CH 43
Select the correct statement about the immune system. All antigen receptors produced by a single B cell or T cell are identical and bind to the same epitope. Antibodies are secreted by T cells. Adaptive immunity is characteristic of invertebrates and vertebrates.
All antigen receptors produced by a single B cell or T cell are identical and bind to the same epitope.
Because antigen receptor genes are randomly rearranged, some immature lymphocytes produce receptors specific for epitopes on the organism's own molecules. Why doesn't the immune system attack these molecules on the body's cells and tissues? Only a very few lymphocytes produce receptors that attack the body's own molecules, so it's not a problem. B and T cells with receptors specific for the body's own molecules are destroyed by apoptosis. The body's cells are immune to such attack.
B and T cells with receptors specific for the body's own molecules are destroyed by apoptosis.
Which of the following pairs of proteins shares the most overall similarity in structure? antibodies and antigens B-cell receptors and T-cell receptors T-cell receptors and antibodies B-cell receptors and antibodies
B-cell receptors and antibodies
What is the role of recombinase in generating lymphocyte diversity? Recombinase splices RNA to produce variable transcripts. Early in B cell development, recombinase links one light-chain V gene segment to one J gene segment. Recombinase combines DNA from human and viral origin.
Early in B cell development, recombinase links one light-chain V gene segment to one J gene segment.
The words "antigen" and "virus" are interchangeable. True False
False
Part complete Which of the following is a difference between B cells and T cells? One binds a receptor called BCR (B-cell receptor), while the other recognizes a receptor called TCR (T-cell receptor). T cells are produced in the thymus and B cells are produced in the bone marrow. One has a major role in antibody production, while the other has a major role in cytotoxicity. B cells are activated by free-floating antigens in the blood or lymph. T cells are activated by membrane-bound antigens.
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? The first time an antigen is encountered, memory cells become plasma cells. They engulf antigens bound by antibodies. They produce antibodies. They have a longer lifespan than plasma cells.
They have a longer lifespan than plasma cells.
Clonal selection is an explanation for how _____. macrophages can recognize specific T cells and B cells V, J, and C gene segments are rearranged an antigen can provoke production of high levels of specific antibodies HIV (human immunodeficiency virus) can disrupt the immune system
an antigen can provoke production of high levels of specific antibodies
Extracellular pathogens such as viruses and bacteria in body fluids are attacked by _____. antigens antibodies from plasma cells cytotoxic T cells helper T cells complement proteins
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 have a reduced number of B cells and be unable to form antibodies lack innate immunity be unable to genetically rearrange antigen receptors
be unable to differentiate and mature T cells
The role of active cytotoxic T cells is to attack _____. complement proteins extracellular viruses and bacteria circulating antibodies circulating proteins body cells that have been infected
body cells that have been infected
Helper T cells are part of _____. View Available Hint(s) innate immunity the complement system a group of phagocytic white blood cells cell-mediated immune responses the first cells to bind to antigens
cell-mediated immune responses
Use the following information to answer the question(s) below. 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 II MHC molecules class I MHC molecules antibodies a complement
class I MHC molecules
Which of the following components of the immune system destroys bacteria in a way similar to an antitank weapon destroying armored military tanks by punching holes in the wall of the bacteria? macrophages complement protein major histocompatibility complex proteins plasma cells
complement protein
An individual who has been bitten by a poisonous snake that has a fast-acting toxin would likely benefit from _____. vaccination with a weakened form of the toxin injection of interferon injection of interleukin-1 injection of antibodies to the toxin
injection of antibodies to the toxin
Vaccination increases the number of _____. epitopes that the immune system can recognize major histocompatability (MHC) molecules that can present an antigen macrophages specific for a pathogen lymphocytes with receptors that can bind to the pathogen
lymphocytes with receptors that can bind to the pathogen
Which of these cells is a phagocytic leukocyte that can engulf a foreign bacterium? cytotoxic T cell macrophage plasma cell helper T cell B cell
macrophage
If a patient is missing B and T cells, what would be absent from the immune response? defense against bacteria lysozymes memory cytokines
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? macrophage plasma cell thyroid cell memory cell
memory cell
Which of these cells is responsible for the rapidity of the secondary immune response? memory cells cytokines macrophages cytotoxic T cells plasma cells
memory cells
A primary reason for needing a new vaccine for influenza each year is that _____. mutation in the influenza virus is frequent immunity typically disappears one month after recovery from a disease the influenza virus might proliferate in different tissues during each subsequent year, and immune memory is limited to those tissues initially infected the first infection with influenza weakens the immune system influenza is a disease that causes the apoptosis of all memory cells
mutation in the influenza virus is frequent
An immunoglobulin (Ig) molecule, of whatever class, with regions symbolized as C or V, H or L, has a light chain made up of _____. three H regions and one L region one H region and one L region one C region and one V region two C regions and two V regions
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 only II and IV only I and III only II, III, and IV
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 II, III, and IV only I, II, and IV only I and III only II and IV
only I, II, and IV
Lymphocytes mature in the _____. I) spleen II) thymus III) bone marrow only I and III only I and II only II and III I, II, and III
only II and III
Clonal selection and differentiation of B cells activated by antigen exposure leads to the production of _____. large quantities of the antigen initially recognized vast numbers of B cells with random antigen-recognition receptors short-lived plasma cells that secrete antibodies for the antigen long-lived erythrocytes that can later secrete antibodies for the antigen
short-lived plasma cells that secrete antibodies for the antigen
Immunological memory accounts for _____. the human body's ability to distinguish self from non-self the ability of a helper T cell to signal B cells via cytokines the ancient observation that someone who had recovered from the plague could safely care for those newly diseased the observation that some strains of the pathogen that causes dengue fever cause more severe disease than others
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 _____. bonds between class I and class II MHC molecules the antibody having at least two binding regions disulfide bridges between the antigens denaturation of the antibodies
the antibody having at least two binding regions
How does an antihistamine reduce allergy symptoms? An antihistamine blocks receptors for inflammatory chemicals released from granules within mast cells. An antihistamine binds pollen antigens, preventing them from provoking an allergic reaction. An antihistamine kills mast cells, blocking an allergic reaction.
An antihistamine blocks receptors for inflammatory chemicals released from granules within mast cells.
Clonal selection is the division of _____ that have been stimulated by binding to an antigen, which results in the production of cloned _____. helper T cells ... plasma cells B cells ... plasma cells and memory cells macrophages ... B cells and T cells T cells ... B cells B cells ... macrophages
B cells ... plasma cells and memory cells
Each person makes more than 1 million different B cell antigen receptors and more than 10 million different T cell antigen receptors. How is such diversity in antigen receptors generated? By combining variable elements, the immune system assembles many different receptors from a much smaller collection of parts. A large percentage of the vertebrate genome is devoted to genes for individual antigen-binding sites. Genes for individual antigen-binding sites have a very high rate of mutation, generating great diversity.
By combining variable elements, the immune system assembles many different receptors from a much smaller collection of parts.
_____ interact with the antigen-class II MHC complex presented by macrophages. Epithelial cells Helper T cells B cells Bacterial cells Cytotoxic T cells
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. II → I → IV → III → V III → IV → II → I → V IV → II → III → I → V I → III → II → IV → V
III → IV → II → I → V
Part complete What major advantage is conveyed by having a system of adaptive immunity? It allows for the destruction of antibodies. It enables a rapid defense against an antigen that has been previously encountered. It enables an animal to counter most pathogens almost instantly the first time they are encountered. It results in effector cells with specificity for a large number of antigens.
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 _____. antibodies MHC (major histocompatibility complex) proteins histamines B cells T cells
MHC (major histocompatibility complex) proteins
An antigen _____. is a foreign molecule that evokes a specific response by a lymphocyte induces development of white blood cells in the bone marrow is a protein molecule that helps defend the body against disease is a protein attacked by an invading microorganism could be an invading bacterium
is a foreign molecule that evokes a specific response by a lymphocyte
What type of immunity is associated with breast feeding? active immunity innate immunity passive immunity cell-mediated immunity
passive immunity
The role of cytotoxic T cells is the secretion of _____, which plays a role in the _____ immune response. perforin ... humoral interleukin-2 ... humoral antibodies ... humoral antibodies ... antibody-mediated perforin ... cell-mediated
perforin ... cell-mediated
Naturally acquired passive immunity can result from the _____. absorption of pathogens through mucous membranes ingestion of interferon placental transfer of antibodies injection of vaccine
placental transfer of antibodies
B cells that have been stimulated by interleukin-2 develop into _____. macrophages helper T cells plasma cells antigens cytoxic T cells
plasma cells
Which of these cells produce and secrete antibodies? plasma cells helper T cells macrophages bacterial cells cytotoxic T cells
plasma cells
Yearly vaccination of humans for influenza viruses is necessary because _____. surviving the flu one year exhausts the immune system to nonresponsiveness the second year of an increase in immunodeficiency diseases rapid mutation in flu viruses alters the surface proteins in infected host cells the flu can generate anaphylactic shock
rapid mutation in flu viruses alters the surface proteins in infected host cells
Within a differentiated B cell, the rearrangement of DNA sequences between variable regions and joining regions is accomplished by a(n)_____. recombinase epitopase RNA polymerase reverse transcriptase
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 the capacity of memory cells to produce antibodies temporary changes in the ways that RNA is spliced in the B cells constant changes in the splicing pattern of receptor genes after the differentiation of the B cell having one million different immunoglobulin genes
recombination of the segments of the receptor DNA that make up the functional receptor genes of differentiated B cells
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 _____. a patient's reaction to the first kind of antibody made by the plasma cells the rearrangement of V region genes in that clone of responsive B cells the rearrangement of immunoglobulin heavy-chain C region DNA a switch in the kind of antigen-presenting cell that is involved in the immune response
the rearrangement of immunoglobulin heavy-chain C region DNA
Which of the following should be the same in identical twins? the set of major histocompatability (MHC) molecules produced the set of antibodies produced the susceptibility to a particular virus the set of T cell antigen receptors produced
the set of major histocompatability (MHC) molecules produced
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 the pathogen has only one epitope the major histocompatability (MHC) molecules are heterozygous all of the surface antigens on the pathogen be identified
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 _____. cowpox and smallpox are caused by the same virus the cowpox virus made antibodies in response to the presence of smallpox there are some epitopes (antigenic determinants) common to both pox viruses the immune system responds nonspecifically to antigens
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 clonal selection occurs only in cell-mediated immunity a humoral response is mounted more quickly a subsequent secondary immune response can occur in humoral immunity cell-mediated immunity is longer lasting
they respond differently to invaders
