Immuno Midterm Practice Questions PDF

LECTURE 1 innate 1. What role does the innate immune system play? antigen non-specific o A. It provides long-term immunity by remembering past infection...

LECTURE 1 innate 1. What role does the innate immune system play? antigen non-specific o A. It provides long-term immunity by remembering past infections. B. It acts as a first line of defense, responding to pathogens immediately. FAST C. It produces antibodies specific to each pathogen. D. It targets specific pathogens after being exposed to them. - Answer: B. It acts as a first line of defense, responding to pathogens immediately. 2. What role does the adaptive immune system play? - A. It provides a non-specific response to all pathogens. B. It involves cells that constantly patrol the body for infections. C. It provides long-term immunity by creating pathogen-specific responses. ⑧ D. It acts as the first barrier against pathogens. Answer: C. It provides long-term immunity by creating pathogen-specific responses. 3. What are the characteristics of the innate immune system? G A. Specific, adaptive, and memory-based response. B. Rapid, non-specific, and lacks memory. C. Delayed, specific, and involves antibodies. D. Only activates after exposure to a pathogen. Answer: B. Rapid, non-specific, and lacks memory. 4. What are the characteristics of the adaptive immune system? E A. Provides rapid response without prior exposure to pathogens. B. Involves specialized memory cells and is pathogen-specific. C. Non-specific defense with immediate action. D. Responds similarly to all pathogens regardless of prior infection. Answer: B. Involves specialized memory cells and is pathogen-specific. 5. What are some general functions of B-cells? - A. Directly destroy infected cells. B. Produce antibodies and help neutralize pathogens. - C. Engulf pathogens through phagocytosis. D. Activate complement proteins for non-specific defense. - Answer: B. Produce antibodies and help neutralize pathogens. cellular 6. What are some general functions of T-cells? A. Engulf pathogens directly. 9B. Recognize and kill infected host cells or help activate other immune cells. C. Produce antibodies for pathogen neutralization. D. Create memory responses against bacterial infections only. Answer: B. Recognize and kill infected host cells or help activate other immune cells. 7. How do humoral and cell-mediated immunity cells work together? , A. Both are responsible for directly attacking pathogens using the same method. B. Humoral immunity involves T-cells attacking pathogens, while cell-mediated immunity is about antibody production. O C. B-cells produce antibodies (humoral immunity) while T-cells attack infected cells (cell-mediated immunity). I D. Both work separately without interaction. Answer: C. B-cells produce antibodies (humoral immunity) while T-cells attack infected cells (cell-mediated immunity). 8. How does the process of clonal selection work? A. It involves the random production of antibodies for all pathogens. O B. Specific B and T cells proliferate after recognizing their matching antigen. C. Every B and T cell responds to all antigens equally. D. It refers to immune cells attacking themselves to prevent overpopulation. Answer: B. Specific B and T cells proliferate after recognizing their matching antigen. 9. How does clonal selection affect B and T-cell antigen receptor diversity? "o A. It reduces diversity by producing a single type of receptor for all cells. B. It randomly produces receptors that can bind to any antigen. C. It ensures diversity by producing many different receptors specific to various antigens. D. It eliminates diversity, creating identical immune cells.  Answer: C. It ensures diversity by producing many different receptors specific to various antigens. 10. Why is the clonal selection theory important? o A. It helps explain how immune cells are able to respond to any pathogen encountered. B. It explains why the immune system attacks the body's own cells. C. It shows why B-cells and T-cells are unable to recognize pathogens. D. It proves the immune system does not adapt over time. Answer: A. It helps explain how immune cells are able to respond to any pathogen encountered. * LYMPHOCYTES : recognize antigens thru receptors LECTURE 2 their surface that bind to them on specifically * 1. How do lymphocytes recognize antigens? A. Lymphocytes recognize antigens through antibodies that bind to pathogens. B. Lymphocytes recognize antigens through receptors on their surface that specifically bind to them. O C. Lymphocytes recognize antigens through phagocytosis, engulfing any cell they encounter. D. Lymphocytes recognize antigens through cytokine release, signaling the presence of pathogens. Answer: B. Lymphocytes recognize antigens through receptors on their surface that specifically bind to them. & * APCs engulf pathogens a display antigen fragments - on 2. What are antigen-presenting cells? their surface lymphocytes for A. Cells that attack pathogens directly by releasing antibodies into the bloodstream. B. Cells that engulf pathogens and display antigen fragments on their surface for lymphocytes. O C. Cells that release cytokines to signal the presence of a pathogen to nearby cells. D. Cells that recognize antigens and destroy infected host cells using perforins. Answer: B. Cells that engulf pathogens and display antigen fragments on their surface for lymphocytes. APCs 7 T cell 3. How do antigen-presenting cells convey information to lymphocytes? A. They secrete antibodies that coat the pathogen for lymphocytes to recognize. - O B. They present antigen fragments on their surface using MHC molecules for lymphocytes to detect. / C. They engulf pathogens and directly transfer the antigens into lymphocytes. D. They release cytokines that trigger lymphocyte proliferation and differentiation. Answer: B. They present antigen fragments on their surface using MHC molecules for lymphocytes to detect. 4. What is a B-cell receptor (BCR), and how does it work? i A. A receptor that binds specifically to antigens on pathogens and triggers an immune response. B. A receptor that engulfs pathogens after binding to any antigen found on their surface. C. A receptor that releases cytokines to signal other cells to attack the pathogen. D. A receptor that directly attacks infected cells by releasing antibodies into the bloodstream. Answer: A. A receptor that binds specifically to antigens on pathogens and triggers an immune response. 5. What is a T-cell receptor (TCR), and how does it work? A. A receptor that engulfs pathogens and directly digests their antigens. B. A receptor that binds to antigen fragments presented by antigen-presenting cells. C. A receptor that releases antibodies to neutralize pathogens in the bloodstream. D. A receptor that triggers apoptosis in infected cells upon binding to any antigen. Answer: B. A receptor that binds to antigen fragments presented by antigen-presenting cells. 6. What do BCRs and TCRs do after activation? E A. BCRs secrete antibodies while TCRs proliferate and destroy infected cells. B. BCRs attack infected cells while TCRs release cytokines to coordinate the immune response. C. BCRs stimulate phagocytosis while TCRs signal other immune cells to produce antibodies. - D. BCRs and TCRs migrate to lymph nodes to deactivate the immune response. Answer: A. BCRs secrete antibodies while TCRs proliferate and destroy infected cells. 7. What are the functions of antibodies in the immune system? , A. Antibodies directly destroy pathogens by phagocytosis and lysing their cell walls. B. Antibodies bind to antigens on pathogens, neutralizing them and facilitating their removal. C. Antibodies recognize and engulf pathogens to break them down inside lymph nodes. D. Antibodies trigger the release of cytokines to signal other immune cells to attack pathogens. Answer: B. Antibodies bind to antigens on pathogens, neutralizing them and facilitating their removal. 8. What is the general structure of an antibody? - A. An antibody has a single heavy chain and a light chain that forms a circle to bind pathogens. O B. An antibody consists of two heavy chains and two light chains, forming a Y-shaped molecule. C. An antibody has three light chains that form a straight line to bind multiple antigens. - D. An antibody consists of four light chains arranged in a square to trap pathogens. - Answer: B. An antibody consists of two heavy chains and two light chains, forming a Y-shaped molecule. ADE GM 9. What are the five major classes of antibodies? OA. IgA, IgG, IgM, IgD, IgE are the five major classes that serve different immune functions. / IgE, IgF are the five major classes that bind to different pathogen types. B. IgA, IgD, IgC, Y C. IgA, IgB, IgM, IgG, IgE are the five major classes responsible for cytokine release. D. IgA, IgH, IgM, IgK, IgE are the five major classes involved in direct pathogen destruction. Answer: A. IgA, IgG, IgM, IgD, IgE are the five major classes that serve different immune functions. LECTURE 3 1. What are the physical barriers of the innate immune system, and how do they prevent infection? 8 A. Physical barriers include skin and mucous membranes, which block pathogen entry and trap microbes. Y B. Physical barriers include enzymes and cytokines, which chemically destroy pathogens. C. Physical barriers include macrophages and dendritic cells, which engulf pathogens through phagocytosis. / D. Physical barriers include antibodies and B-cells, which neutralize pathogens in the bloodstream. Answer: A. Physical barriers include skin and mucous membranes, which block pathogen entry and trap microbes. 2. What are the chemical barriers of the innate immune system, and how do they prevent infection? A. Chemical barriers include macrophages and neutrophils, which engulf pathogens in tissues. O B. Chemical barriers include enzymes, acids, and antimicrobial peptides that inhibit microbial growth. C. Chemical barriers include natural killer cells, which detect and destroy infected cells. I D. Chemical barriers include skin and mucous membranes, which block pathogen entry.  Answer: B. Chemical barriers include enzymes, acids, and antimicrobial peptides that inhibit microbial growth. ↑ 3. What are the cellular/molecular components of the innate immune system, and how do they prevent infection? I A. Cellular components include skin and mucous membranes that provide a physical barrier against pathogens. B. Cellular components include natural killer cells, macrophages, and neutrophils that destroy pathogens through various methods. O C. Cellular components include antibodies and T-cells that specifically target and destroy pathogens after infection. S D. Cellular components include cytokines and phagocytes, which produce antibodies and neutralize pathogens. Answer: B. Cellular components include natural killer cells, macrophages, and neutrophils that destroy pathogens through various methods. 4. What are phagocytes, and how do they work? A. Phagocytes are cells that produce antibodies to target pathogens for destruction. - O B. Phagocytes are cells that engulf and digest pathogens, removing them from the body. C. Phagocytes are cells that release cytokines to signal the presence of a pathogen to other immune cells. / D. Phagocytes are cells that create memory responses to specific pathogens for long-term immunity. Answer: B. Phagocytes are cells that engulf and digest pathogens, removing them from the body. 5. What role do macrophages play in the innate immune system? A. Macrophages directly kill pathogens by producing antibodies that bind to them. O B. Macrophages engulf pathogens, present antigens to other immune cells, and secrete cytokines. C. Macrophages release histamine to cause inflammation and attract neutrophils to infection sites. / D. Macrophages create antibodies to neutralize pathogens before engulfing them. Answer: B. Macrophages engulf pathogens, present antigens to other immune cells, and secrete cytokines. * 6. What role do neutrophils play in the innate immune system? A. Neutrophils engulf pathogens, release enzymes to digest them, and form pus at infection sites. B. Neutrophils produce antibodies to neutralize pathogens before engulfing them. C. Neutrophils release cytokines that signal other immune cells to the site of infection. O D. Neutrophils create memory responses against pathogens and prevent reinfection. Answer: A. Neutrophils engulf pathogens, release enzymes to digest them, and form pus at infection sites. * 7. What role do dendritic cells play in the innate immune system? A. Dendritic cells produce antibodies that neutralize pathogens in the bloodstream. B. Dendritic cells engulf pathogens and present their antigens to T-cells to initiate an adaptive response. C. Dendritic cells release cytokines that attract other immune cells to the site of infection. jD. Dendritic cells directly kill infected cells through apoptosis and lysis. Answer: B. Dendritic cells engulf pathogens and present their antigens to T-cells to initiate an adaptive response. 8. What role do natural killer (NK) cells play in the innate immune system? o A. NK cells kill infected or cancerous cells by recognizing and inducing their death. B. NK cells produce antibodies that neutralize pathogens in the bloodstream. C. NK cells engulf pathogens through phagocytosis and present their antigens to T-cells. D. NK cells release cytokines to signal other immune cells to attack infected cells. Answer: A. NK cells kill infected or cancerous cells by recognizing and inducing their death. 9. How do NK cells recognize and kill infected or transformed cells? A. NK cells release antibodies to bind pathogens before engulfing and digesting them. E B. NK cells recognize abnormal proteins on the surface of infected cells and trigger cell death through perforins. C. NK cells present antigens to B-cells, which produce antibodies to neutralize the infection. - D. NK cells release enzymes that digest the cell wall of pathogens, leading to their destruction. Answer: B. NK cells recognize abnormal proteins on the surface of infected cells and trigger cell death through perforins.  LECTURE 4 1. What are PAMPs? What are PRRs? O A. PAMPs are pathogen-associated molecular patterns, and PRRs are pattern recognition receptors that detect PAMPs. B. PAMPs are proteins made by immune cells, while PRRs are antibodies that bind to pathogens. C. PAMPs are antigens produced by viruses, and PRRs are T-cell receptors that recognize them. D. PAMPs are pathogen-activated molecules, and PRRs are receptors found on antibodies. Answer: A. PAMPs are pathogen-associated molecular patterns, and PRRs are pattern recognition receptors that detect PAMPs. 2. How do PRRs recognize PAMPs? A. PRRs recognize PAMPs by binding to antibodies already attached to pathogens. g B. PRRs recognize PAMPs by directly binding to common molecular structures on pathogens. C. PRRs recognize PAMPs by engulfing pathogens and breaking down their proteins. T D. PRRs recognize PAMPs by secreting cytokines that signal other immune cells. Answer: B. PRRs recognize PAMPs by directly binding to common molecular structures on pathogens. * 3. On which cells do we find PRRs? A. PRRs are found on antibodies and B-cells that recognize specific pathogens. B. PRRs are found on all immune cells, including macrophages, dendritic cells, and neutrophils. GC. PRRs are found only on B-cells and T-cells that respond to antigen presentation. D. PRRs are found on antibodies that neutralize pathogens by binding to them. Answer: B. PRRs are found on all immune cells, including macrophages, dendritic cells, and neutrophils. 4. What role do interferons play in the immune system? 6 A. Interferons are proteins that directly attack pathogens by digesting their cell walls. B. Interferons are signaling molecules that help cells resist viral infections and activate other immune responses. C. Interferons are enzymes that break down pathogens and prepare them for destruction by antibodies. D. Interferons are antibodies that neutralize viruses and prevent them from infecting cells.  Answer: B. Interferons are signaling molecules that help cells resist viral infections and activate other immune responses. 5. What are the components of the complement system? A. The complement system is made up of antibodies and B-cells that neutralize pathogens. O B. The complement system includes proteins that assist in opsonization, inflammation, and pathogen lysis. / C. The complement system consists of natural killer cells and macrophages that engulf pathogens. / The complement system contains cytokines and chemokines that signal immune responses. D. Answer: B. The complement system includes proteins that assist in opsonization, inflammation, and pathogen lysis. 6. How is the complement system activated, and how does it affect an immune response? A. The complement system is activated by macrophages, which engulf pathogens and destroy them. O B. The complement system is activated by antibodies binding to pathogens, leading to opsonization, inflammation, and pathogen lysis. C. The complement system is activated by T-cells that secrete cytokines, which neutralize pathogens. D. The complement system is activated by interferons that directly destroy viral proteins. Answer: B. The complement system is activated by antibodies binding to pathogens, leading to opsonization, inflammation, and pathogen lysis. 7. What are the components of the complement system? O A. The complement system includes proteins like C3, C5, and others that help destroy pathogens. B. The complement system includes natural killer cells that destroy infected cells directly. C. The complement system consists of antibodies that bind to pathogens for destruction. D. The complement system contains cytokines that stimulate macrophages to engulf pathogens. Answer: A. The complement system includes proteins like C3, C5, and others that help destroy pathogens. 8. What is a membrane attack complex (MAC), and how can it assist in removing pathogens? * A. MAC is a structure formed by immune cells that engulf and digest pathogens. o  B. MAC is a protein complex that forms pores in pathogen membranes, leading to their destruction. C. MAC is a cytokine released by macrophages to activate other immune cells in pathogen removal. D. MAC is an antibody that binds to pathogens and prevents them from entering host cells. Answer: B. MAC is a protein complex that forms pores in pathogen membranes, leading to their destruction. 9. What are antimicrobial peptides (AMPs), and how do they work? A. AMPs are proteins that bind to antigens and neutralize them before they can infect cells. 8 B. AMPs are small molecules that destroy pathogen membranes and inhibit their growth. C. AMPs are enzymes that digest pathogens after they have been engulfed by phagocytes. D. AMPs are antibodies that neutralize bacterial toxins and prevent their spread. Answer: B. AMPs are small molecules that destroy pathogen membranes and inhibit their growth. 10. What is a respiratory burst, and how is it used by innate immune cells? A. A respiratory burst is when innate immune cells engulf pathogens and destroy them with enzymes. g B. A respiratory burst is the release of reactive oxygen species by phagocytes to kill pathogens. C. A respiratory burst is the process where immune cells produce cytokines to activate other - cells. D. A respiratory burst is the release of interferons that help cells resist viral infections. Answer: B. A respiratory burst is the release of reactive oxygen species by phagocytes to kill pathogens. LECTURE 5 1. What are the essential features or signs of inflammation? OA. Heat, redness, swelling, pain, and loss of function are signs of inflammation. B. Cold, stiffness, sweating, nausea, and fever are signs of inflammation. C. Coughing, sneezing, itching, tiredness, and fever are signs of inflammation. ID. Blisters, rash, dizziness, fatigue, and loss of strength are signs of inflammation. Answer: A. Heat, redness, swelling, pain, and loss of function are signs of inflammation.  2. What is an inflammatory cascade, and how does it occur? A. The inflammatory cascade is a series of immune reactions caused by pathogen toxins. O B. The inflammatory cascade is the sequential release of cytokines and immune responses to injury or infection. C. The inflammatory cascade is the continuous release of histamine in response to allergens. - D. The inflammatory cascade is the rapid spread of infection from one part of the body to another. Answer: B. The inflammatory cascade is the sequential release of cytokines and immune responses to injury or infection. 3. What is vasodilation, and why is it important in inflammation? J A. Vasodilation is the contraction of blood vessels to reduce blood flow during injury. B. Vasodilation is the widening of blood vessels, increasing blood flow to deliver immune cells and nutrients. TC. Vasodilation is the swelling of tissues due to excess fluid, trapping pathogens. D. Vasodilation is the decrease in blood pressure, allowing tissues to repair faster. Answer: B. Vasodilation is the widening of blood vessels, increasing blood flow to deliver immune cells and nutrients. 4. Which proinflammatory cytokines are released to trigger an inflammatory response? & A. Interleukin-10 (IL-10), Interferon-gamma (IFN-γ), and TGF-beta are proinflammatory cytokines. B. Tumor necrosis factor (TNF), Interleukin-1 (IL-1), and Interleukin-6 (IL-6) are proinflammatory cytokines. C. Interleukin-4 (IL-4), IL-10, and growth factors are proinflammatory cytokines. D. Interferon-alpha, IL-2, and IL-12 are proinflammatory cytokines released during infections. Answer: B. Tumor necrosis factor (TNF), Interleukin-1 (IL-1), and Interleukin-6 (IL-6) are proinflammatory cytokines. 5. What is the purpose of a fever, and where is it activated? A. Fever is caused by immune cells overheating, and it helps cool down the body during infection. O B. Fever is an immune response that increases body temperature to inhibit pathogen growth, activated by the hypothalamus. C. Fever is a result of rapid metabolism, and it causes inflammation in body tissues.  D. Fever is triggered by muscle contractions, which generate heat to prevent the spread of infection. Answer: B. Fever is an immune response that increases body temperature to inhibit pathogen growth, activated by the hypothalamus. 6. What are proinflammatory cytokines, and what role do they play in a fever? A. Proinflammatory cytokines cause muscle spasms that generate heat and increase body - temperature. O B. Proinflammatory cytokines signal the hypothalamus to raise the body's set temperature, inducing a fever. C. Proinflammatory cytokines trigger the skin to release heat and reduce infection rates. - D. Proinflammatory cytokines help regulate digestion and improve the body's ability to absorb nutrients during illness. Answer: B. Proinflammatory cytokines signal the hypothalamus to raise the body's set temperature, inducing a fever. 7. Which proinflammatory cytokines are responsible for activating a fever? * A. Interleukin-12 (IL-12), Interleukin-10 (IL-10), and Interferon-beta are responsible for fever activation. B. Tumor necrosis factor (TNF), Interleukin-1 (IL-1), and Interleukin-6 (IL-6) are responsible for fever activation. C. Interleukin-2 (IL-2), IL-8, and growth factors trigger a fever during infections. D. IL-4, Interleukin-18 (IL-18), and TGF-beta induce a fever to control infections. Answer: B. Tumor necrosis factor (TNF), Interleukin-1 (IL-1), and Interleukin-6 (IL-6) are responsible for fever activation. 8. What are the classical signs of inflammation? OA. Heat, redness, swelling, pain, and loss of function are classical signs of inflammation. B. Coughing, nausea, fatigue, chills, and loss of appetite are classical signs of inflammation. - C. Dizziness, headaches, fever, sweating, and weight loss are classical signs of inflammation. D. Itching, rash, coughing, dizziness, and joint pain are classical signs of inflammation. - Answer: A. Heat, redness, swelling, pain, and loss of function are classical signs of inflammation.  9. What is histamine, and what does the innate immune system use it for? A. Histamine is a hormone that signals muscle contraction to fight pathogens in tissues. OB. Histamine is a chemical released by immune cells that causes vasodilation and increases blood flow to infection sites. C. Histamine is an enzyme that digests pathogens after they are engulfed by immune cells. D. Histamine is a protein that binds to pathogens and neutralizes them, preventing the spread of infection. Answer: B. Histamine is a chemical released by immune cells that causes vasodilation and increases blood flow to infection sites. 10. What are kinins, and what does the innate immune system use them for? * A. Kinins are enzymes that destroy bacterial cell walls to prevent infection. B. Kinins are molecules that increase capillary permeability and promote inflammation to allow immune cells to access infection sites. C. Kinins are proteins that bind to pathogens, marking them for destruction by antibodies. D. Kinins are hormones that reduce inflammation and help tissues repair faster after injury. Answer: B. Kinins are molecules that increase capillary permeability and promote inflammation to allow immune cells to access infection sites. LECTURE 6 1. What is the adaptive immune system? so A. The adaptive immune system is a specific defense mechanism that develops long-term immunity through memory cells. -B. The adaptive immune system is a general defense that reacts to all pathogens the same way each time. C. The adaptive immune system produces enzymes that break down toxins released by pathogens. -D. The adaptive immune system responds quickly to pathogens without developing any memory. Answer: A. The adaptive immune system is a specific defense mechanism that develops long-term immunity through memory cells. 2. What are the phases of the adaptive immune response? A. Recognition, amplification, and destruction are the phases of the adaptive immune response. * o B. Initiation, engagement, and memory are the phases of the adaptive immune response.  C. Recognition, activation, and attack are the phases of the adaptive immune response. D. Sensitization, response, and neutralization are the phases of the adaptive immune response. Answer: C. Recognition, activation, and attack are the phases of the adaptive immune response. 3. What events occur during the activation phase of the adaptive immune response? O A. Immune cells rapidly divide, increase in number, and begin producing antibodies to target pathogens. B. Pathogens are engulfed by neutrophils, and macrophages release enzymes to digest them. C. Blood vessels constrict, reducing the spread of pathogens throughout the body. D. Memory cells are formed to provide long-term immunity without any further immune response. Answer: A. Immune cells rapidly divide, increase in number, and begin producing antibodies to target pathogens. 4. What events occur during the attack phase of the adaptive immune response? A. The immune system creates memory cells for future defense and restores homeostasis. O B. Activated immune cells neutralize, kill, or remove pathogens through cellular and humoral responses. C. Antigens are recognized, and the immune system prepares for the next phase of defense. I D. Blood clotting occurs, and tissues regenerate to close any wounds caused by the infection. Answer: B. Activated immune cells neutralize, kill, or remove pathogens through cellular and humoral responses. 5. Where are lymphoid tissues found in the body? A. Lymphoid tissues are found in the brain, liver, and kidneys, where they store immune cells for & quick responses. O B. Lymphoid tissues are found in the skin, spleen, and mucous membranes of the digestive and respiratory tracts. C. Lymphoid tissues are located in the muscles, bones, and joints, where they help regulate - immune responses. D. Lymphoid tissues are found only in the circulatory system, helping transport immune cells. Answer: B. Lymphoid tissues are found in the skin, spleen, and mucous membranes of the digestive and respiratory tracts.  thymus a bone marrow 6. What are primary lymphatic organs, and what are their purposes? A. Primary lymphatic organs, such as the lymph nodes and spleen, filter blood and remove - pathogens. B. Primary lymphatic organs, like the thymus and bone marrow, produce and mature lymphocytes. C. Primary lymphatic organs, such as the tonsils and adenoids, trap pathogens and prevent - them from spreading. D. Primary lymphatic organs, like the appendix and liver, help store immune cells for future use. - Answer: B. Primary lymphatic organs, like the thymus and bone marrow, produce and mature lymphocytes. 7. What are secondary lymphatic organs, and what are their purposes? O A. Secondary lymphatic organs, like the spleen and lymph nodes, filter pathogens and activate immune cells. B. Secondary lymphatic organs, such as the liver and kidneys, store antigens and release antibodies. I C. Secondary lymphatic organs, including the thymus and bone marrow, create and train T-cells and B-cells. D. Secondary lymphatic organs, like the appendix and stomach, digest pathogens and help regulate immune responses. Answer: A. Secondary lymphatic organs, like the spleen and lymph nodes, filter pathogens and activate immune cells. 8. What is the primary function of lymph nodes? A. Lymph nodes store immune cells for quick deployment in case of infection. * B. Lymph nodes filter lymph fluid and trap pathogens for destruction by immune cells. C. Lymph nodes produce antibodies and release them into the bloodstream to neutralize pathogens. D. Lymph nodes secrete hormones that regulate immune responses throughout the body. Answer: B. Lymph nodes filter lymph fluid and trap pathogens for destruction by immune cells. 9. What is the reticuloendothelial system? O A. The reticuloendothelial system is a network of tissues and cells that filter and destroy pathogens throughout the body. B. The reticuloendothelial system is a system of enzymes that break down cellular waste products after infection. - C. The reticuloendothelial system is a group of neurons that regulate immune responses in the  brain. D. The reticuloendothelial system is a collection of blood vessels that transport immune cells to infection sites. Answer: A. The reticuloendothelial system is a network of tissues and cells that filter and destroy pathogens throughout the body. * 10. What are the three major pathways used by the reticuloendothelial system to trap foreign antigens? A. The classical pathway, lectin pathway, and alternative pathway are the major pathways of the system. B. The vascular pathway, cytokine pathway, and phagocytic pathway are the major pathways of the system. O C. The complement pathway, opsonization pathway, and chemokine pathway are the major pathways of the system. D. The clotting pathway, inflammation pathway, and antigen-presenting pathway are the major pathways of the system. Answer: A. The classical pathway, lectin pathway, and alternative pathway are the major pathways of the system. LECTURE 7 1. Where do B-cells develop? How are B-cells activated? O A. B-cells develop in the bone marrow and are activated by binding to specific antigens and receiving signals from helper T-cells. B. B-cells develop in the thymus and are activated by recognizing self-antigens on infected - cells. I C. B-cells develop in the spleen and are activated by cytokines released by macrophages. D. B-cells develop in the lymph nodes and are activated by binding to T-cell receptors. Answer: A. B-cells develop in the bone marrow and are activated by binding to specific antigens and receiving signals from helper T-cells. 2. What role do B-cells play in a humoral immune response? A. B-cells directly attack infected cells and destroy pathogens through phagocytosis. ⑳B. B-cells produce antibodies that bind to and neutralize antigens in the blood and lymph. C. B-cells present antigens to T-cells to trigger a cell-mediated immune response. D. B-cells release histamines to increase inflammation at the site of infection.  Answer: B. B-cells produce antibodies that bind to and neutralize antigens in the blood and lymph. 3. What type of B-cells do mature, naïve B-cells become after activation? A. Mature, naïve B-cells become helper T-cells and initiate the immune response. ⑳ B. Mature, naïve B-cells become plasma cells, which produce large amounts of antibodies. C. Mature, naïve B-cells become macrophages and help remove dead cells. D. Mature, naïve B-cells become dendritic cells and present antigens to other immune cells. Answer: B. Mature, naïve B-cells become plasma cells, which produce large amounts of antibodies. 4. How are memory B-cells generated? A. Memory B-cells are generated by somatic hypermutation, which allows B-cells to randomly - produce new antibodies after each infection. ⑧ B. Memory B-cells are generated when activated B-cells differentiate into long-lived cells that remain in the body for future responses. C. Memory B-cells are generated by exposure to pathogens that bind to the B-cell receptors on inactive immune cells. D. Memory B-cells are generated when B-cells encounter foreign antigens for the second time and produce immediate responses. Answer: B. Memory B-cells are generated when activated B-cells differentiate into long-lived cells that remain in the body for future responses. 5. What is the primary function of memory B-cells in the immune response? A. The primary function of memory B-cells is to present antigens to T-cells, initiating a rapid - immune response. B. The primary function of memory B-cells is to act as regulatory cells, preventing overactive immune responses. O C. The primary function of memory B-cells is to store antigen-specific information and respond quickly to future infections. D. The primary function of memory B-cells is to produce cytokines and trigger inflammation at - the infection site. Answer: C. The primary function of memory B-cells is to store antigen-specific information and respond quickly to future infections. 6. What components comprise a B-cell receptor (BCR)? O A. A B-cell receptor is made of light chains, heavy chains, and a variable region that binds to antigens. B. A B-cell receptor consists of alpha and beta chains that bind to the antigen-presenting cells. C. A B-cell receptor is composed of cytokines, chemokines, and an antigen-binding region. D. A B-cell receptor is composed of lipids, carbohydrates, and a recognition site for pathogens. Answer: A. A B-cell receptor is made of light chains, heavy chains, and a variable region that binds to antigens. 7. How does a BCR recognize an antigen? A. A BCR recognizes an antigen by engulfing it and breaking it down into smaller fragments for ⑤ T-cells. B. A BCR recognizes an antigen by binding to specific epitopes on the antigen's surface through its variable region. C. A BCR recognizes an antigen by secreting enzymes that degrade the antigen, exposing - hidden recognition sites. - D. A BCR recognizes an antigen by producing cytokines that attract other immune cells to the pathogen. Answer: B. A BCR recognizes an antigen by binding to specific epitopes on the antigen's surface through its variable region. 8. What is somatic recombination, and why is it important for B-cells? O A. Somatic recombination allows B-cells to generate diverse antigen receptors by rearranging their DNA during development. B. Somatic recombination enables B-cells to produce enzymes that break down harmful - pathogens after they bind to antibodies. C. Somatic recombination is the process where B-cells change their structure to become - macrophages in response to infection. D. Somatic recombination allows B-cells to multiply and produce large quantities of cytokines to - aid in immune defense. Answer: A. Somatic recombination allows B-cells to generate diverse antigen receptors by rearranging their DNA during development.  LECTURE 8 - T cell/cellular 1. What are CD4+ T-cells, and what role do they play in an immune response? - A) They are cytotoxic cells that directly kill infected cells. B) They are regulatory cells that suppress immune activity. O C) They are helper cells that coordinate immune responses. D) They are memory cells that store antigen information. Answer: C) They are helper cells that coordinate immune responses. 2. What are CD8+ T-cells, and what role do they play in an immune ↑ response? Ball/numoral A) They are regulatory cells that suppress immune activity. B) They are helper cells that coordinate immune responses. & C) They are memory cells that store antigen information. D) They are cytotoxic cells that directly kill infected cells. Answer: D) They are cytotoxic cells that directly kill infected cells. 3. What are regulatory T-cells, and what role do they play in an immune response? A) They are cytotoxic cells that directly kill infected cells. B) They are helper cells that coordinate immune responses. C) They are memory cells that store antigen information. O D) They are regulatory cells that suppress immune activity. Answer: D) They are regulatory cells that suppress immune activity. 4. What are memory T-cells, and what role do they play in an immune response? A) They are helper cells that coordinate immune responses. - B) They are cytotoxic cells that directly kill infected cells.  g C) They are memory cells that store antigen information. D) They are regulatory cells that suppress immune activity. Answer: C) They are memory cells that store antigen information. 5. How are T-cells activated? o A) By direct contact with antibodies. B) By recognizing antigens presented by other immune cells. C) By secreting cytokines. D) By suppressing immune responses. Answer: B) By recognizing antigens presented by other immune cells. 6. What cytokines induce activated T-cells to differentiate into the different * types of T-cells? A) IL-2 and IL-4. B) TNF-α and IL-10. C) IL-1 and IL-8. D) Interferons and chemokines. Answer: A) IL-2 and IL-4. 7. What is the purpose of positive selection in T-cell development? A) To ensure T-cells recognize self-antigens. * B) To eliminate T-cells that are non-functional. C) To promote T-cells that can recognize foreign antigens. D) To suppress immune activity. Answer: C) To promote T-cells that can recognize foreign antigens. 8. What is the purpose of negative selection in T-cell development? O A) To eliminate T-cells that recognize self-antigens. B) To suppress the immune response.  C) To promote T-cells that recognize foreign antigens. D) To enhance cytokine production. Answer: A) To eliminate T-cells that recognize self-antigens. # 9. What is the primary function of a TCR? A) To recognize and bind to antigens presented by other cells. g B) To secrete cytokines that stimulate immune cells. C) To activate cytotoxic cell killing. D) To suppress immune responses. Answer: A) To recognize and bind to antigens presented by other cells. 10. How does a TCR recognize an antigen? A) By binding to antigens directly in the blood. OB) By binding to antigens presented by MHC molecules on other cells. C) By receiving signals from B-cells. D) By producing antibodies. Answer: B) By binding to antigens presented by MHC molecules on other cells. V(D)J recome 11. What is somatic recombination, and why is it important for T-cells? A) It allows the TCR to secrete cytokines. O B) It is the process by which the TCR diversity is generated. C) It helps T-cells recognize self-antigens. D) It eliminates T-cells that recognize foreign antigens. Answer: B) It is the process by which the TCR diversity is generated. LECTURE 9 1. What are the classes of major histocompatibility complex (MHC)?  A) MHC Class A and MHC Class B O B) MHC Class I and MHC Class II C) MHC Class C and MHC Class D D) MHC Class III and MHC Class IV Answer: B) MHC Class I and MHC Class II 2. What roles do the various MHC molecule classes play in the adaptive * immune response (in particular with T-cells)? A) MHC Class I presents to helper T-cells, while MHC Class II presents to cytotoxic T-cells. B) MHC Class I presents to cytotoxic T-cells, while MHC Class II presents to helper T-cells. C) MHC Class I and II both present to regulatory T-cells. YD) MHC Class I and II both present to memory T-cells. Answer: B) MHC Class I presents to cytotoxic T-cells, while MHC Class II presents to helper T-cells. 3. How do MHC molecules bind to antigen peptides? A) By secreting cytokines that interact with antigen receptors. TB) By capturing free-floating antigens in the bloodstream. C) By binding peptides processed and presented by antigen-presenting cells. D) By producing antibodies that adhere to the antigen. Answer: C) By binding peptides processed and presented by antigen-presenting cells. 4. What type of T-cell interacts with MHC class I molecules? A) Helper T-cells O B) Cytotoxic T-cells C) Memory T-cells D) Regulatory T-cells Answer: B) Cytotoxic T-cells 5. What type of T-cell interacts with MHC class II molecules?  O A) Helper T-cells B) Cytotoxic T-cells C) Memory T-cells D) Regulatory T-cells Answer: A) Helper T-cells 6. What is the primary function of MHC molecules? A) To store antigen information for future use. O B) To present antigen peptides to T-cells for immune recognition. C) To produce cytokines that activate immune cells. D) To destroy infected cells directly. Answer: B) To present antigen peptides to T-cells for immune recognition. 7. How are MHC genes inherited? How are they expressed? * A) MHC genes are inherited dominantly and expressed codominantly. B) MHC genes are inherited recessively and expressed randomly. C) MHC genes are inherited randomly and expressed dominantly. D) MHC genes are inherited codominantly and expressed recessively. Answer: A) MHC genes are inherited dominantly and expressed codominantly. 8. How many MHC genes for classes I and II can be expressed on the surface of a cell at a time? ↑ A) One MHC gene for Class I and one MHC gene for Class II B) Three MHC genes for Class I and three MHC genes for Class II C) Two MHC genes for Class I and four MHC genes for Class II D) Six MHC genes for Class I and six MHC genes for Class II Answer: D) Six MHC genes for Class I and six MHC genes for Class II LECTURE 10 1. Why do T-cells need two signals before activating? A) To ensure they only activate when antigen is present and prevent autoimmunity. B) To regulate cytokine production and increase antibody production. C) To decrease the risk of cell-mediated responses and lower immune memory. D) To enhance B-cell interactions and promote faster TCR recombination. Answer: A) To ensure they only activate when antigen is present and prevent autoimmunity. 2. What are the two signals needed for T-cell activation? A) TCR binding to antigen and cytokine release by B-cells. B) TCR binding to antigen and costimulatory molecule interaction. C) Cytokine release by macrophages and TCR binding to antigens. D) Cytokine release by helper T-cells and interaction with MHC. Answer: B) TCR binding to antigen and costimulatory molecule interaction. 3. What are the effector functions of CD4+ T-cells? A) Killing infected cells and secreting antibodies to neutralize pathogens. B) Regulating immune response and activating other immune cells like macrophages. C) Destroying infected body cells and stimulating memory T-cell formation. D) Presenting antigens to B-cells and binding to MHC Class II molecules. Answer: B) Regulating immune response and activating other immune cells like macrophages. 4. What roles do CD4+ T-cells play in humoral and cell-mediated immunity? A) They activate B-cells in humoral immunity and stimulate cytotoxic T-cells in cell-mediated immunity. B) They produce antibodies in humoral immunity and kill infected cells in cell-mediated immunity. C) They kill infected cells in humoral immunity and activate TCR recombination in cell-mediated immunity. D) They suppress B-cells in humoral immunity and stimulate apoptosis in cell-mediated immunity. Answer: A) They activate B-cells in humoral immunity and stimulate cytotoxic T-cells in cell-mediated immunity. 5. What is the primary function of cytotoxic T-cells in cell-mediated immunity? A) To regulate helper T-cells and produce antibodies against pathogens. B) To kill infected cells by releasing cytotoxic granules and triggering apoptosis. C) To stimulate memory T-cells and release cytokines that promote B-cell activity. D) To suppress immune responses by deactivating effector T-cells and macrophages. Answer: B) To kill infected cells by releasing cytotoxic granules and triggering apoptosis. 6. How do cytotoxic T-cells kill infected body cells? A) By producing antibodies that neutralize pathogens. B) By releasing cytotoxic granules and inducing cell death via apoptosis. C) By activating helper T-cells to produce cytokines and kill the cell. D) By binding to antigen-presenting cells and enhancing antigen clearance. Answer: B) By releasing cytotoxic granules and inducing cell death via apoptosis. LECTURE 11 1. What is an immunogen? A) A molecule that stimulates cytokine production and immune cell differentiation. B) A substance capable of inducing an immune response and generating memory cells. C) A protein that inhibits antigen recognition by immune cells and limits immunity. D) A substance that directly kills pathogens and prevents future infections. Answer: B) A substance capable of inducing an immune response and generating memory cells. 2. How can an immunogen induce an immune response? A) By binding directly to antibodies and releasing cytokines. B) By binding to immune cells and being presented by MHC molecules. C) By producing memory cells and interacting with regulatory proteins. D) By activating B-cells and suppressing T-cell function. Answer: B) By binding to immune cells and being presented by MHC molecules. 3. How can an immunogen generate immunological memory? A) By inducing rapid cytokine production and stimulating T-cell apoptosis. B) By stimulating memory B-cells and T-cells that respond faster upon re-exposure. C) By generating long-lasting antibodies that continuously activate helper T-cells. D) By interacting with regulatory T-cells to suppress future immune responses. Answer: B) By stimulating memory B-cells and T-cells that respond faster upon re-exposure. 4. What are the four characteristics that increase the immunogenicity of an antigen? A) Large size, chemical complexity, high molecular weight, and low antigen concentration. B) Large size, foreignness, chemical complexity, and proper degradability. C) Small size, low molecular weight, chemical simplicity, and self-origin. D) Small size, foreignness, high concentration, and rapid degradation. Answer: B) Large size, foreignness, chemical complexity, and proper degradability. 5. How do these four characteristics increase the immunogenicity of an antigen? A) By making the antigen easier to degrade and less recognizable by immune cells. B) By allowing the antigen to bypass immune detection and suppress immune memory. C) By making the antigen more easily recognized and effectively processed by the immune system. D) By enhancing antigen tolerance and reducing the likelihood of immune response. Answer: C) By making the antigen more easily recognized and effectively processed by the immune system. 6. What is a primary immunogenic response? What is a secondary immunogenic response? A) Primary occurs with rapid antibody production; secondary has delayed memory activation. B) Primary is the first exposure to an antigen; secondary is a stronger, faster response upon re-exposure. C) Primary involves memory T-cell formation; secondary involves B-cell suppression and antigen clearance. D) Primary involves immediate cell death; secondary involves long-term cytokine secretion. Answer: B) Primary is the first exposure to an antigen; secondary is a stronger, faster response upon re-exposure. 7. What are thymus-dependent antigens (TD antigens), and how do they activate B-cells only with the help of T-cells? A) TD antigens require antigen-presenting cells to stimulate T-cells, which in turn activate B-cells. B) TD antigens stimulate B-cells directly, causing them to differentiate without T-cell help. C) TD antigens rely on cytokines produced by macrophages to interact with B-cells. D) TD antigens bypass helper T-cells and activate memory B-cells through antigen presentation. Answer: A) TD antigens require antigen-presenting cells to stimulate T-cells, which in turn activate B-cells. LECTURE 12 1. What is an antigen? A) A protein that neutralizes toxins and destroys pathogens. B) A molecule that can be recognized by the immune system and trigger a response. C) A molecule that suppresses immune responses and inhibits cell activation. D) A cytokine that activates macrophages and enhances phagocytosis. Answer: B) A molecule that can be recognized by the immune system and trigger a response. 2. What are the different types of antigens? A) Self-antigens, heterologous antigens, and bacterial toxins. B) Foreign antigens, self-antigens, and immunosuppressive antigens. C) Self-antigens, foreign antigens, and tumor antigens. D) Foreign antigens, toxoids, and immunogenic antigens. Answer: C) Self-antigens, foreign antigens, and tumor antigens. 3. How do the different types of antigens elicit an immune response? A) Foreign antigens trigger an immune response, while self-antigens do not unless altered. B) Tumor antigens activate B-cells, while self-antigens always trigger a strong response. C) Foreign antigens only suppress immune cells, and tumor antigens prevent immune memory. D) Self-antigens produce antibodies, while foreign antigens are tolerated by the body. Answer: A) Foreign antigens trigger an immune response, while self-antigens do not unless altered. 4. What is an epitope? A) A fragment of an antibody that binds to antigens during immune reactions. B) The specific part of an antigen that is recognized and bound by an antibody or T-cell receptor. C) A cytokine that enhances antigen recognition and amplifies immune responses. D) A protein on T-cells that binds to self-antigens and initiates immune tolerance. Answer: B) The specific part of an antigen that is recognized and bound by an antibody or T-cell receptor. 5. How do epitopes interact with antibodies and T-cell receptors? A) Epitopes activate B-cells directly and promote cytokine release by antibodies. B) Epitopes bind to antibodies and T-cell receptors, which activate immune cells. C) Epitopes inhibit antigen presentation and block antibody production by T-cells. D) Epitopes bind to memory cells and prevent future antigen recognition. Answer: B) Epitopes bind to antibodies and T-cell receptors, which activate immune cells. 6. What is cross-reactivity, and how can it activate an immune response? A) It occurs when two different antigens share epitopes, causing immune cells to recognize and react to both. B) It occurs when antigens from the same pathogen trigger the production of different types of antibodies. C) It involves antigen suppression, where B-cells are activated to block immune memory. D) It involves the production of cytokines that inhibit T-cell receptor binding to similar antigens. Answer: A) It occurs when two different antigens share epitopes, causing immune cells to recognize and react to both. 7. What is a toxin? What is a toxoid? A) A toxin is a substance that enhances immune responses, and a toxoid is a molecule that inhibits immunity. B) A toxin is a harmful substance produced by pathogens, and a toxoid is an inactivated form of a toxin used in vaccines. C) A toxin is a neutral protein that activates T-cells, and a toxoid is a chemical that enhances antigen presentation. D) A toxin is a harmful protein that inhibits antibodies, and a toxoid is a protein that amplifies immune responses. Answer: B) A toxin is a harmful substance produced by pathogens, and a toxoid is an inactivated form of a toxin used in vaccines. LECTURE 13 1. What is the basic structure of an immunoglobulin? A) Two light chains and two heavy chains connected by disulfide bonds. B) Two heavy chains and two variable regions forming antigen-binding sites. C) Four heavy chains forming constant regions and antigen recognition sites. D) Two light chains and two constant regions connected by peptide bonds. Answer: A) Two light chains and two heavy chains connected by disulfide bonds. 2. What is the purpose of the variable regions of an immunoglobulin? A) To bind to antigens and determine the antibody’s specificity. B) To bind to other immune cells and stimulate cytokine release. C) To regulate the immune response and control antibody production. D) To trigger apoptosis in infected cells and release immune signals. Answer: A) To bind to antigens and determine the antibody’s specificity. 3. What is the purpose of the constant regions of an immunoglobulin? A) To bind to antigens and initiate T-cell responses. B) To interact with immune cells and determine the antibody’s class. C) To neutralize pathogens and prevent them from entering cells. D) To bind to B-cells and stimulate memory cell production. Answer: B) To interact with immune cells and determine the antibody’s class. 4. What are the primary functions of antibodies? A) To bind pathogens and signal immune cells to neutralize or destroy them. B) To activate complement proteins and suppress the immune response. C) To produce cytokines and promote the proliferation of B-cells. D) To generate memory T-cells and stimulate antigen presentation. Answer: A) To bind pathogens and signal immune cells to neutralize or destroy them. 5. What are the different classes of antibodies, and how do they each function? A) IgA, IgG, IgM, IgE, and IgD; each class has specific roles in immune responses. B) IgE, IgD, IgM, and IgG; they each bind to the same antigen to activate B-cells. C) IgA, IgM, IgE, and IgD; each class is involved in the activation of helper T-cells. D) IgA, IgG, IgE, and IgD; they produce cytokines and help with antigen clearance. Answer: A) IgA, IgG, IgM, IgE, and IgD; each class has specific roles in immune responses. 6. Where are the different classes of antibodies predominantly found throughout the body? A) IgA in mucosal areas, IgG in the bloodstream, IgE in tissues, and IgM in plasma. B) IgE in mucosal areas, IgG in lymph nodes, IgA in the liver, and IgM in the spleen. C) IgG in mucosal areas, IgA in the bloodstream, IgM in tissues, and IgE in plasma. D) IgA in tissues, IgM in the bloodstream, IgG in plasma, and IgE in mucosal areas. Answer: A) IgA in mucosal areas, IgG in the bloodstream, IgE in tissues, and IgM in plasma. 7. What are the functions of IgG antibodies? A) To neutralize pathogens, activate complement, and facilitate opsonization. B) To bind to infected cells and trigger apoptosis through T-cell activation. C) To activate B-cells, inhibit T-cell proliferation, and release cytokines. D) To stimulate helper T-cells, promote antigen presentation, and trigger cell death. Answer: A) To neutralize pathogens, activate complement, and facilitate opsonization. 8. Where are IgG antibodies predominantly found? A) In mucosal secretions such as tears and saliva. B) In the bloodstream and extracellular fluid. C) In tissues near lymph nodes and spleen. D) In bone marrow and thymus for immune regulation. Answer: B) In the bloodstream and extracellular fluid. LECTURE 14 1. What are the functions of IgM antibodies? A) To act as the first antibody produced in response to an infection and activate complement. B) To bind to allergens, activate eosinophils, and neutralize toxins. C) To neutralize pathogens and suppress T-cell activity. D) To stimulate helper T-cells and produce cytokines for immune regulation. Answer: A) To act as the first antibody produced in response to an infection and activate complement. 2. How does IgM activate the complement system? A) By binding to complement receptors and triggering phagocytosis of pathogens. B) By binding to antigens and creating a complex that recruits complement proteins. C) By neutralizing pathogens and stimulating cytokine production by macrophages. D) By releasing cytokines that initiate the complement cascade and enhance opsonization. Answer: B) By binding to antigens and creating a complex that recruits complement proteins. 3. What are the functions of IgA antibodies? A) To protect mucosal surfaces by neutralizing pathogens and preventing their entry. B) To activate complement, neutralize toxins, and promote cell-mediated immunity. C) To bind to allergens and trigger eosinophil-mediated destruction of pathogens. D) To regulate immune responses and enhance phagocytosis by macrophages. Answer: A) To protect mucosal surfaces by neutralizing pathogens and preventing their entry. 4. Where are IgA antibodies predominantly found? A) In the bloodstream and lymphatic system. B) In mucosal areas such as the respiratory and gastrointestinal tracts. C) In tissues surrounding lymph nodes and the spleen. D) In bone marrow and thymus for immune regulation. Answer: B) In mucosal areas such as the respiratory and gastrointestinal tracts. 5. Where are IgD antibodies predominantly found? A) In the thymus and bone marrow, where they interact with T-cells. B) On the surface of immature B-cells, primarily in the respiratory system. C) In the bloodstream and lymph nodes, binding to pathogens and stimulating B-cells. D) On the surface of mature B-cells, where they assist in antigen recognition. Answer: D) On the surface of mature B-cells, where they assist in antigen recognition. 6. How do IgD antibodies help eliminate self-reactive B-cells? A) By binding to autoantigens and signaling for the B-cell to undergo apoptosis. B) By activating macrophages to destroy self-reactive B-cells. C) By suppressing immune responses and preventing the production of antibodies. D) By enhancing antigen presentation to T-cells and promoting immune tolerance. Answer: A) By binding to autoantigens and signaling for the B-cell to undergo apoptosis. LECTURE 15 1. What are the functions of IgE antibodies? A) To bind allergens and parasites, triggering mast cell and basophil degranulation. B) To neutralize toxins, activate complement, and enhance phagocytosis. C) To stimulate B-cell proliferation and produce memory T-cells. D) To bind to bacteria and viruses, initiating opsonization and antigen presentation. Answer: A) To bind allergens and parasites, triggering mast cell and basophil degranulation. 2. Where are IgE antibodies predominantly found? A) In the bloodstream and mucosal tissues of the respiratory and gastrointestinal tracts. B) On the surface of mast cells and basophils in tissues exposed to the external environment. C) In the bone marrow, spleen, and lymph nodes, regulating immune responses. D) In the central nervous system and circulating lymphatic tissues. Answer: B) On the surface of mast cells and basophils in tissues exposed to the external environment. 3. What is isotype switching, and how does it occur? A) Isotype switching is the process by which B-cells change the class of antibodies they produce, triggered by signals from helper T-cells and cytokines. B) Isotype switching is the exchange of variable regions in antibodies, occurring when antigens bind to the antibody's constant region. C) Isotype switching occurs when antibodies change their affinity for antigens and is regulated by memory T-cells. D) Isotype switching allows B-cells to alter their antigen specificity, driven by changes in antigen structure. Answer: A) Isotype switching is the process by which B-cells change the class of antibodies they produce, triggered by signals from helper T-cells and cytokines. 4. How do cytokines regulate the production of different antibody classes? A) By binding to T-cell receptors and triggering B-cell suppression in the bone marrow. B) By activating B-cells to produce specific antibodies depending on the type of pathogen and infection site. C) By stimulating macrophages to induce B-cell apoptosis and reduce antigen binding. D) By promoting B-cell migration to the lymph nodes and increasing antigen recognition. Answer: B) By activating B-cells to produce specific antibodies depending on the type of pathogen and infection site. 5. How are antibodies produced? A) B-cells produce antibodies after recognizing antigens and receiving activation signals from helper T-cells. B) Macrophages produce antibodies in response to cytokine release by neutrophils and natural killer cells. C) Antibodies are produced by T-cells that recognize pathogens and trigger B-cell proliferation. D) B-cells produce antibodies only in the thymus and spleen after cytokine activation. Answer: A) B-cells produce antibodies after recognizing antigens and receiving activation signals from helper T-cells. 6. What is somatic recombination? Gene conversion? Hypermutation? A) Somatic recombination creates antigen receptor diversity; gene conversion adds DNA segments; hypermutation changes the affinity of antibodies for antigens. B) Somatic recombination generates memory cells; gene conversion destroys faulty cells; hypermutation repairs DNA in immune cells. C) Somatic recombination suppresses T-cell proliferation; gene conversion modifies B-cell receptors; hypermutation prevents autoimmune diseases. D) Somatic recombination produces cytokines; gene conversion activates T-cells; hypermutation triggers cell death in self-reactive cells. Answer: A) Somatic recombination creates antigen receptor diversity; gene conversion adds DNA segments; hypermutation changes the affinity of antibodies for antigens. 7. How is the diversity of antigen receptors on B and T-cells generated? A) By somatic recombination, junctional diversity, and somatic hypermutation during immune cell development. B) By cytokine activation, clonal expansion, and apoptosis of self-reactive cells in the thymus. C) By random recombination of constant regions and antigen-driven gene suppression in lymphocytes. D) By activating complement proteins and suppressing antibody production in immune cells. Answer: A) By somatic recombination, junctional diversity, and somatic hypermutation during immune cell development.