Question 1

Antibody molecules circulate in lymph, blood, and tissue fluids.

Accepted Answer

Antibody molecules are produced by B cells and then circulate in lymph, blood, and tissue fluids, where they can recognize and bind to specific antigens.

Question 2

The secondary response to an antigen is faster and bigger than the primary response.

Accepted Answer

The secondary response benefits from the memory B and T cells generated during the primary response, leading to a faster and stronger immune response.

Question 3

B cell-receptors differ from T cell-receptors in that ________.

Accepted Answer

A) B cell receptors (BCRs) are indeed made up of four polypeptides (two heavy chains and two light chains), forming a Y-shaped molecule, while T cell receptors (TCRs) consist of two polypeptide chains. B) BCRs are membrane-bound forms of immunoglobulins that can be secreted upon activation, whereas TCRs are not immunoglobulins and are never secreted. C) TCRs are generally smaller than BCRs due to their simpler two-chain structure compared to the larger, more complex structure of BCRs. Thus, all the choices accurately reflect differences between B cell and T cell receptors.

Question 4

One plasma cell will secrete antibodies of various classes but the antibodies will all have the same specificity.

Accepted Answer

Plasma cells are a type of B cells that produce and secrete large quantities of antibodies specific for a particular antigen. Each plasma cell can only produce antibodies of a single specificity, but the antibodies can belong to different classes such as IgM, IgG, IgA, IgE, or IgD. Therefore, one plasma cell secretes antibodies of the same specificity but different classes.

Question 5

Gamma globulin can be given as immunotherapy to confer artificial passive immunity.

Accepted Answer

Gamma globulin contains immunoglobulins, which can provide short-term protection against certain infections and confer artificial passive immunity.

Question 6

Which of the following statements is false regarding the development of specific immunity?

Accepted Answer

The fourth stage of specific immunity involves the production of antibodies by B cells against the antigen that initiated the response, but T cells do not produce antibodies. Instead, they aid in the response by either directly killing infected cells or by activating B cells to produce antibodies.

Question 7

Which statement is true regarding lymphocyte specificity?

Accepted Answer

Genetic rearrangement in the DNA that codes for antigen receptors results in up to 10 trillion permutations in the variable regions of B- and T lymphocyte-receptors, allowing for a vast number of specificities. There is not a different gene for every possible antigen, and both B- and T cell-receptors can recognize a large number of antigens.

Question 8

The diversity and specificity of the lymphocyte repertoire against any potential antigen it may encounter is due to the rearrangement of gene segments that code for the antigen receptors.

Accepted Answer

This statement is true. The process of gene rearrangement allows for a vast variety of antigen receptors to be produced, which increases the ability of the immune system to recognize and respond to diverse pathogens.

Question 9

B cell-receptors are similar to T cell-receptors in that ________.

Accepted Answer

Both B cell-receptors and T cell-receptors have a variable and a constant region. While some of the other choices may be true for one or the other receptor, only choice B specifically applies to both B cell- and T cell-receptors.

Question 10

Antibodies directed to alloantigen from one organism often cross-react with an alloantigen from another organism.

Accepted Answer

Antibodies are often cross-reactive between alloantigens of different organisms, particularly if they share structural similarities. This can lead to complications in transplantation and blood transfusion, as pre-existing antibodies can recognize and attack foreign tissue or blood products.

Question 11

Human B lymphocytes mature in an intestinal region called the bursa.

Accepted Answer

B lymphocytes mature in the bone marrow, not in the bursa.

Question 12

The structural and functional differences that distinguish immunoglobulin isotypes are due to variations associated with their Fc fragments.

Accepted Answer

This statement is true. The Fc fragment of an immunoglobulin is responsible for its effector functions, such as binding to complement or Fc receptors. Differences in the amino acid sequence and glycosylation of the Fc region contribute to the varying effector functions of different immunoglobulin isotypes.

Question 13

The third line of defense can be summarized in four stages; I-antigen binding to T helper cells, II-antigen binding to B cells, III-phagocytosis of antigen by B and T lymphocytes, IV-killing of antigen.

Accepted Answer

The third line of defense can be summarized in three stages, not four. The stages are: I-antigen binding to T helper cells, II-antigen binding to B cells, III-phagocytosis of antigen by B and T lymphocytes, and activation of cytotoxic T cells to kill the antigen.

Question 14

The hinge region of an antibody has a hypervariable amino acid region where the antigenic determinant fits.

Accepted Answer

The hypervariable regions, also known as complementarity-determining regions (CDRs), are found in the variable domains of both the heavy and light chains of antibodies, not in the hinge region. The hinge region provides flexibility, allowing the variable regions to adapt to different antigens.

Question 15

During which response to the antigen do we display a latent period of no secretory antibody synthesis?

Accepted Answer

During the primary response to an antigen, there is a latent period of no secretory antibody synthesis because the immune system is encountering the antigen for the first time and needs to activate B cells and T cells to initiate a response. This process can take several days.

Question 16

Which of the statements below represents the correct order in the development of an immune response?

Accepted Answer

The correct sequence for the development of an immune response starts with the development and clonal deletion of lymphocytes, ensuring self-reactive cells are eliminated. Next, antigen presentation occurs where antigens are displayed to lymphocytes. This is followed by the lymphocyte challenge, where lymphocytes recognize the antigen, and finally, the lymphocyte response, where the immune response is carried out.

Question 17

After secreting antibodies during an immune response, plasma cells then differentiate into memory cells.

Accepted Answer

Plasma cells are already differentiated cells that produce antibodies during an immune response. Memory cells are formed from activated B cells, not from plasma cells.

Question 18

A naive B lymphocyte has receptors bound to its surface that ________.

Accepted Answer

All of the choices are true statements concerning B lymphocyte-receptors. Naive B lymphocytes have receptors with variable regions that differ from other B cell-receptors, can have up to 10 trillion different protein configurations due to genetic rearrangement, and will secrete antibodies with the same variable region as the B cell-receptor following exposure to the corresponding antigen.

Question 19

Activation of B cells occurs when antigen binds to B-cell surface immunoglobulin receptors.

Accepted Answer

This is true. Activation of B cells occurs when antigens bind to B-cell surface immunoglobulin receptors, which then triggers a series of events leading to B cell proliferation and the production of antibodies.

Question 20

Clonal selection can be stimulated by foreign or self antigens.

Accepted Answer

Clonal selection can be stimulated by both foreign and self antigens. However, self antigens are usually ignored by the immune system to prevent autoimmunity. Exceptions occur when self-tolerance mechanisms fail, leading to autoimmune diseases.

Quiz 13: Host Defenses Ii: Specific Immunity and Immunization