibodies

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