Chapter 12-Microbiology

Which event happens first during cytotoxic T-cell activation? Production of IL-2 and gamma-interferon receptors Secretion of granzymes and perforin CD8 binds to MHC molecules of infected cells Clonal proliferation

CD8 binds to MHC molecules of infected cells

What is the fate of activated cytotoxic T-cells? They can mature and attack infected cells. Each activated cytotoxic T-cell proliferates, forming a clone of cells specific to the same antigen. They are infected by viruses. They are destroyed via apoptosis. They can differentiate into long-lived memory T-cells. They proliferate into a clone of cells specific to the same antigen; some of these cells then differentiate into long-lived memory T-cells, while others mature to attack infected cells.

****They proliferate into a clone of cells specific to the same antigen; some of these cells then differentiate into long-lived memory T-cells, while others mature to attack infected cells.

Which of the following scenarios would result in long-term immunity? To be marked correct, you'll need to select all applicable statements, as there may be more than one correct answer. An otherwise healthy individual developing antibodies against Epstein-Barr virus following a case of mononucleosis Administration of an anti-tetanospasmin antitoxin after stepping on a rusted nail A newborn receiving protective IgA anti-pertussis antibodies through her mother's breastmilk A healthy individual receiving an MMR vaccination

***An otherwise healthy individual developing antibodies against Epstein-Barr virus following a case of mononucleosis Administration of an anti-tetanospasmin antitoxin after stepping on a rusted nail A newborn receiving protective IgA anti-pertussis antibodies through her mother's breastmilk ****A healthy individual receiving an MMR vaccination

When does MHC-II loading occur? During the fusion of vesicles containing MHC-II proteins with vesicles containing digested pathogens During phagocytosis of an invading pathogen During viral infection After passing through the endoplasmic reticulum

***During the fusion of vesicles containing MHC-II proteins with vesicles containing digested pathogens

Which of the following statements describes the purpose of gene shuffling? Gene shuffling allows an individual to switch from producing IgM antibody to IgG antibody. Gene shuffling allows for propagation of a specific lymphocyte whose receptor corresponds to the invading antigen. Gene shuffling eliminates lymphocyte clones that respond to autoantigens. Gene shuffling generates an enormous repertoire of antigen receptors during lymphocyte development.

***Gene shuffling generates an enormous repertoire of antigen receptors during lymphocyte development.

Based on the animation, T cells recognized the antigen displayed by what protein of the B cell? CD4 TCR BCR Antigen MHC

***MHC

Which of the cells listed below can present antigens on Class II MHC proteins? Virus infected epithelial cells Healthy epithelial cells Tumor cells Macrophages

***Macrophages

What is produced by the process of clonal expansion? Plasma cells Plasma cells, T cells, and memory B cells Plasma cells and memory B cells Memory B cells

***Plasma cells and memory B cells

Which T cell class is incorrectly matched with its description? TC: attack other T cells during self-tolerance screening Treg: ensures that immune responses subside once a threat subsides TH1: stimulate TC cells TH: identified by the CD4 proteins on the cell surface TH2: stimulate B cells to make antibodies

***TC: attack other T cells during self-tolerance screening

Natural killer cells are activated by TH2 cells. TH1 cells. bacterial cells. antigen-presenting cells.

***TH1 cells.

Which statement provides the best explanation of the need for self-tolerance screening of lymphocytes? The process which generates the vast array of diverse antigen receptors is a random process that could produce receptors which will bind to the body's own tissues. The process which generates the vast array of diverse antigen receptors is a highly-controlled process, so the generation of receptors which can bind to the body's own tissues is a rare occurrence due to a genetic mutation. It is necessary to have some lymphocytes with receptors that are self-tolerant to respond to intracellular infections by viruses. Self-tolerance involves "self" lymphocytes which bind to and form a protective layer over all body tissues. Lymphocytes which would attack the body's own tissues are never generated.

***The process which generates the vast array of diverse antigen receptors is a random process that could produce receptors which will bind to the body's own tissues.

Which is not a step in the process of B cell activation by a T-dependent antigen? Which is not a step in the process of B cell activation by a T-dependent antigen? release of cytokines by the T helper cell provide the second activation signal for the B cell binding of the antigen to the B cell receptor processing and displaying the antigen with MHC II on the B cell binding of the antigen to a T helper cell receptor interaction between co-stimulatory proteins on the B and T cells

***binding of the antigen to a T helper cell receptor

All the following apply to B cells except ***play a critical role in both the cellular and humoral responses. coordinate the humoral response by making antibodies. reside in the lymphoid tissue. originate in the bone marrow. mature in the bone marrow.

***play a critical role in both the cellular and humoral responses.

The branches of adaptive immunity are the cellular response and the memory response. the antigen response and the memory response. the cellular response and the humoral response. the cellular response, the humoral response, and the memory response. the humoral response and the memory response.

***the cellular response and the humoral response.

Choose the false statement about immune responses. Adaptive immune responses are always the same, regardless of the threat encountered, while innate immune responses are not. Adaptive immunity has a memory component, while innate immunity does not. Adaptive immunity takes longer to respond than innate immunity. Adaptive immunity is specific to a particular antigen, while innate immunity is not.

**Adaptive immune responses are always the same, regardless of the threat encountered, while innate immune responses are not.

How is the immune system able to recognize a limitless number of different antigens and epitopes? Each lymphocyte is coated with many different receptors, each of which recognizes a different epitope. If a lymphocyte encounters an antigen it does not recognize, it immediately switches receptors until it finds one that is a match. A genetic "memory" of the pathogens your parents encountered (and their parents and so on) is passed on to each generation, increasing the number of possible responses over time. Each lymphocyte is coated with many different receptors, each of which recognizes a different epitope AND the immune system produces a wide variety of lymphocytes. While each lymphocyte carries receptors that recognize only one type of epitope, the immune system produces a wide variety of lymphocytes each of which carries unique receptors.

**While each lymphocyte carries receptors that recognize only one type of epitope, the immune system produces a wide variety of lymphocytes each of which carries unique receptors.

A substance that may trigger an immune response, if presented in the right context is termed a(n) effector. antigen. antibody. hapten. cytokine.

**antigen.

All the following apply to T cells except have the capacity to recognize virtually any type of antigen. originate in the bone marrow. mature in the thymus. coordinate the humoral response by making antibodies. reside in the lymphoid tissue.

**coordinate the humoral response by making antibodies.

Which branch of the immune system produces antibodies? Which branch of the immune system produces antibodies? Innate cellular response Adaptive cellular response Innate molecular response Adaptive humoral response

Adaptive humoral response

When do helper T-cells develop into TH1 or TH2 cells? Immediately after the binding of the CD4 receptor After proliferation into a clonal population Before autostimulation After B cell activation

After proliferation into a clonal population

What makes agglutination by antibodies possible? Antibodies can recognize bacteria as well as viruses. Antibodies can inactivate toxins. Each antibody has at least two antigen-binding sites. Antibodies are produced by plasma cells.

Each antibody has at least two antigen-binding sites.

How can a sufficient humoral immune response occur if a plasma cell only lives for a few days? T cells can also produce antibodies. Memory B cells can also produce antibodies. Each plasma cell can proliferate into more plasma cells. Each plasma cell can produce up to 2000 antibodies every second.

Each plasma cell can produce up to 2000 antibodies every second.

What is an antigen? A cell that remains in the lymphatic tissues to rapidly recognize pathogens in a subsequent exposure A cell that organizes the cellular and humoral branches of adaptive immunity Any molecule that, when presented in the right context, will stimulate an immune response A molecule made by plasma cells

Any molecule that, when presented in the right context, will stimulate an immune response

Which type of cell directly binds an antigen, rather than requiring an antigen-presenting cell to first process the antigen? B cells T helper cells T cytotoxic cells Dendritic cells

B cells

TH2 cells produce cytokines that activate natural killer cells. cytotoxic T-cells. B cells. macrophages.

B cells.

Which of the following statements regarding B lymphocytes is/are true? To be marked correct, you'll need to select all applicable statements, as there may be more than one correct answer. B lymphocytes are found in high concentration at various sites throughout the body, including the lymphatic system and the bloodstream. B lymphocytes are both produced and mature in the bone marrow. Once activated, B lymphocytes have the ability to produce antibodies. B lymphocytes carry out cell-mediated immunity.

B lymphocytes are both produced and mature in the bone marrow. Once activated, B lymphocytes have the ability to produce antibodies.

What is the function of the CD8 receptor? Activate cytokines Produce gamma interferon Produce IL-2 Bind to MHC molecules

Bind to MHC molecules

Antigen processing and presentation is only accomplished by bacterial cells. is the way foreign cells engulf macrophages. is a way for viruses to infect cells. is a way for a cell to give information about its activities.

is a way for a cell to give information about its activities.

The cellular branch of adaptive immunity is based on antibody production. is organized by T helper cells and carried out by T cytotoxic cells. is organized by T cytotoxic cells and carried out by T helper cells. does not involve a memory function. is based on the activity of both T and B cells.

is organized by T helper cells and carried out by T cytotoxic cells.

In contrast to a primary immune response, immunological memory generates higher antibody titers. provides a rapid reactivation of humoral responses only by generating higher antibody titers and antibodies with increased affinity for its antigen. provides a rapid reactivation of both cellular and humoral responses including generating higher antibody titers and antibodies with increased affinity for its antigen. generates antibodies with enhanced affinity for its antigen. provides a rapid reactivation of both cellular and humoral responses.

provides a rapid reactivation of both cellular and humoral responses including generating higher antibody titers and antibodies with increased affinity for its antigen.

What is the role of memory cells? provide immune protection specifically for central nervous system suppress the cellular response once the infection has passed remain in the lymphoid tissue to rapidly proliferate and differentiate upon subsequent exposure to the same pathogen prevent an immune response against members of the normal microbiota circulate in the body at elevated levels to maintain an active attack against any possible pathogen

remain in the lymphoid tissue to rapidly proliferate and differentiate upon subsequent exposure to the same pathogen

Which molecule triggers apoptosis? Granzyme IL-2 Gamma-interferon Perforin MHC

Granzyme

Place the stages of adaptive immunity in order from first to last. I. Antigen elimination and memory II. Lymphocyte activation III. Antigen presentation IV. Lymphocyte proliferation and differentiation III, IV, II, I II, III, IV, I IV, III, II, I III, II, IV, I

III, II, IV, I

What type of antigen typically binds to MHC I to present an MCH I-antigen complex? Extracellular antigen Phagocytized bacterial proteins Intracellular antigen Exogenous antigen

Intracellular antigen

What is the role of MHC I in the immune response? MHC I is found on all body cells except red blood cells. MHC I is found only on antigen-presenting cells and presents a sample of cellular proteins, including those of any intracellular pathogens, to T cells. MHC I is found only on antigen-presenting cells. MHC I is found on all body cells except red blood cells and presents a sample of cellular proteins, including those of any intracellular pathogens, to T cells. MHC I presents a sample of cellular proteins, including those of any intracellular pathogens, to T cells.

MHC I is found on all body cells except red blood cells and presents a sample of cellular proteins, including those of any intracellular pathogens, to T cells.

Which statement is not true about MHC II? When bound to antigen, MHC II serves a key role in activation of the appropriate T cells. MHC II interacts with the CD4 receptor on T helper cells. MHC II interacts with both the CD4 and CD8 receptors on T helper and T cytotoxic cells. MHC II primarily displays extracellular antigens which have been phagocytized. MHC II is present only on antigen-presenting cells.

MHC II interacts with both the CD4 and CD8 receptors on T helper and T cytotoxic cells.

Which proteins on the antigen-presenting cell are recognized by the helper T-cell? CD8 receptors MHC proteins IL-1 receptors IL-2 receptors

MHC proteins

Why would a body cell that is not a phagocyte need to present antigens? All cells of the body can engulf invading cells. Antigens are required for cell-to-cell attachment. Antigens are infectious and can spread to normal cells. Non-phagocytic body cells can become infected with a virus.

Non-phagocytic body cells can become infected with a virus.

Where are MHC molecules located on a cell? Inside the cell cytoplasm They are not associated with any one location on the cell On the surface of the cell In the nucleus

On the surface of the cell

Antibodies are secreted from which type of cell? Dendritic cells Plasma cells T helper cells T cytotoxic cells

Plasma cells

What is the role of plasma cells in humoral immunity? Plasma cells produce antibodies. Plasma cells activate the complement system. Plasma cells neutralize toxins. Plasma cells are phagocytes. Plasma cells engulf viruses.

Plasma cells produce antibodies.

Which of the following statements is/are true regarding T cytotoxic cell antigen elimination? To be marked correct, you'll need to select all applicable statements, as there may be more than one correct answer. Released interferons by cancer cells or infected cells increases production of MHC II, increasing the likelihood that cytotoxic T cells will "seek and destroy" these cells. ***Interferons released by infected or cancer cells attract and activate cytotoxic T cells, while cytokines released by the cytotoxic T cells attract natural killer cells and macrophages. ****Following apoptosis by cytotoxic T cells, macrophages and natural killer cells clear the dead cells. ***Once the threat has been detected by the T cell receptor, the cytotoxic T cell releases perforins that form pores in the target cell and granzymes, which enter through pores to trigger apoptosis.

Released interferons by cancer cells or infected cells increases production of MHC II, increasing the likelihood that cytotoxic T cells will "seek and destroy" these cells. ***Interferons released by infected or cancer cells attract and activate cytotoxic T cells, while cytokines released by the cytotoxic T cells attract natural killer cells and macrophages. ****Following apoptosis by cytotoxic T cells, macrophages and natural killer cells clear the dead cells. ***Once the threat has been detected by the T cell receptor, the cytotoxic T cell releases perforins that form pores in the target cell and granzymes, which enter through pores to trigger apoptosis.

Choose the false statement. B cells usually require T cells for full activation. Antibodies activate classical complement cascades. T cytotoxic cells directly combat antigens. T helper cells directly combat antigens.

T helper cells directly combat antigens.

An antigen that is potent enough to activate a B cell on its own is known as BCR. T-independent antigens. antibodies. T-dependent antigens.

T-independent antigens.

Which receptor on the helper T-cell recognizes the specific antigen from an antigen-presenting cell? TCR IL-1 Receptors IL-2 Receptors CD4

TCR

Which of the following most accurately describes how a pathogenic bacterium might be affected by antibodies? The antibodies may stick to multiple bacteria, causing agglutination. The antibodies may coat the surface of the bacteria (opsonization), allowing for it to be tagged for phagocytosis. The antibodies may block proteins necessary for binding the pathogen to the host. The antibodies may block proteins necessary for binding the pathogen to the host, may opsonize the bacterium, or may agglutinate bacteria.

The antibodies may block proteins necessary for binding the pathogen to the host, may opsonize the bacterium, or may agglutinate bacteria.

Which organelle assists directly with the presentation of MHC-I antigens? The phagosome The nucleus The mitochondria The endoplasmic reticulum The Golgi apparatus

The endoplasmic reticulum

What is apoptosis? A protein molecule that forms a pore in the membranes of infected cells. The process of programmed cell death. The proliferation of cytotoxic T-cells. The receptor on a cytotoxic T-cell that recognizes MHC molecules.

The process of programmed cell death.

Which of the following best characterizes clonal selection? The production of identical B cells producing the same antibody The production of identical T cells producing the same antibody The production of identical B cells producing different antibodies The production of different antigens by the same B cell

The production of identical B cells producing the same antibody

Which of the following statements concerning the secondary response is true? The secondary immune response is slower than the primary immune response. In order to stimulate an immune reaction, the secondary immune response requires a higher concentration of antigen than the primary immune response. The secondary response results in production of antibodies with a higher affinity for the antigen. The secondary immune response is stronger than the primary immune response due to the increased production of IgM antibody from plasma cells.

The secondary response results in production of antibodies with a higher affinity for the antigen.

What is a feature of the small fragments presented by MHC-I proteins? They are derived from bacteria. They are large proteins from the host. They are small fragments of nucleic acids, 8-10 nucleotides in length. They are small peptides, roughly 8-10 amino acids long.

They are small peptides, roughly 8-10 amino acids long.

How do phagocytes communicate to other cells what they have captured? They spread viruses to other cells. They present antigens from engulfed foreign cells. They engulf virally infected cells.

They present antigens from engulfed foreign cells.

The amount of antibody present in the blood is termed the antibody ________. affinity specificity titer effector isotype

titer

Which of the following statements accurately differentiates the adaptive immune system and the innate immune system? To be marked correct, you'll need to select all applicable statements, as there may be more than one correct answer. Unlike the innate immune system, the adaptive immune system has the ability to distinguish self from foreign antigens. Unlike the innate immune system, the adaptive immune system is characterized by memory and specificity. Unlike the innate immune system, the adaptive immune system is able to respond immediately to a pathogen. Unlike the innate immune system, the adaptive immune system includes both a cellular and humoral response.

Unlike the innate immune system, the adaptive immune system has the ability to distinguish self from foreign antigens. ***Unlike the innate immune system, the adaptive immune system is characterized by memory and specificity. Unlike the innate immune system, the adaptive immune system is able to respond immediately to a pathogen. ****Unlike the innate immune system, the adaptive immune system includes both a cellular and humoral response.

What is the role of B cell receptors (BCRs) and T cell receptors (TCRs) in the immune response? to recognize specific epitopes of an antigen to combine with haptens so they can stimulate an immune response to communicate with lymphocytes and other white blood cells to release chemicals which destroy pathogens to release the cytokines needs for immune cell stimulation

to recognize specific epitopes of an antigen

Antibodies do all the following except activate killing by T cytotoxic cells. increase phagocytosis by agglutination of antigens. activate the complement cascade. neutralize antigens to prevent binding to host cells. increase phagocytosis by opsonization.

activate killing by T cytotoxic cells.

The difference between T cell activation by normal antigens and T cell activation by superantigens is that superantigens are not processed and presented by APCs. suppress cytokine release. cause nonspecific activation of many T cells at once, including those that would not normally recognize the antigen. are not processed and presented by APCs and cause nonspecific activation of many T cells at once, including those that would not normally recognize the antigen. cause nonspecific activation of many T cells at once, including those that would not normally recognize the antigen and suppress cytokine release.

are not processed and presented by APCs and cause nonspecific activation of many T cells at once, including those that would not normally recognize the antigen.

T-independent antigens may be polysaccharides or proteins, and are not able to bind multiple B cell receptors on a given B cell. are usually polysaccharides. are usually proteins. are usually polysaccharides and able to bind multiple B cell receptors on a given B cell. are able to bind multiple B cell receptors on a given B cell.

are usually polysaccharides and able to bind multiple B cell receptors on a given B cell.

T helper cells release _____ to activate B cells. antibodies cytokines MHC I MHC II

cytokines