Question 1

Which pair is most appropriately matched?

Accepted Answer

The answer of Which pair is most appropriately matched?
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Question 2

Which class of antibodies is the first released by B cells during a primary immune response?

Accepted Answer

IgM is the first class of antibodies released by B cells during a primary immune response. It is a pentameric antibody that serves as an important component of the innate immune response by neutralizing pathogens and activating complement. Other antibody classes (IgG, IgD, IgA, IgE) are produced later in the immune response.

Question 3

Choose the incorrect pairing between a structural component of an immunoglobulin and its function.

Accepted Answer

The variable regions of light and heavy chains form the antigen binding site, not the antigenic determinants. Antigenic determinants, or epitopes, are parts of the antigen that are recognized by the antigen binding site of the antibody.

Question 4

The extraordinary diversity of antibodies results in part from

Accepted Answer

Antibodies are produced by B cells, which undergo rearrangement of genes during their development to create unique antibody molecules. This process, known as V(D)J recombination, allows for the creation of a vast repertoire of different antibodies with different specificities.

Question 5

Which statement is correct?

Accepted Answer

The variable region of a light chain and the variable region of a heavy chain form an antigen binding site of an immunoglobulin. Each immunoglobulin molecule has two identical antigen binding sites.

Answer: C
 Antibodies are trivalent, meaning they have three identical binding sites for antigens.

Answer: E
 This statement is false. Antibodies can bind to multiple antigen molecules at once, forming large complexes.

Question 6

Antibody specificity results from the

Accepted Answer

Antibody specificity is primarily determined by the amino acid sequences of the variable regions within the binding site of the antibody molecule. These variable regions are responsible for recognizing and binding to specific antigens. The other options do not directly affect antibody specificity.

Question 7

Which characterizes antibodies in the class IgA?

Accepted Answer

Antibodies in the class IgA prevent attachment of pathogens to epithelial cells of mucous membranes.

Answer: A, C, D, and E are incorrect.
 Antibodies in the class IgA are found primarily in body secretions such as saliva, tears, and breast milk. They have a dimer structure, not monomer, and do not specifically protect epidermal cells of the skin. They also do not bind to mast cells.

Question 8

Which statement about antibodies in the class IgE is true?

Accepted Answer

IgE antibodies bind to basophils and mast cells, which triggers the release of histamine. This process can result in allergic reactions and inflammation. The other choices are not true for IgE antibodies.

Question 9

HIV targets CD4-expressing T cells.One of the long-term results of this is

Accepted Answer

HIV targeting CD4-expressing T cells leads to a compromised immune system, affecting the ability of B cells to produce memory B cells, as these cells rely on signals from T-helper cells (which are depleted by HIV) for their activation and differentiation.

Question 10

With reference to immunoglobulins, a supergene is

Accepted Answer

A supergene is an assemblage of genes encoding a single protein, each of which is selected from a cluster of similar genes. In the case of immunoglobulins, a supergene refers to the cluster of genes encoding the variable and constant regions of the heavy and light chains.

Question 11

If you were to design a vaccine to prevent infection from a mucosal pathogen such as Vibrio cholerae, which antibody class do you think would be most effective in preventing colonization in the intestinal tract?

Accepted Answer

IgA is the most effective antibody class in preventing colonization by mucosal pathogens. It is secreted at mucosal surfaces such as the intestinal tract, where it prevents pathogens from attaching and colonizing. IgA also acts as a neutralizing antibody, preventing pathogens from causing harm to host cells. IgG, IgM, IgD, and IgE are less effective in preventing mucosal infections.

Question 12

Which statement about antibodies in the class IgG is true?

Accepted Answer

IgG antibodies are the most abundant immunoglobulin in the blood and are able to cross the placenta and provide passive immunity to the fetus.

Question 13

Which class of antibodies is critical in the activation of B cells?

Accepted Answer

The answer of Which class of antibodies is critical in...

Question 14

Which statement about class switching is true?

Accepted Answer

Class switching involves a DNA deletion in the constant region of the immunoglobulin gene which results in a different function of the immunoglobulin. The class of the new immunoglobulin is determined by the constant region that is switched to, not by which variable region gene is deleted. Class switching does not affect the antigen specificity of the immunoglobulin. Therefore, option B is the correct choice.

Question 15

Class switching

Accepted Answer

Class switching, also known as isotype switching, refers to a B cell changing the immunoglobulin (Ig) class it synthesizes, while retaining the same antigen specificity. This allows the immune system to produce different classes of antibodies with distinct functions.

Question 16

Which is the least likely use for a monoclonal antibody?

Accepted Answer

Monoclonal antibodies are specific and can be engineered to bind to a wide range of targets, including proteins, cells, and other molecules. They have been used for a variety of applications, including detecting specific proteins on a cell membrane (A), triggering an immune response to cancer cells (C), detecting pregnancy (D), and treating cancer (E). However, monoclonal antibodies are not typically used as vaccines (B). Vaccines usually consist of weakened or dead pathogens or parts of pathogens to stimulate the immune system to produce antibodies against them.

Question 17

Which event does not occur during formation of the heavy chain of an antibody?

Accepted Answer

Formation of the heavy chain of an antibody does not involve the assembly of supergenes by splicing of individual genes of the heavy chains with that of light chains. This is a process that occurs during assembly of the entire antibody molecule, not specifically during heavy chain formation.

Question 18

Which statement about immunoglobulins is true?

Accepted Answer

Immunoglobulin chains are composed of domains, each encoded by different genes selected from a set of similar genes, allowing for the diverse range of antibodies produced by the immune system.

Question 19

A researcher is investigating which time of year birds are exposed to the West Nile Virus (WNV), so she places a cage full of lab-reared (and therefore unexposed) birds near a marsh full of mosquitoes suspected of carrying WNV.Her lab technician tests the birds' blood for anti-WNV antibodies three times per year.Eventually they find a large amount of IgG but almost no IgM.Which is the best conclusion the researcher can reach from these data?

Accepted Answer

IgM is typically the first type of antibody produced in response to an infection, before the body switches to producing IgG. The presence of IgG but almost no IgM suggests that the initial IgM response was missed, indicating that sampling was not frequent enough to capture this early response phase.

Question 20

Which statement about antibodies is correct?

Accepted Answer

Monoclonal antibodies can be produced artificially and used for diagnostic purposes. This statement is true. The other statements are false. A) An antigen can have multiple epitopes. B) Most antigens have multiple antigenic determinants recognized by different antibodies made by different clones of B cells. C) A monoclonal antibody is specific for a single epitope. D) The specificity of antibodies makes them useful in scientific experiments.

Quiz 41: Immunology: Animal Defense Systems