CHAPTER 5: Antibody structure and function

Question 1

Which of the following is characteristic of variable domains of immunoglobulins?
a. They occur on both the H and L chains.
b. They represent the complement-binding site.
c. They are at the carboxy-terminal ends of the molecules.
d. They are found only on H chains.

Answer 1

a. They occur on both the H and L chains.

Question 2

All of the following are true of IgM except that it
a. can cross the placenta.
b. fixes complement.
c. has a J chain.
d. is a primary response antibody.

Answer 2

a. can cross the placenta.

Question 3

How does the structure of IgE differ from that of IgG?
a. IgG has a secretory component and IgE does not.
b. IgE has one more constant region than IgG.
c. IgG has more antigen-binding sites than IgE.
d. IgG has more light chains than IgE.

Answer 3

b. IgE has one more constant region than IgG.

Question 4

How many antigen-binding sites does a typical IgM molecule have?
a. 2
b. 4
c. 6
d. 10

Answer 4

d. 10

Question 5

Bence Jones proteins are identical to which of the following?
a. H chains
b. L chains
c. IgM molecules
d. IgG molecules

Answer 5

b. L chains

Question 6

A Fab fragment consists of
a. two H chains.
b. two L chains.
c. one L chain and one-half of an H chain.
d. one L chain and an entire H chain.

Answer 6

c. one L chain and one-half of an H chain.

Question 7

Which antibody best protects mucosal surfaces?
a. IgA
b. IgG
c. IgD
d. IgM

Answer 7

a. IgA

Question 8

Which of the following pairs represents two different immunoglobulin allotypes?
a. IgM and IgG
b. IgM1 and IgM2
c. Anti-human IgM and anti-human IgG
d. IgG1m3 and IgG1m17

Answer 8

d. IgG1m3 and IgG1m17

Question 9

The structure of a typical immunoglobulin consists of which of the following?
a. 2L and 2H chains
b. 4L and 2H chains
c. 4L and 4H chains
d. 2L and 4 H chains

Answer 9

a. 2L and 2H chains

Question 10

Which of the following are L chains of antibody molecules?
a. Kappa
b. Gamma
c. Mu
d. Alpha

Answer 10

a. Kappa

Question 11

If the results of serum protein electrophoresis show a significant decrease in the gamma band, which of the following is a likely possibility?
a. Normal response to active infection
b. Multiple myeloma
c. Immunodeficiency disorder
d. Monoclonal gammopathy

Answer 11

c. Immunodeficiency disorder

Question 12

The subclasses of IgG differ mainly in
a. the type of L chain.
b. the arrangement of disulfide bonds.
c. the ability to act as opsonins.
d. molecular weight.

Answer 12

b. the arrangement of disulfide bonds.

Question 13

Which best describes the role of the secretory component of IgA?
a. A transport mechanism across endothelial cells
b. A means of joining two IgA monomers together
c. An aid to trapping antigen
d. Enhancement of complement fixation by the classical pathway

Answer 13

a. A transport mechanism across endothelial cells

Question 14

Which represents the main function of IgD?
a. Protection of the mucous membranes
b. Removal of antigens by complement fixation
c. Enhancing proliferation of B cells
d. Destruction of parasitic worms

Answer 14

c. Enhancing proliferation of B cells

Question 15

Which antibody is best at agglutination and complement fixation?
a. IgA
b. IgG
c. IgD
d. IgM

Answer 15

d. IgM

Question 16

Which of the following can be attributed to the clonal selection hypothesis of antibody formation?
a. Plasma cells make generalized antibody.
b. B cells are preprogrammed for specific antibody synthesis.
c. Proteins can alter their shape to conform to antigen.
d. Cell receptors break off and become circulating antibody.

Answer 16

b. B cells are preprogrammed for specific antibody synthesis.

Question 17

All of the following are true of IgE except that it
a. fails to fix complement.
b. is heat stable.
c. attaches to tissue mast cells.
d. is found in the serum of allergic persons.

Answer 17

b. is heat stable.

Question 18

Which best describes coding for immunoglobulin molecules?
a. All genes are located on the same chromosome.
b. L chain rearrangement occurs before H chain rearrangement.
c. Four different regions are involved in coding of H chains.
d. Lambda rearrangement occurs before kappa rearrangement.

Answer 18

c. Four different regions are involved in coding of H chains.

Question 19

What is the purpose of HAT medium in the preparation of monoclonal antibody?
a. Fusion of the two cell types
b. Restricting the growth of myeloma cells
c. Restricting the growth of spleen cells
d. Restricting antibody production to the IgM class

Answer 19

b. Restricting the growth of myeloma cells

Question 20

Papain digestion of an IgG molecule results in which of the following?
a. 2 Fab’ and 1 Fc’ fragment
b. F(ab’)2 and 1 Fc’ fragment
c. 2 Fab and 2 Fc fragments
d. 2 Fab and 1 Fc fragment

Answer 20

d. 2 Fab and 1 Fc fragment

Question 21

Which antibody provides protection to the growing fetus because it is able to cross the placenta?
a. IgG
b. IgA
c. IgM
d. IgD

Answer 21

a. IgG

Question 22

Which best characterizes the secondary response?
a. Equal amounts of IgM and IgG are produced.
b. There is an increase in IgM only.
c. There is a large increase in IgG but not IgM.
d. The lag phase is the same as in the primary response.

Answer 22

c. There is a large increase in IgG but not IgM.