Question 1

Complement molecule, C1 complex, will bind to an IgG antibody at the A) V_L portion. B) F(ab')₂ portion. C) C_L portion. D) F_c portion. E) J-chain region.

Accepted Answer

The C1 complex binds to the Fc portion of an IgG antibody, which is represented by option C.

Question 2

A complete T-cell receptor on a helper T cell contains both the antigen-binding receptor molecule and a ________ protein for signal transduction.
A) CD8
B) CD3 complex
C) MHC I
D) MHC II
E) CD28

Accepted Answer

The CD3 complex is required for the transmission of signals from the T-cell receptor into the cell, leading to activation of the T cell. CD8 and MHC I are involved in the recognition of antigens presented on the surface of infected or cancerous cells by cytotoxic T cells. CD28 is a co-stimulatory receptor on T cells that enhances T cell activation. MHC II is involved in antigen presentation to CD4+ helper T cells.

Question 3

The secondary signal needed for T_H0 helper cells to differentiate into either T_H1 cells or T_H2 cells is the cross-link between ________ (on TH0 helper cells) and ________ (on APC cell). A) CD154; CD40 B) MHC I; B7 C) CD4; MHC II D) CD8; MHC I E) CD28; B7

Accepted Answer

CD28 on T_H0 cells interacts with B7 on APCs to provide the necessary costimulatory signal for differentiation into T_H1 or T_H2 cells.

Question 4

A typical antibody molecule has ________ antigen-binding sites.
A) one
B) four
C) five
D) two
E) three

Accepted Answer

A typical antibody molecule has two antigen-binding sites.

Question 5

RAG1 and RAG2 are enzymes that control gene splicing on B-cell antibody genes. Which order are segments worked on in the creation of the heavy-chain gene segment?
A) VD spliced together, then J, then C
B) DJ spliced together, then V
C) VJ spliced together, then D
D) VC spliced together, then D, then J
E) VDJ segments are all spliced together simultaneously.

Accepted Answer

RAG1 and RAG2 enzymes first join the D and J segments, then the V segment is added to the DJ segment. This order is known as VDJ recombination and applies to the heavy-chain gene segment. Therefore, choice B is the correct order in which the segments are worked on in the creation of the heavy-chain gene segment.

Question 6

Anti-Streptococcus antibodies found in the serum of a patient during a primary antibody response differ from the antibodies produced during a secondary response to the same antigen because of
A) VDJ recombination.
B) affinity maturation.
C) class switching.
D) MHC processing.
E) antigen adaptation.

Accepted Answer

During a primary antibody response, the antibodies produced have low affinity and are less specific. However, during a secondary response, the antibodies are produced by memory B cells which have undergone affinity maturation, leading to an increase in both affinity and specificity of the antibodies. VDJ recombination is a process that occurs during B cell development and is not directly related to the production of different antibodies during a primary versus secondary response. Class switching involves the change in the isotype of the antibodies produced and is not directly related to the differences in antibodies produced during a primary versus secondary response. MHC processing and antigen adaptation are not directly related to the differences in antibodies produced during a primary versus secondary response.

Question 7

An example of an antigen that could stimulate naïve B-cell proliferation and differentiation without the help of a T cell would be a(n) ________ molecule from ________.
A) lipopolysaccharide; Proteus vulgaris
B) plasmid DNA; Yersinia pestis
C) protein A; Staphylococcus aureus
D) anthrax toxin; Bacillus anthracis
E) porin protein; Escherichia coli

Accepted Answer

Lipopolysaccharide is a potent stimulator of the immune system and can activate B-cells directly, without the need for T-cell help. Proteus vulgaris is a Gram-negative bacterium that contains lipopolysaccharide in its cell wall. Plasmid DNA, protein A, anthrax toxin, and porin protein are all antigens that require T-cell help to stimulate naïve B-cell proliferation and differentiation.

Question 8

There are ________ polypeptide chains in the typical antibody.
A) 2
B) 12
C) 4
D) 6
E) 8

Accepted Answer

A typical antibody is made up of 4 polypeptide chains: 2 heavy chains and 2 light chains.

Question 9

The antigen-binding receptor expressing hepatitis antigen in an infected liver cell would be
A) TCR.
B) MHC II.
C) MHC I.
D) CD4.
E) CD8.

Accepted Answer

MHC I is responsible for presenting intracellular antigens, such as hepatitis antigens in infected liver cells, to CD8+ T cells. Therefore, the antigen-binding receptor in this scenario would be the CD8 molecule, which is a co-receptor that binds to the MHC I complex.

Question 10

Positive selection in T-cell education refers to
A) T-cell receptors that can bind strongly to self MHC proteins.
B) CD8 receptors that can bind strongly to self MHC proteins.
C) T-cell receptors that can bind weakly to self MHC proteins.
D) CD4 that can bind weakly to self MHC proteins.
E) B-cell receptors that bind weakly to T-cell receptors.

Accepted Answer

Positive selection in T-cell education ensures that T-cell receptors can bind weakly to self MHC proteins, allowing T-cells to recognize self-MHC but not strongly enough to initiate an autoimmune response.

Question 11

A baby will receive ________ class of antibodies from his or her mother before birth through the umbilical cord, and then ________ class of antibodies through the breast milk after birth.
A) IgG; IgA
B) IgM; IgD
C) IgG; IgM
D) IgM; IgA
E) IgE; IgG

Accepted Answer

The correct answer is A because IgG class of antibodies are transferable through the placenta during fetal development and provide passive immunity to the baby against pathogens that the mother was exposed to. After birth, the baby receives IgA class of antibodies through breast milk, which protect the baby's mucosal surfaces against infections. The other choices, IgM, IgD, IgE, are not typically transferred or produced in significant amounts in a baby during the first few months of life.

Question 12

Mycobacteria spp. have evolved a mechanism to evade adaptive immunity by
A) creating autoantibodies against activated T-cell populations.
B) triggering T- and B-cell apoptosis.
C) hiding within red blood cells of the body (similar to malarial infection).
D) inducing the production of anti-inflammatory cytokines (IL-6 and IL-10).
E) producing phagocytic chemorepellants and paralyzing neutrophils.

Accepted Answer

Mycobacteria spp. induce the production of anti-inflammatory cytokines such as IL-6 and IL-10, which dampen the immune response and allow the bacteria to evade adaptive immunity.

Question 13

Bacteremia is a condition in which live bacteria enter the bloodstream, but not the cells of the body. Which form of processing would occur to stimulate a cell-mediated immune response?
A) bacterial peptide transported from cytoplasm to rER for presentation on MHC I
B) endocytosis by APC followed by presentation on MHC II
C) neutrophil phagocytosis with presentation on Fc receptor
D) cytotoxic T-cell endocytosis for presentation on CD8 receptor
E) B-cell capping for presentation on the B-cell receptor

Accepted Answer

Bacteria in the bloodstream would likely be engulfed by antigen-presenting cells (APCs) through endocytosis. The APCs would then process the bacteria and present bacterial peptides on MHC II molecules, which would activate a cell-mediated immune response. Option A is incorrect as presentation on MHC I is involved in activating a cytotoxic T-cell response, which involves the infected cells with intracellular pathogens. Choice C is incorrect as neutrophils are not antigen-presenting cells. Choice D is incorrect as cytotoxic T-cell endocytosis for presentation on CD8 receptor is not a known mechanism to activate a cell-mediated immune response. Choice E is incorrect as B-cell capping is involved in activating a humoral immune response, not a cell-mediated immune response.

Question 14

Chlamydia trachomatis is a bacterial STD that lives intracellularly within human host cells. What immune response would most likely prevail in this infection?
A) more TH2 cells than TH1 cells
B) more TH1 cells than TH2 cells
C) equal ratio of TH1 cells to TH2 cells
D) more B cells than CD8 cells
E) mostly antibodies

Accepted Answer

The answer of Chlamydia trachomatis is a bacterial STD that...

Question 15

The inflammatory antibody of someone undergoing an allergic reaction to cat dander would be found primarily
A) in the lymph nodes.
B) free-floating in the bloodstream.
C) bound to mast cells and basophils.
D) in mucus secretions.
E) attached to T cells.

Accepted Answer

During an allergic reaction to cat dander, the inflammatory antibody immunoglobulin E (IgE) binds to receptors on mast cells and basophils. When IgE encounters the antigen (cat dander), it triggers the release of inflammatory mediators like histamine, leading to symptoms such as hives, itching, and swelling. Therefore, the IgE antibody would primarily be found bound to mast cells and basophils during an allergic reaction to cat dander.

Question 16

Myasthenia gravis is an autoimmune neuromuscular disease characterized by weakness of the skeletal muscles due to antiacetylcholine receptor antibodies. Thymectomy is a successful treatment for this condition in some patients because it
A) removes all autoreactive B cells from the body.
B) primes antigen-presenting cells to reverse their response to self tissue.
C) neutralizes the autoantibodies from the body.
D) produces proteins to bind the autoantibodies before reaching their target.
E) prevents further miseducation of T-cell populations.

Accepted Answer

Thymectomy is effective in treating myasthenia gravis because the thymus gland plays a crucial role in the education of T cells, including the development of self-tolerance. In myasthenia gravis, the thymus gland is often abnormal, and its removal can prevent the further production of autoreactive T cells that help drive the autoimmune response against acetylcholine receptors.

Question 17

Immunization with the childhood DPT (diphtheria, pertussis, and tetanus) vaccine protects against subsequent exposure to tetanus by
A) stopping isotype switching of B cells from IgM to IgA.
B) preloading antigen-presenting cells.
C) stimulating quick inflammation upon future exposure.
D) producing life-spanning antitetanus IgE antibodies.
E) generating tetanus-specific memory B cells.

Accepted Answer

Immunization with the childhood DPT vaccine generates tetanus-specific memory B cells, which provide long-term protection against future exposure to tetanus. These cells can be rapidly activated upon subsequent exposure to tetanus, leading to a quick and effective immune response.

Question 18

During the course of an intestinal infection with Salmonella enteritidis, the B cells undergo class switching. ________ switching is most likely to occur, which is caused by ________ cytokines.
A) IgD to IgE; B-cell
B) IgM to IgA; T-cell
C) IgG to IgM; B-cell
D) IgA to IgG; T-cell
E) IgD to IgM; T-cell

Accepted Answer

During an intestinal infection with Salmonella enteritidis, B cells are likely to undergo class switching from IgM to IgA. This switch is influenced by cytokines produced by T cells, which help in adapting the immune response to better protect mucosal surfaces such as the intestines.

Question 19

Capping of B-cell receptors on the surface of an antigen-exposed B cell immediately causes
A) VDJ gene switching, recombination, and hypermutation.
B) neutrophil phagocytosis of the antigen.
C) complement cascade signaling and antigen destruction.
D) cell-signaling cascade, inducing cell proliferation and differentiation.
E) helper T-cell proliferation and regulatory T-cell differentiation.

Accepted Answer

Capping of B-cell receptors on the surface of an antigen-exposed B cell immediately causes a cell-signaling cascade, inducing cell proliferation and differentiation. This leads to the formation of plasma cells that secrete antibodies against the antigen.

Question 20

The cells involved in shutting down immune responses that help prevent autoimmunity are
A) B cells.
B) TH17.
C) cytokines.
D) Treg cells.
E) mast cells.

Accepted Answer

The answer of The cells involved in shutting down immune...

Quiz 24: The Adaptive Immune Response

Complement molecule, C1 complex, will bind to an IgG antibody at the

A complete T-cell receptor on a helper T cell contains both the antigen-binding receptor molecule and a ________ protein for signal transduction.

The secondary signal needed for T_H0 helper cells to differentiate into either T_H1 cells or T_H2 cells is the cross-link between (on TH0 helper cells) and (on APC cell) .

A typical antibody molecule has ________ antigen-binding sites.

RAG1 and RAG2 are enzymes that control gene splicing on B-cell antibody genes. Which order are segments worked on in the creation of the heavy-chain gene segment?

Anti-Streptococcus antibodies found in the serum of a patient during a primary antibody response differ from the antibodies produced during a secondary response to the same antigen because of

An example of an antigen that could stimulate naïve B-cell proliferation and differentiation without the help of a T cell would be a(n) molecule from .

There are ________ polypeptide chains in the typical antibody.

The antigen-binding receptor expressing hepatitis antigen in an infected liver cell would be

Positive selection in T-cell education refers to

A baby will receive class of antibodies from his or her mother before birth through the umbilical cord, and then class of antibodies through the breast milk after birth.

Mycobacteria spp. have evolved a mechanism to evade adaptive immunity by

Bacteremia is a condition in which live bacteria enter the bloodstream, but not the cells of the body. Which form of processing would occur to stimulate a cell-mediated immune response?

Chlamydia trachomatis is a bacterial STD that lives intracellularly within human host cells. What immune response would most likely prevail in this infection?

The inflammatory antibody of someone undergoing an allergic reaction to cat dander would be found primarily

Myasthenia gravis is an autoimmune neuromuscular disease characterized by weakness of the skeletal muscles due to antiacetylcholine receptor antibodies. Thymectomy is a successful treatment for this condition in some patients because it

Immunization with the childhood DPT (diphtheria, pertussis, and tetanus) vaccine protects against subsequent exposure to tetanus by

During the course of an intestinal infection with Salmonella enteritidis, the B cells undergo class switching. switching is most likely to occur, which is caused by cytokines.

Capping of B-cell receptors on the surface of an antigen-exposed B cell immediately causes

The cells involved in shutting down immune responses that help prevent autoimmunity are