Question 1

Which of the following best describes the primary site of B-cell development in adult humans?

Accepted Answer

Bone marrow

Question 2

During fetal development, which sequence correctly represents the major sites of hematopoiesis in order?

Accepted Answer

Yolk sac → Aorta-gonad-mesonephros (AGM) → Liver → Bone marrow

Question 3

Which B-cell subtype is primarily responsible for immune surveillance in body cavities and is self-renewing?

Accepted Answer

B-1 B cells

Question 4

A patient has a genetic defect that prevents the expression of the IL-7 receptor on lymphoid progenitor cells. Which stage of B-cell development would be most directly affected?

Accepted Answer

Differentiation from lymphoid-primed multipotent progenitor to common lymphoid progenitor

Question 5

Which of the following events must occur for a pro-B cell to progress to the pre-B cell stage?

Accepted Answer

Productive rearrangement of the immunoglobulin heavy chain locus

Question 6

What is the primary mechanism by which self-reactive immature B cells are eliminated in the bone marrow?

Accepted Answer

Clonal deletion via apoptosis

Question 7

Which of the following best explains why negative selection of B cells in the bone marrow is less stringent than that of T cells in the thymus?

Accepted Answer

B-cell activation requires T-cell help, providing an additional checkpoint for self-tolerance

Question 8

A developing B cell fails to produce a functional light chain after all four rearrangement attempts. What is the most likely fate of this cell?

Accepted Answer

It undergoes clonal deletion (apoptosis)

Question 9

Which of the following cell-surface markers is most characteristic of transitional T2 B cells in the spleen?

Accepted Answer

Low IgM, high IgD, high BAFF-R

Question 10

Which of the following best describes the process of receptor editing in B-cell development?

Accepted Answer

Reactivation of light chain gene rearrangement to change antigen specificity in self-reactive B cells

Question 11

A mutation prevents the expression of RAG1 and RAG2 in developing lymphocytes. Which process would be directly impaired?

Accepted Answer

V(D)J recombination of immunoglobulin genes

Question 12

Which of the following is a critical checkpoint in B-cell development that ensures allelic exclusion?

Accepted Answer

Successful rearrangement and expression of a functional heavy chain

Question 13

Which of the following best describes the fate of mature, naive B cells after they exit the spleen?

Accepted Answer

They circulate through the blood and secondary lymphoid tissues, scanning for antigen

Question 14

Which of the following is true regarding the role of the BAFF receptor (BAFF-R) in B-cell development?

Accepted Answer

It provides survival signals to transitional B cells in the spleen

Question 15

A researcher is studying the effects of a drug that blocks the interaction between c-Kit and stem cell factor (SCF) in the bone marrow. Which process would be most directly affected?

Accepted Answer

Differentiation of hematopoietic stem cells into multipotent progenitor cells

Question 16

Which of the following best explains why B-1 B cells are particularly important during fetal development?

Accepted Answer

They are self-renewing and can respond to pathogens that invade body cavities before birth

Question 17

Which of the following equations best represents the number of possible immunoglobulin heavy chain combinations if there are $$V$$ variable, $$D$$ diversity, and $$J$$ joining gene segments?

Accepted Answer

$$N = V 	imes D 	imes J$$

Question 18

A patient’s B cells are found to express both kappa and lambda light chains on their surface. Which developmental checkpoint likely failed?

Accepted Answer

Allelic exclusion at the light chain locus

Question 19

Which of the following best describes the fate of transitional T1 B cells in the spleen that strongly bind self-antigen?

Accepted Answer

They are eliminated by negative selection via apoptosis

Question 20

Which of the following is a key difference between B-cell and T-cell development regarding antigen receptor diversity?

Accepted Answer

B cells can only produce one functional type of immunoglobulin, while T cells can produce two forms of the T-cell receptor

Development of B Lymphocytes: Structure, Stages, and Selection

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