Mastering Biology Ch. 35, 37+: Body Form and Functions

Which of these binds to receptor molecules on the host cell membrane? D A E C B

A

Acquired immunity involves both a humoral immune response and a cell-mediated immune response. To review the definitions of these immune responses. Sort the items into the appropriate bins depending on whether they are involved in the humoral response, the cell-mediated response, or both the humoral and the cell-mediated responses. (If you are not sure what some of the items are, see Hint 2.)

Acquired immunity involves both a humoral immune response and a cell-mediated immune response to a specific antigen in the body. The two responses are not independent of each other, but rather form an interlinking web. B cells are active in the humoral response. Cytotoxic T cells are active in the cell-mediated response. Helper T cells are active in both responses. Antigen receptors embedded in their plasma membranes enable specific B cells and T cells to recognize and bind to a specific antigen or antigen fragment. After encountering an antigen or antigen fragment it recognizes, the lymphocyte becomes activated, triggering a response called clonal selection (sometimes called clonal expansion). Clonal selection produces effector cells and memory cells of the activated lymphocyte. Plasma cells are the effector cells of the humoral response; they secrete antibodies that neutralize or tag the foreign pathogen for destruction. Active cytotoxic T cells are the effector cells of the cell-mediated response; they kill infected cells displaying the antigen. Activated helper T cells stimulate the effector cells of both responses with cytokines. The memory cells produced by clonal selection contribute to immunological memory. Memory B cells, memory cytotoxic T cells, and memory helper T cells increase the speed and effectiveness of the immune response to an antigen the body has encountered before.

How does an antihistamine reduce allergy symptoms? An antihistamine blocks receptors for inflammatory chemicals released from granules within mast cells. An antihistamine kills mast cells, blocking an allergic reaction. An antihistamine binds pollen antigens, preventing them from provoking an allergic reaction.

An antihistamine blocks receptors for inflammatory chemicals released from granules within mast cells.

Which secretion is not a barrier that prevents pathogens from entering the body? Antigens. Mucus. Lysozyme. Ear wax.

Antigens

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 ... macrophages T cells ... B cells macrophages ... B cells and T cells B cells ... plasma cells and memory cells

B cells ... plasma cells and memory cells

Which of these is reverse transcriptase? Question #12 D A E C B

C

Which of these is the viral genome? Question #13 C D E A B

E

True or false? The leukocytes of the innate immune system are B cells, macrophages, and neutrophils. True False

False

_____ interact with the antigen-class II MHC complex presented by macrophages. Cytotoxic T cells Helper T cells Epithelial cells Bacterial cells B cells

Helper T cells

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. It results in effector cells with specificity for a large number of antigens. It enables an animal to counter most pathogens almost instantly the first time they are encountered. It allows for the destruction of antibodies.

It enables a rapid defense against an antigen that has been previously encountered.

How do cells involved in the innate immune response detect the presence of pathogens? Antibodies bind to the pathogens. Leukocytes recognize unique molecules on pathogens. Leukocytes recognize the entire pathogen. Leukocytes recognize the secretions from a pathogen.

Leukocytes recognize unique molecules on pathogens.

Tissues are immunogically "typed" before an organ transplant to make sure that the donor and recipient match as closely as possible in their _____. histamines B cells antibodies T cells MHC (major histocompatibility complex) proteins

MHC (major histocompatibility complex) proteins

Which of the following cells can engulf a pathogen? Platelets. Mast cells. Cytokines. Macrophages.

Macrophages

Cytotoxic T cells are the effector cells in the cell-mediated immune response. The diagram below summarizes the interaction of a cytotoxic T cell and its target cell. Drag the labels to their appropriate locations on the diagram below using the following steps. Drag a pink label to each of the pink targets, indicating the types of cells shown. Then, drag blue labels to the remaining targets. The labels under the cell on the left should describe what happens to that cell at each step. The labels under the cell on the right should describe what happens to that cell at each step. Note that TCR stands for T cell receptor.

Multiple molecules are involved in the activation and action of cytotoxic T cells. A cytotoxic T cell is activated through interaction with antigen-presenting cells and signals from helper T cells. Once a cytotoxic T cell has been activated, it can recognize an infected cell presenting a specific antigen fragment on its surface. The T cell receptor (TCR) recognizes the class I MHC-antigen fragment complex, and the CD8 protein on the cytotoxic T cell binds to the MHC molecule. To kill the infected cell, the cytotoxic T cell secretes perforin and granzymes. Perforin perforates the cell by forming pores, allowing granzymes to enter the cell and break down proteins. This leads to apoptosis, or programmed cell death. Once a cytotoxic T cell has induced apoptosis in a cell, it moves on to attack other infected cells or cancer cells.

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). 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. 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.

Which of the following events occurs first when a wound that breaks the skin has occurred? Macrophages present bacterial proteins as antigens on their plasma membrane. Mast cells secrete chemical messengers to regulate blood flow to the wound. Platelets release proteins that form clots and decrease bleeding. Neutrophils secrete substances that degrade bacterial cell walls.

Platelets release proteins that form clots and decrease bleeding.

Which of the following statements best describes the role of mast cells in the inflammatory response? They release chemicals that dilate blood vessels near the wound site, allowing blood components to enter the region from the bloodstream. They release cytokines to stimulate the release of additional neutrophils and macrophages. They secrete substances that degrade bacterial cell walls and engulf and digest the invaders. They release chemicals that constrict blood vessels at some distance from the wound site.

They release chemicals that dilate blood vessels near the wound site, allowing blood components to enter the region from the bloodstream.

The site of inflammation may become swollen due to the increased numbers of cells and fluids at the site and painful due to signals from pain receptors. True False

True

B cells are involved in the humoral immune response. The flowchart below summarizes the steps involved in B cell activation. Drag the labels to their appropriate locations on the flowchart below. (Note that TCR stands for T cell receptor.)

When a B cell encounters an antigen it recognizes via its antigen receptors, it internalizes part of that antigen and presents a fragment of the antigen with a class II MHC molecule. An activated helper T cell (activated after an encounter with an antigen-presenting cell) can then recognize this class II MHC-antigen fragment complex on the surface of the B cell and bind to it. This interaction, along with cytokines the helper T cell releases, activates the B cell. The B cell then proliferates and differentiates into plasma cells and memory cells. Plasma cells secrete antibodies that neutralize the pathogen or mark it for destruction. Memory B cells aid in the secondary immune response, should the body encounter the same pathogen again.

Clonal selection is an explanation for how _____. HIV (human immunodeficiency virus) can disrupt the immune system V, J, and C gene segments are rearranged macrophages can recognize specific T cells and B cells an antigen can provoke production of high levels of specific antibodies

an antigen can provoke production of high levels of specific antibodies

Extracellular pathogens such as viruses and bacteria in body fluids are attacked by _____. complement proteins helper T cells antibodies from plasma cells antigens cytotoxic T cells

antibodies from plasma cells

The role of active cytotoxic T cells is to attack _____. extracellular viruses and bacteria circulating antibodies body cells that have been infected complement proteins circulating proteins

body cells that have been infected

What is the function of reverse transcriptase? catalyzing the formation of RNA from a DNA template catalyzing the formation of a polypeptide from a RNA template catalyzing the formation of RNA from a polypeptide template catalyzing the formation of DNA from a RNA template catalyzing the formation of DNA from a polypeptide template

catalyzing the formation of DNA from a RNA template

Helper T cells are part of _____. innate immunity a group of phagocytic white blood cells the complement system cell-mediated immune responses the first cells to bind to antigens

cell-mediated immune responses

Innate immunity and acquired immunity are both _____. dependent exclusively on cell-mediated responses characteristics of all vertebrate animals dependent on surface secretions from sebaceous and sweat glands, which give the skin an acidic pH that is unfavorable for bacterial colonization dependent on tears, saliva, and mucous secretions that contain lysozyme, an enzyme that digests bacterial cell walls based on the trapping of microbes by mucus

characteristics of all vertebrate animals

B cells interacting with helper T cells are stimulated to differentiate when _____. cytotoxic T cells present the class II MHC molecule-antigen complex on their surface B cells release cytokines helper T cells release cytokines B cells produce IgE antibodies

helper T cells release cytokines

What is the source of a viral envelope? viral glycoproteins host cell DNA prophages host cell membrane provirus

host cell membrane

Inflammatory responses typically include _____. increased activity of phagocytes in an inflamed area inhibiting the release of white blood cells from bone marrow reduced permeability of blood vessels to conserve plasma release of substances to decrease the blood supply to an inflamed area

increased activity of phagocytes in an inflamed area

Acidity in human sweat is an example of _____. cell-mediated immune responses adaptive immunity innate immunity acquired immunity

innate immunity

An antigen _____. is a foreign molecule that evokes a specific response by a lymphocyte is a protein molecule that helps defend the body against disease could be an invading bacterium induces development of white blood cells in the bone marrow is a protein attacked by an invading microorganism

is a foreign molecule that evokes a specific response by a lymphocyte

Macrophages are _____. the best defense against parasites cells that induce the lysis of virus-infected body cells antigen-presenting cells that originate from neutrophils large, phagocytic cells that can leave the circulation and enter the tissues of the body short-lived cells that self-destruct soon after engulfing foreign invaders

large, phagocytic cells that can leave the circulation and enter the tissues of the body

Vaccination increases the number of _____. epitopes that the immune system can recognize lymphocytes with receptors that can bind to the pathogen major histocompatability (MHC) molecules that can present an antigen macrophages specific for a 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 plasma cell macrophage helper T cell B cell

macrophage

The cells and signaling molecules involved in the initial stages of the inflammatory response are _____. lymphocytes and interferons phagocytes and chemokines dendritic cells and interferons mast cells and histamines

mast cells and histamines

Which of these cells is responsible for the rapidity of the secondary immune response? plasma cells cytokines macrophages memory cells cytotoxic T 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 influenza is a disease that causes the apoptosis of all memory cells the first infection with influenza weakens the immune system

mutation in the influenza virus is frequent

A primary reason for needing a new vaccine for influenza each year is that _____. the influenza virus might proliferate in different tissues during each subsequent year, and immune memory is limited to those tissues initially infected mutation in the influenza virus is frequent immunity typically disappears one month after recovery from a disease 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

Lymphocytes mature in the _____. I) spleen II) thymus III) bone marrow I, II, and III only II and III only I and II only I and III

only II and III

The role of cytotoxic T cells is the secretion of _____, which plays a role in the _____ immune response. perforin ... humoral perforin ... cell-mediated interleukin-2 ... humoral antibodies ... antibody-mediated antibodies ... humoral

perforin ... cell-mediated

B cells that have been stimulated by interleukin-2 develop into _____. antigens cytotoxic T cells helper T cells macrophages plasma cells

plasma cells

Which of these cells produce and secrete antibodies? helper T cells macrophages plasma cells cytotoxic T cells bacterial cells

plasma cells

Double-stranded viral DNA is incorporated into a host cell as a _____. lac transposon promoter homeoboxes provirus

provirus

The fact that there are about a million different antigen receptors possible in human B cells is based on _____. 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 constant changes in the splicing pattern of receptor genes after the differentiation of the B cell the capacity of memory cells to produce antibodies temporary changes in the ways that RNA is spliced in the B cells

recombination of the segments of the receptor DNA that make up the functional receptor genes of differentiated B cells

What enzyme is responsible for the process seen here? endonuclease reverse transcriptase DNA ligase RNA polymerase DNA polymerase

reverse transcriptase

The genetic material of HIV consists of _____. none of the above single-stranded RNA single-stranded DNA double-stranded DNA double-stranded RNA

single-stranded RNA

Immunological memory accounts for _____. 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 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

When antibodies bind antigens, the clumping of antigens results from _____. disulfide bridges between the antigens bonds between class I and class II MHC molecules denaturation of the antibodies the antibody having at least two binding regions

the antibody having at least two binding regions

For the successful development of a vaccine to be used against a pathogen, it is necessary that _____. the major histocompatability (MHC) molecules are heterozygous the pathogen has only one epitope the surface antigens of the pathogen stay the same all of the surface antigens on the pathogen be identified

the surface antigens of the pathogen stay the same

Cell-mediated immunity differs from humoral immunity in that _____. a humoral response is mounted more quickly they respond differently to invaders cell-mediated immunity is longer lasting a subsequent secondary immune response can occur in humoral immunity clonal selection occurs only in cell-mediated immunity

they respond differently to invaders