Lesson 6.4.2
6.4.2 B cells and T cells Quiz: Pearson Edexcel Biology A (Salters-Nuffield), Unit 6
20 questions
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Lesson 6.4.2, B cells and T cells: 20 multiple choice questions for the Pearson Edexcel Biology A (Salters-Nuffield) (9BI0), Unit 6: Immunity, Infection and Forensics, written with Revision Ninja.
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The 20 questions
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Which cells mature in the bone marrow before entering the blood?
- Macrophages, which mature in the bone marrow and then enter the blood as mature cells
- Neutrophils, which mature in the thymus and then migrate to the lymph nodes
- T cells, which mature in the bone marrow and then migrate to the spleen to be activated
- B cells, which mature in the bone marrow and carry antigen-specific receptors on their surface
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Where do T cells mature before they enter the circulation?
- The spleen, where lymphocytes are activated after antigen recognition
- The thymus
- The lymph nodes, where antigens are first presented to naive lymphocytes
- The bone marrow, where all blood cells are formed and matured
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Helper T cells are identified by which surface marker?
- CD4
- CD34, which is found on haemopoietic stem cells in the bone marrow
- CD8, which is found on killer T cells and recognises MHC class I molecules
- CD19, which is found on B cells and acts as a co-receptor for antigen binding
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Killer T cells recognise infected cells by:
- Detecting antibodies that are bound to the surface of the infected cell membrane
- Detecting antigen presented on MHC class I molecules on the surface of the infected cell
- Detecting lysozyme that has been secreted by the infected cell into the extracellular fluid
- Detecting histamine that is released by the infected cell during inflammation
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Which action is carried out by cytotoxic (killer) T cells?
- Engulfing infected cells and digesting them within phagolysosomes in the lymph nodes
- Secreting large amounts of antibody into the blood to neutralise free viruses
- Releasing histamine that causes vasodilation and increases the permeability of capillaries
- Inducing apoptosis in infected or abnormal cells, often by releasing perforin and granzymes
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Which cells differentiate into plasma cells after activation by antigen and helper T cell signals?
- Helper T cells, which secrete antibodies and also release cytokines to stimulate B cells
- Memory T cells, which secrete antibodies immediately on re-exposure to an antigen
- B effector cells, which secrete large quantities of antibody
- Killer T cells, which secrete antibodies and release perforin to kill infected cells
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Memory B cells and memory T cells are important because they:
- Persist after the infection and mount a faster and larger response when the same antigen is encountered again
- Are short-lived and die within a few days, so they provide protection only during the first infection
- Produce antibodies continuously for the rest of the person's life, even without exposure to any antigen
- Attack the body's own cells, which prevents the immune system from becoming overactive
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Which statement describes the clonal selection of B cells correctly?
- B cells are selected by helper T cells, which then secrete antibody directly from the bone marrow
- All B cells are activated by any antigen, which causes them all to divide in identical numbers
- A B cell whose receptor matches an antigen is selected, then divides to produce many clones of plasma and memory cells
- A B cell is selected only if it is infected with a virus, and then it divides into killer T cells
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What is the role of helper T cells in the activation of killer T cells?
- They release cytokines that stimulate killer T cells to divide and become active
- They inhibit killer T cells so that the body does not destroy its own tissues
- They secrete antibodies that bind to the killer T cells and make them more specific
- They engulf the infected cells and present their antigens to killer T cells directly
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A person is infected for the second time with the same virus. Why is the second response usually faster and stronger?
- The antibodies from the first infection are released from the spleen only on the second exposure
- Memory B and T cells are already present, so clonal expansion starts quickly and produces antibody sooner
- The virus has lost its antigens after the first infection, so it is less able to cause symptoms
- Killer T cells are produced from the bone marrow only after each infection, so they are faster the second time
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Which feature distinguishes B cells from T cells in the body's immune response?
- B cells kill infected cells directly, whereas T cells secrete antibody into the blood
- B cells carry CD8 markers, whereas T cells carry CD19 markers on their membrane
- B cells secrete antibodies after activation, whereas T cells act through cell contact or cytokine signalling
- B cells mature in the thymus, whereas T cells mature in the bone marrow
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A patient has a deficiency in helper T cells. Which consequence is most likely?
- Reduced activation of B cells and killer T cells
- Increased destruction of red blood cells, because helper T cells normally protect them from antibodies
- Increased antibody production, because helper T cells normally suppress B cell division
- No effect on the immune response, because killer T cells can work independently of helper T cells
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Which statement evaluates the claim that B cells alone are sufficient to defeat an infection?
- The claim is accurate, since B cells produce antibodies that destroy all pathogens on contact
- The claim is inaccurate, since B cells need T helper signals to fully activate and T killer cells are required for infected cells
- The claim is inaccurate only for bacteria, since B cells are sufficient against every viral infection
- The claim is accurate, since B cells can kill infected cells directly without any other cell types
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Which statement about the clonal expansion of T cells is accurate?
- T cells do not divide after activation, so they remain at a fixed number in the blood
- T cells divide only in the thymus, so their clones never reach the site of infection
- After antigen recognition, the T cell divides to produce many clones, some of which become memory cells
- T cells expand only if they are not presented with an antigen, which keeps the population stable
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Which cells are the main effectors of the cell-mediated immune response?
- Plasma cells, which secrete antibody into the blood in very large quantities
- Mast cells, which release histamine and dilate blood vessels at the site of damage
- Killer T cells, which destroy infected or abnormal cells directly
- Macrophages and neutrophils, which engulf and digest pathogens in the tissues
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A B cell clone divides once every 6 hours. How many cells are produced from one cell after 24 hours if every daughter cell keeps dividing?
- 24 cells, since one new cell forms every hour and the population grows linearly
- 16 cells, since there are four doublings in 24 hours
- 4 cells, since 24 divided by 6 gives four and each division adds exactly one new cell
- 64 cells, since the population doubles three times after each six-hour interval
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Helper T cells stimulate the division of B cells and killer T cells by releasing:
- Cytokines, such as interleukin-2, which act as signals to drive lymphocyte proliferation
- Lysozyme, which hydrolyses peptidoglycan in the cell walls of bacteria at the site of infection
- Perforin, which forms pores in the membranes of infected cells and causes their lysis
- Histamine, which dilates blood vessels at the site of infection and increases permeability
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A B cell receptor binds its specific antigen. Which sequence best describes the subsequent process?
- Engulfment and digestion of the antigen in lysosomes, followed by its presentation on MHC class I
- Conversion into a killer T cell, which then attacks the antigen directly in the lymph nodes
- Immediate release of perforin, which destroys the antigen before any cloning can occur
- Activation with helper T cell signals, then clonal expansion and differentiation into plasma and memory cells
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A person was vaccinated years ago and is now exposed to the pathogen. Which cells explain the rapid response?
- Memory B and T cells formed during the earlier vaccine response, which divide and act quickly
- Neutrophils that retained antibodies from the vaccine and release them when exposed again
- Killer T cells that are created only at the moment of exposure and so take several days
- Plasma cells that were stored in the thymus since the vaccination and are released into the blood
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Which statement best evaluates the use of vaccines based on memory cells?
- Vaccines work only by providing antibodies, so memory cells play no role in long-term protection at all
- Vaccines are effective because they generate memory cells, although protection may wane and some pathogens change their antigens
- Vaccines are completely ineffective, because memory cells are destroyed by the vaccine within a week of injection
- Vaccines are always permanent and need never be repeated, because memory cells never lose their ability to respond
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