Chapter 43 mastering Biology

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

provirus

How are cytotoxic T lymphocytes (CTLs) produced? Hints Plasma cells secrete cytotoxic T lymphocytes. Helper T cells divide and differentiate into cytotoxic T lymphocytes. CD8+ T cells divide and differentiate into cytotoxic T lymphocytes. B cells divide and differentiate into cytotoxic T lymphocytes.

CD8+ T cells divide and differentiate into cytotoxic T lymphocytes.

What is the final step in the cell-mediated response to a viral infection? Macrophages digest viral particles. CD8+ T cells are activated. Antibodies coat viral particles. Cytotoxic T lymphocytes punch holes in the membranes of infected host cells.

Cytotoxic T lymphocytes punch holes in the membranes of infected host cells.

The fact that there are about a million different antigen receptors possible in human B cells is based on _____. Hints recombination of the segments of the receptor DNA that make up the functional receptor genes of differentiated B cells temporary changes in the ways that RNA is spliced in the B cells having one million different immunoglobulin genes constant changes in the splicing pattern of receptor genes after the differentiation of the B cell the capacity of memory cells to produce antibodies

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

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. What might this mean? He was probably exposed more than several months ago, antibody production has ceased, and antibodies are no longer detectable. He was probably exposed sometime within the past two weeks, but we don't have enough information to say more. He was probably exposed a few days ago and clonal selection has yet to produce plasma cells.

He was probably exposed a few days ago and clonal selection has yet to produce plasma cells.

How do cells involved in the humoral response respond to antigen presentation on the surface of a B cell? Hints Helper T cells recognize the receptor-antigen complex and cause plasma and memory cells to be produced to then produce antibodies. Helper T cells secrete antibodies against the viral antigen. The B cell recognizes the receptor-antigen complex and divides to produce plasma and memory cells. Helper T cells divide and produce plasma and memory cells.

Helper T cells recognize the receptor-antigen complex and cause plasma and memory cells to be produced to then produce antibodies.

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

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 _____. Hints T cells antibodies MHC (major histocompatibility complex) proteins B cells histamines

MHC (major histocompatibility complex) proteins

Which protein presents viral antigens on the outer surface of cells? Hints B cell receptor. MHC protein. T cell receptor. Antibody.

MHC protein

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

Platelets release proteins that form clots and decrease bleeding.

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

single stranded RNA

Which of the following statements best describes the role of mast cells in the inflammatory response? 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.

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

Which is a true statement about memory cells? They engulf antigens bound by antibodies. They have a longer lifespan than plasma cells. They produce antibodies. The first time an antigen is encountered, memory cells become plasma cells.

they have longer lifespan than plasma cells

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

they respond differently to invaders

Which secretion is not a barrier that prevents pathogens from entering the body? Mucus. Antigens. 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 _____. B cells ... macrophages macrophages ... B cells and T cells helper T cells ... plasma cells B cells ... plasma cells and memory cells T cells ... B cells

b cells... plasma cells and memory cells

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

body cells that have been infected

Which structure is not a component of the adaptive immune system? Hints Tissues. Thymus. Lymphatic ducts. Spleen.

tissues

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

catalizing the formation of DNA from an RNA template

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

cell mediated immune repsonses

Innate immunity and acquired immunity are both _____. Hints dependent on surface secretions from sebaceous and sweat glands, which give the skin an acidic pH that is unfavorable for bacterial colonization dependent exclusively on cell-mediated responses characteristics of all vertebrate animals 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 vertebrates

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. Bacterial cells Cytotoxic T cells B cells Helper T cells Epithelial cells

helper T cells

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

host cell membrane

Macrophages are _____. Hints the best defense against parasites short-lived cells that self-destruct soon after engulfing foreign invaders 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

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

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

True or false? B cells were originally isolated from the bursa in chickens, and their function is to produce antibodies; T cells were originally isolated from the thymus in mice, and their functions include killing host cells that are being infected with a virus. True False

true

Which of these cells is a phagocytic leukocyte that can engulf a foreign bacterium? macrophage B cell helper T cell cytotoxic T cell plasma cell

macrophage

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

macrophages

Engulfing-phagocytic cells of innate immunity of vertebrates include _____. I) neutrophils II) macrophages III) dendritic cells IV) natural killer cells I and III I and IV II and IV I, II, and III

1 2 3

Which of these cells is responsible for the rapidity of the secondary immune response? cytokines plasma cells macrophages memory cells cytotoxic T cells

memory cells

A primary reason for needing a new vaccine for influenza each year is that _____. Hints influenza is a disease that causes the apoptosis of all memory cells immunity typically disappears one month after recovery from a disease mutation in the influenza virus is frequent the first infection with influenza weakens the immune system 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

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

perforin... cell-mediated

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

plasma cells

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

plasma cells

Which of the following statements about the clonal-selection theory of immune system function is false? Antigens are recognized by receptor proteins inside the lymphocyte. Cloned cells persist after the pathogen is eliminated. Each lymphocyte recognizes one antigen. An activated lymphocyte makes many copies of itself in response to an infection.

Antigens are recognized by receptor proteins inside the lymphocyte.

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? B and T cells with receptors specific for the body's own molecules are destroyed by apoptosis. Only a very few lymphocytes produce receptors that attack the body's own molecules, so it's not a problem. 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.