Final Exam
Clonal selection is the division of _____ that have been stimulated by binding to an antigen, which results in the production of cloned _____.
B cells ... plasma cells and memory cells
Which of the following pairs of proteins shares the most overall similarity in structure?
B-cell receptors and antibodies
A man who has been exposed to the flu virus is tested by his physician. The physician notes that the virus is present but no measurable level of antibodies corresponding to the virus are detected in his body.
He was probably exposed a few days ago and clonal selection has yet to produce plasma cells.
_____ interact with the antigen-class II MHC complex presented by macrophages.
Helper T cells
Arrange in the correct sequence these components of the mammalian immune system as it first responds to a pathogen. I) Pathogen is destroyed. II) Lymphocytes secrete antibodies. III) Antigenic determinants from pathogen bind to antigen receptors on lymphocytes. IV) Lymphocytes specific to antigenic determinants from pathogen become numerous. V) Only memory cells remain.
III → IV → II → I → V
What major advantage is conveyed by having a system of adaptive immunity?
It enables a rapid defense against an antigen that has been previously encountered.
Tissues are immunogically "typed" before an organ transplant to make sure that the donor and recipient match as closely as possible in their _____.
MHC (major histocompatibility complex) proteins
Which of the following is a difference between B cells and T cells?
One has a major role in antibody production, while the other has a major role in cytotoxicity.
Which is a true statement about memory cells?
They have a longer lifespan than plasma cells.
Clonal selection is an explanation for how _____.
an antigen can provoke production of high levels of specific antibodies
Extracellular pathogens such as viruses and bacteria in body fluids are attacked by _____.
antibodies from plasma cells
A newborn who is accidentally given a drug that destroys the thymus would most likely _____.
be unable to differentiate and mature T cells
The role of active cytotoxic T cells is to attack _____.
body cells that have been infected
Helper T cells are part of _____.
cell-mediated immune responses
An otherwise healthy student in your class is infected with EBV, the virus that causes infectious mononucleosis. The same student had already been infected when she was a child, at which time she had merely experienced a mild sore throat and swollen lymph nodes in her neck. This time, though infected, she does not get sick. The EBV antigen fragments will be presented by the virus-infected cells along with _____.
class I MHC molecules
The words "antigen" and "virus" are interchangeable.
false
An individual who has been bitten by a poisonous snake that has a fast-acting toxin would likely benefit from _____.
injection of antibodies to the toxin
An antigen _____.
is a foreign molecule that evokes a specific response by a lymphocyte
Vaccination increases the number of _____.
lymphocytes with receptors that can bind to the pathogen
Which of these cells is a phagocytic leukocyte that can engulf a foreign bacterium?
macrophage
If a patient is missing B and T cells, what would be absent from the immune response?
memory
A certain cell type has existed in the blood and tissue of its vertebrate host's immune system for over twenty years. One day, it recognizes a newly arrived antigen and binds to it, subsequently triggering a secondary immune response in the body. Which of the following cell types most accurately describes this cell?
memory cell
Which of these cells is responsible for the rapidity of the secondary immune response?
memory cells
An immunoglobulin (Ig) molecule, of whatever class, with regions symbolized as C or V, H or L, has a light chain made up of _____.
one C region and one V region
Which of the following statements about epitopes are correct? I) B-cell receptors bind to epitopes. II) T-cell receptors bind to epitopes. III) There can be 10 or more different epitopes on each antigen. IV) There is a one-to-one correspondence between antigen and epitope.
only I, II, and III
Which of the following statements are fundamental to the clonal-selection theory of how the adaptive immune system functions? I) Each lymphocyte has a unique membrane receptor that recognizes one antigen. II) When the lymphocyte binds an antigen, it is activated and begins dividing to form many identical copies of itself. III) Cloned lymphocytes have slight differences and are selected by the spleen for removal if they do not bind an antigen. IV) Cloned cells descend from an activated lymphocyte and persist even after the pathogen is eliminated.
only I, II, and IV
Lymphocytes mature in the _____. I) spleen II) thymus III) bone marrow
only II and III
What type of immunity is associated with breast feeding?
passive immunity
The role of cytotoxic T cells is the secretion of _____, which plays a role in the _____ immune response.
perforin ... cell-mediated
Naturally acquired passive immunity can result from the _____.
placental transfer of antibodies
B cells that have been stimulated by interleukin-2 develop into _____.
plasma cells
Which of these cells produce and secrete antibodies?
plasma cells
Within a differentiated B cell, the rearrangement of DNA sequences between variable regions and joining regions is accomplished by a(n)_____.
recombinase
The fact that there are about a million different antigen receptors possible in human B cells is based on _____.
recombination of the segments of the receptor DNA that make up the functional receptor genes of differentiated B cells
Clonal selection and differentiation of B cells activated by antigen exposure leads to the production of _____.
short-lived plasma cells that secrete antibodies for the antigen
Immunological memory accounts for _____.
the ancient observation that someone who had recovered from the plague could safely care for those newly diseased
When antibodies bind antigens, the clumping of antigens results from _____.
the antibody having at least two binding regions
The switch of one B cell from producing one class of antibody to another class of antibody that is responsive to the same antigen is due to _____.
the rearrangement of immunoglobulin heavy-chain C region DNA
For the successful development of a vaccine to be used against a pathogen, it is necessary that _____.
the surface antigens of the pathogen stay the same
Jenner's successful use of cowpox virus as a vaccine against the smallpox virus was due to the fact that _____.
there are some epitopes (antigenic determinants) common to both pox viruses
Cell-mediated immunity differs from humoral immunity in that _____.
they respond differently to invaders