BIOL 102 Chapter 43

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

A

Which of the following statements is true? An antibody has one antigen-binding site. A lymphocyte has receptors for a single antigen. Every antigen has a single epitope. A liver or muscle cell makes two classes of MHC molecule.

A lymphocyte has receptors for a single antigen.

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.

Which of the following statements about the clonal-selection theory of immune system function is false? Cloned cells persist after the pathogen is eliminated. Antigens are recognized by receptor proteins inside the lymphocyte. 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.

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

Antigens.

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

C

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.

A C. diff outbreak occurs in a nursing home. Which of the following would likely be best to stop the outbreak? Require hand-washing with an antibacterial soap when entering and leaving a room. Disinfect all areas for spores. Wash all the bedding in bleach. Prescribe antibiotics for all patients and employees.

Disinfect all areas for spores.

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

E

What is the role of recombinase in generating lymphocyte diversity? Early in B cell development, recombinase links one light-chain V gene segment to one J gene segment. Recombinase splices RNA to produce variable transcripts. 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.

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

Helper T cells

Vertebrate immune cells, which are phagocytic, include which of the following? I) neutrophils II) macrophages III) dendritic cells IV) natural killer cells I and III only II and IV only I and IV only I, II, and III

I, II, and III

Which of the following statements describe a component of 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 and III only II and IV I, II, and IV II, III, and IV

I, II, and IV

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. Neutrophils secrete substances that degrade bacterial cell walls. Platelets release proteins that form clots and decrease bleeding.

Platelets release proteins that form clots and decrease bleeding.

You are prescribed antibiotics for strep throat. Which of the following is true? The drug will only kill strep bacteria. The drug will allow only the good bacteria and viruses to survive. The drug will kill many kinds of viruses. The drug will kill many kinds of bacteria

The drug will kill many kinds of bacteria

Which of the following statements about epitopes is incorrect? B cell receptors bind to epitopes. T cell receptors bind to epitopes. There can be 10 or more different epitopes on each antigen. There is a one-to-one correspondence between antigen and epitope.

There is a one-to-one correspondence between antigen and epitope.

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

They have a longer lifespan than plasma cells.

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 chemicals that constrict blood vessels at some distance from the wound site. They secrete substances that degrade bacterial cell walls and engulf and digest the invaders. They release cytokines to stimulate the release of additional neutrophils and macrophages

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

True or False? The words "antigen" and "virus" are interchangeable.

True

You and your friend were equally exposed to a virus, but over the next few days, only your friend acquired flu-like symptoms and was ill for almost a week before recovering. Which one of the following is a logical explanation for this? Your friend had an autoimmune disorder. Your friend had allergies. You had an immunological memory of that virus. Your inflammatory response worked more quickly than your friend's response.

You had an immunological memory of that virus.

You are a doctor. A patient presents with diarrhea and tests positive for C. diff. Which of the following is true? Your patient may or may not have recently taken antibiotics. Your patient must have recently been on at least two different kinds of antibiotics. Your patient has not taken antibiotics in at least three years. Your patient must have recently been on antibiotics.

Your patient may or may not have recently taken antibiotics.

Which statement correctly describes the complement system? a set of proteins involved in innate but not acquired immunity a group of proteins that act together in a cascade fashion a set of proteins that act individually to attack and lyse microbes a group of proteins that includes interferons and interleukins

a group of proteins that act together in a cascade fashion

Which response is triggered when bacteria enter the body through a small cut in the skin? inactivation of erythrocytes apoptosis of nearby body cells release of interferons activation of a group of proteins called complement

activation of a group of proteins called complement

Which of these is absent from insect immunity? phagocytosis by hemocytes antibacterial digestive enzymes production of antimicrobial peptides activation of natural killer cells

activation of natural killer cells

Use the graphs to answer the following question. Mutant fruit flies that do not make antimicrobial peptides were tested for survival after infection with Neurospora crassa fungi or with Micrococcus luteus bacteria. The mutant flies were also transfected with the genes for antimicrobial peptides (drosomycin or defensin) and tested for survival. Which of the following hypotheses is best supported using the data? the presence of any single antimicrobial peptide protects against both fungal and bacterial pathogens wild-type flies with the full set of genes for antimicrobial peptides are highly susceptible to both fungal and bacterial pathogens adding the drosomycin gene to such mutants protects them from death by bacterial infection adding the defensin gene to such mutants protects them from death by bacterial infection

adding the defensin gene to such mutants protects them from death by bacterial infection

Which statement best describes the concept of clonal selection? macrophages can recognize specific T cells and B cells HIV (human immunodeficiency virus) can disrupt the immune system V, J, and C gene segments are rearranged an antigen can provoke production of high amounts of specific antibodies

an antigen can provoke production of high amounts of specific antibodies

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

antibodies

An organism that lacks their thymus would ________. have a reduced number of B cells and be unable to form antibodies be unable to differentiate and mature T cells 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 __________. circulating antibodies body cells that have been infected circulating proteins complement proteins extracellular viruses and bacteria

body cells that have been infected

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

catalyzing the formation of DNA from a RNA template

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

cell-mediated immune responses

Which of the following can trigger septic shock? increased production of neutrophils specific forms of viruses the presence of natural killer cells certain bacterial infections

certain bacterial infections

Innate immunity and adaptive immunity are both __________. 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 dependent on surface secretions from sebaceous and sweat glands, which give the skin an acidic pH that is unfavorable for bacterial colonization based on the trapping of microbes by mucus

characteristics of all vertebrate animals

T cells of the immune system include ________. cytotoxic and helper cells CD4, CD8, and plasma cells plasma, antigen-presenting, and memory cells lymphocytes, macrophages, and dendritic cells

cytotoxic and helper cells

The number of major histocompatibility (MHC) protein combinations possible in a given population is enormous. However, an individual in the population has a far more limited array of MHC molecules because ________. the MHC proteins are made from several different gene regions that are capable of rearranging in a number of ways each of the MHC genes has a large number of alleles, but each individual only inherits two for each gene once a B cell has matured in the bone marrow, it is limited to two MHC response categories MHC proteins from one individual can only be of class I or class II

each of the MHC genes has a large number of alleles, but each individual only inherits two for each gene

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

false

B cells are stimulated to differentiate under which of the following conditions? B cells produce IgE antibodies cytotoxic T cells present the class II MHC molecule-antigen complex on their surface helper T cells release cytokines B cells release cytokines

helper T cells release cytokines

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

host cell membrane

Which treatment could relieve the symptoms of an individual who has been bitten by a poisonous snake that has a fast-acting toxin? injection of antibodies to the toxin injection of interferon vaccination with a weakened form of the toxin injection of interleukin-1

injection of antibodies to the toxin

Acidity in human sweat is part of which type of immune system? innate immunity cell-mediated immune responses adaptive immunity acquired immunity

innate immunity

A nonfunctional CD4 protein on a helper T cell would result in the helper T cell being unable to ________. respond to circulating viral antigens stimulate a cytotoxic T cell interact with a class II MHC-antigen complex lyse tumor cells

interact with a class II MHC-antigen complex

Vaccination increases the number of _______ MHC molecules that can present an antigen. epitopes that the immune system can recognize. different receptors that recognize 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? B cell helper T cell macrophage plasma cell cytotoxic T cell

macrophage

Which of the following cells and signaling molecules are involved in the initial stages of the inflammatory response? lymphocytes and interferons phagocytes and cytokines mast cells and histamines dendritic cells and interferons

mast cells and histamines

Which of these is a characteristic of adaptive immunity but not innate immunity? interferons memory lysozyme inflammation

memory

A certain cell type has existed in the blood and tissue of its vertebrate host's immune system for over 20 years. One day, it recognizes a newly arrived antigen and binds to it, subsequently initiating a secondary immune response in the body. Which of the following cell types most accurately describes this cell? plasma cell thyroid cell memory cell macrophage

memory cell

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

memory cells

Which statement correctly describes both CD4 and CD8 proteins? receptors present on the surface of natural killer cells molecules present on the surface of T cells that interact with major histocompatibility (MHC) molecules molecules on the surface of antigen-presenting cells where they enhance B cell activity secreted by antigen-presenting cells

molecules present on the surface of T cells that interact with major histocompatibility (MHC) molecules

The primary reason for needing a new vaccine for influenza each year is that __________. the first infection with influenza weakens the immune system influenza is a disease that causes the apoptosis of all memory cells 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 mutation in the influenza virus is frequent

mutation in the influenza virus is frequent

Which of the following components make up a light chain of an immunoglobulin (Ig) molecule, of any class, with regions symbolized as C or V, H or L? two C regions and two V regions one C region and one V region one H region and one L region three H regions and one L region

one C region and one V region

Which of the following enhances phagocytosis of microbes by macrophages? I) the binding of antibodies to the surface of microbes II) antibody-mediated opsonization of microbes III) the release of cytokines by activated B cells only I and II only II and III only I and III I, II, and, III

only I and II

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

Which of the following can result in naturally acquired passive immunity? placental transfer of antibodies absorption of pathogens through mucous membranes ingestion of interferon injection of vaccine

placental transfer of antibodies

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

plasma 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 long-lived erythrocytes that can later secrete antibodies for the antigen vast numbers of B cells with random antigen-recognition receptors large quantities of the antigen initially recognized

short-lived plasma cells that secrete antibodies for the antigen

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

single-stranded RNA

Which statement best describes what causes the clumping of antigens when antibodies bind antigens? bonds form between class I and class II MHC molecules the antibodies denature the antibody has two identical binding sites disulfide bridges form between the antigens

the antibody has two identical binding sites

Which of the following protects both the eyes and the respiratory tract against infections? the secretion of complement proteins the secretion of lysozyme onto their surfaces the release of slightly alkaline secretions interferons produced by immune cells

the secretion of lysozyme onto their surfaces

Mucus occurs in both the respiratory and digestive tracts. Which answer best describes the main immunological function of mucus? to physically trap pathogens to sweep away debris to increase oxygen absorption to destroy pathogens (because mucus is acidic)

to physically trap pathogens

Vaccination offers protection against future exposure to pathogens because it ________. stimulates the complement system enhances the activity of macrophages triggers clonal expansion of lymphocytes promotes inflammation

triggers clonal expansion of lymphocytes

Which option best describes how a viral antigen, like EBV, is recognized by T cells? T cells recognize antibodies that have bound to viral particles. An antigen fragment is presented within class I MHC to the T cell receptor. The virus is engulfed by T cells using Toll-like receptors. Interferon proteins stick to the surface of infected cells.

An antigen fragment is presented within class I MHC to the T cell receptor.

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.

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. 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.

B and T cells with receptors specific for the body's own molecules are destroyed by apoptosis.

Clonal selection is the division of _____ that have been stimulated by binding to an antigen, which results in the production of cloned _____. macrophages ... B cells and T cells B cells ... macrophages T cells ... B cells B cells ... plasma cells and memory cells helper T cells ... plasma cells

B cells ... plasma cells and memory cells

Which statement best describes the difference between responses of effector B cells (plasma cells) and those of cytotoxic T cells? B cells secrete antibodies against a pathogen; cytotoxic T cells kill pathogen-infected host cells. B cells confer active immunity; cytotoxic T cells confer passive immunity. B cells carry out the cell-mediated response; cytotoxic T cells carry out the humoral response. B cells respond the first time a pathogen is present; cytotoxic T cells respond subsequent times.

B cells secrete antibodies against a pathogen; cytotoxic T cells kill pathogen-infected host 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? Genes for individual antigen-binding sites have a very high rate of mutation, generating great diversity. A large percentage of the vertebrate genome is devoted to genes for individual antigen-binding sites. By combining variable elements, the immune system assembles many different receptors from a much smaller collection of parts.

By combining variable elements, the immune system assembles many different receptors from a much smaller collection of parts.

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

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

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 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 more than several months ago, antibody production has ceased, and antibodies are no longer detectable.

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? The B cell recognizes the receptor-antigen complex and divides to produce plasma and memory cells. Helper T cells secrete antibodies against the viral antigen. Helper T cells recognize the receptor-antigen complex and cause plasma and memory cells to be produced to then produce antibodies. 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.

Which of the following are similarities between B cells and T cells? I) Both recognize antigens using immunoglobulin receptors. II) Both undergo clonal selection after encountering an antigen. III) Both maintain an immunological memory of previously encountered antigens. II and III I and II only III only II

II and III

Which statement is true about innate immunity? The extent of an innate immunity response depends on an infected animal's previous exposure to a pathogen Innate immunity is based on recognition of antigens that are specific to a pathogen Innate immunity is the first, and most general, mechanism of protection against pathogens. Only vertebrates use innate immunity

Innate immunity is the first, and most general, mechanism of protection against pathogens.

Which answer describes an advantage of having a system of adaptive immunity? It allows for the production of only a single type of antibody. 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 enables a rapid defense against an antigen that has been previously encountered.

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

While working as a microbiologist, you discover a new species of Clostridium. Which of the following is true? It is most likely disease causing. It is most likely harmless. It is harmless. It is disease causing.

It is most likely harmless.

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

Leukocytes recognize unique molecules on pathogens.

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

MHC (major histocompatibility complex) proteins

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

MHC protein.

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

Macrophages.

Use the following information to answer the following question. An otherwise healthy student in your class was infected with Epstein Barr virus (EBV) (the virus that causes infectious mononucleosis) when she was a child, at which time she had merely experienced a mild sore throat and swollen lymph nodes in her neck. When she is exposed to EBV again later in life, she does not get sick or develop any symptoms of mononucleosis. Which of the following statements explains why your classmate does not exhibit symptoms of EBV infection? Memory T cells recognized the virus upon the second exposure and activated cells that destroyed the virally infected cells. Complement proteins effectively controlled the EBV during the second infection. She was infected with a weaker strain of EBV during her second exposure. Her innate immune response was better at recognizing the EBV antigen during the second infection.

Memory T cells recognized the virus upon the second exposure and activated cells that destroyed the virally infected cells.

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

Tissues.

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

True or false? 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

Which of the following are typical features of an inflammatory response? release of substances to decrease the blood supply to an inflamed area 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

increased activity of phagocytes in an inflamed area

A boy falls while riding his bike. A scrape on his hand almost immediately begins to bleed and becomes red, warm, and swollen. Which type of response is most consistent with these symptoms? lytic response inflammatory response adaptive immune response autoimmune response

inflammatory response

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

is a molecule that evokes an immune response by a lymphocyte

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

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

Breast feeding confers which type of immunity to an infant? passive immunity cell-mediated immunity innate immunity active immunity

passive immunity

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

perforin ... cell-mediated

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

plasma cells

Which of the following is least likely to help a virus avoid triggering an adaptive immune response? having frequent mutations in genes for surface proteins infecting and killing helper T cells producing proteins very similar to those of other viruses infecting cells that produce very few MHC molecules

producing proteins very similar to those of other viruses

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

provirus

Within a differentiated B cell, the activity of which molecule results in the rearrangement of DNA sequences between variable regions and joining regions? RNA polymerase telomerase reverse transcriptase recombinase

recombinase

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

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

Which statement best describes an account of immunological memory? the ability of a helper T cell to signal B cells via cytokines the 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 nonself

the observation that someone who had recovered from the plague could safely care for those newly diseased

Which of the following should be the same in identical twins? the set of MHC molecules produced the set of antibodies produced the set of T cell antigen receptors produced the set of immune cells eliminated as self-reactive

the set of MHC molecules produced

Which of the following best explains why a bone marrow transplant may not be appropriate from a given donor to a given recipient even though they are compatible for blood transfusions? their blood-types may match but major histocompatibility (MHC) proteins may not be a match a blood type match is less stringent than a match required for transplant because blood is more tolerant of change there is only one allele for blood-type, but there are many alleles for bone-marrow type the given donor's MHC class II genes are not expressed in bone marrow

their blood-types may match but major histocompatibility (MHC) proteins may not be a match

Which option best describes why Jenner's use of cowpox virus as a vaccine against the smallpox virus was successful? the immune system responds nonspecifically to antigens 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

there are some epitopes (antigenic determinants) common to both pox viruses

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

they respond differently to invaders

Which of the following are molecules on mammalian cells that recognize macromolecules that are present in or on certain groups of pathogens? cytokines interferons toll-like receptors complement proteins

toll-like receptors

An epitope associates with which part of an antigen receptor or antibody? the light-chain constant regions only the tail variable regions of a heavy chain and light chain combined the heavy-chain constant regions only

variable regions of a heavy chain and light chain combined

A strain of fruit fly lacks the ability to produce Dicer-2 protein will most likely be susceptible to which of the following types of infections? viral protozoan fungal bacterial

viral