Chapter 7 Quiz

o How are B cells activated upon antigen recognition?

• By cytokine secretion

• By cross-linking of antigen receptors

• Through direct activation by T cells

• By somatic hypermutation

Answer explanation

B cells are activated by the cross-linking of antigen receptors.

What is the primary antibody secreted by plasma cells after clonal expansion?

• IgE

• IgM

• IgG

• IgA

Answer explanation

The first antibodies secreted by plasma cells are IgM.

Which enzyme is involved in somatic hypermutation, leading to antibody diversity?

• DNA polymerase

• RNA polymerase

• Activation Induced Deaminase (AID)

• Reverse transcriptase

Answer explanation

Activation Induced Deaminase (AID) is involved in somatic hypermutation.

What is required for a T-dependent antibody response?

• Activation by polysaccharides 

• Activation by lipids 

• T cell help via CD40/CD40L interaction

• Binding of CR2 to C3d 

Answer explanation

CD40L induces double-stranded DNA breaks during class switching.

Where does affinity maturation occur?

• Thymus

• Spleen

• Bone marrow

• Germinal centers of lymphoid follicles

Answer explanation

Affinity maturation occurs in the germinal centers of lymphoid follicles.

Which receptor on B cells enhances activation by binding C3d-coated antigens?

• TLR4

• CD21 (CR2)

• CD40

• BCR

Answer explanation

The complement molecule C3d binds to CR2 (CD21) on B cells, activating them.

Which process contributes to the diversity of B cell receptors during clonal expansion?

• Class switching

• Affinity maturation

• Somatic hypermutation

• Isotype switching

Answer explanation

Somatic hypermutation introduces diversity in B cell receptors during clonal expansion

In X-linked hyper-IgM syndrome, what is the consequence of the mutation in the CD40L gene?

• Enhanced antibody production

• Defective class switching

• Increased plasma cell differentiation

• Improved T cell responses

Answer explanation

X-linked hyper-IgM syndrome results in defective class switching due to the mutation in CD40L.

Which process allows antibodies to increase their specificity over time?

• Isotype switching

• BCR cross-linking 

• Complement activation 

• Somatic hypermutation

Answer explanation

The primary effector function of antibody isotypes is neutralization of pathogens

Where do memory B cells primarily reside?

• Lymph nodes

• Blood

• Spleen

• Bone marrow and mucosal tissues

Answer explanation

Memory B cells reside in the bone marrow and mucosal tissues.