Microbiologist's Exam - Only The Best Can Pass

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  • 1/36 Questions

    A bacterial infection that involves a protein-based antigen would result in IgG activation

    • True
    • False
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About This Quiz

Being a microbiologist, you are supposed to work for the biology of microorganisms at both a molecular and cellular level, as well as their ecology, including viruses, bacteria, algae, archaea, fungi etc.
But you have to be good at it right? This quiz is a tester for all microbiologists, take this exam and see if are you a good microbiologist.

Microbiologists Exam - Only The Best Can Pass - Quiz

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  • 2. 

    Myeloperoxidase pathways can occur without oxygen. 

    • True

    • False

    Correct Answer
    A. False
    Explanation
    The statement is false because myeloperoxidase pathways are dependent on the presence of oxygen. Myeloperoxidase is an enzyme found in certain white blood cells, and it requires oxygen to function properly. Without oxygen, the myeloperoxidase pathways cannot occur.

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  • 3. 

    Complement fixation refers to

    • the ingestion of C3b-coated bacteria by macrophages

    • The destruction of complement in serum by heating at 56°C for 30 minutes.

    • The binding of complement components by antigen-antibody complexes.

    • the interaction of C3b with mast cells

    Correct Answer
    A. The binding of complement components by antigen-antibody complexes.
    Explanation
    Complement fixation refers to the binding of complement components by antigen-antibody complexes. This process occurs when antibodies bind to antigens, forming immune complexes. These immune complexes then activate the complement system, leading to the binding of complement components to the immune complexes. This binding can result in various immune responses, including inflammation, opsonization, and lysis of the antigen-antibody complexes.

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  • 4. 

    A positive tuberculin skin test (a delayed hypersensitivity reaction) indicates that

    • A humoral immune response has occurred.

    • A cell-mediated immune response has occurred

    • Both the T and B cell systems are functional

    • Only the B cell system is functional

    Correct Answer
    A. A cell-mediated immune response has occurred
    Explanation
    A positive tuberculin skin test indicates that a cell-mediated immune response has occurred. This is because a tuberculin skin test measures the delayed hypersensitivity reaction, which is mediated by T cells. These T cells recognize and respond to antigens from the tuberculosis bacteria, leading to inflammation at the site of injection. This response is characteristic of a cell-mediated immune response, which involves the activation of T cells and other immune cells to eliminate the pathogen.

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  • 5. 

    Natural killer cells are

    • B cells that can kill without complement

    • Cytotoxic T cells

    • Increased by immunization

    • Able to kill virus-infected cells without prior sensitization.

    Correct Answer
    A. Able to kill virus-infected cells without prior sensitization.
    Explanation
    Natural killer cells are able to kill virus-infected cells without prior sensitization. Unlike cytotoxic T cells, which require prior exposure to specific antigens, natural killer cells can recognize and kill infected cells without the need for prior sensitization. This ability allows natural killer cells to provide a rapid response to viral infections and play a crucial role in the innate immune system.

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  • 6. 

    Your patient became ill 10 days ago with a viral disease. Laboratory examination reveals that the patient's antibodies against this virus have a high ratio of IgM to IgG. What is your conclusion?

    • It is unlikely that the patient has encountered this organism previously

    • The patient is predisposed to IgE-mediated hypersensitivity reactions

    • The information given is irrelevant to previous antigen exposure

    • It is likely that the patient has an autoimmune disease

    Correct Answer
    A. It is unlikely that the patient has encountered this organism previously
    Explanation
    The high ratio of IgM to IgG antibodies suggests that the patient's immune system is producing a primary immune response to the viral disease. This indicates that the patient has not encountered this organism previously, as a secondary immune response would be expected in that case.

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  • 7. 

    Which is the most effective antigen presenting cell?

    • Macrophage

    • Dendritic Cell

    • Kupffer cell

    • B-Cell

    Correct Answer
    A. Dendritic Cell
    Explanation
    Dendritic cells are the most effective antigen presenting cells. They have the ability to capture, process, and present antigens to T cells, initiating an immune response. Dendritic cells have specialized structures called dendrites that increase their surface area, allowing for efficient antigen uptake. They also express high levels of major histocompatibility complex (MHC) molecules, which are crucial for presenting antigens to T cells. Additionally, dendritic cells have the ability to migrate to lymphoid tissues, where they can interact with T cells and initiate an immune response.

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  • 8. 

    __________ are released by cells and affect other cell types locally without being transported in blood.

    • Autocrine Chemical Signals

    • Paracrine Chemical Signals

    • Hormones

    • Neurotransmitters

    Correct Answer
    A. Paracrine Chemical Signals
    Explanation
    Paracrine chemical signals are released by cells and affect other cell types locally without being transported in the blood. Unlike hormones, which are transported through the bloodstream to target cells in distant parts of the body, paracrine signals act on nearby cells within the same tissue or organ. Autocrine chemical signals act on the same cells that release them, while neurotransmitters are chemical signals that transmit signals across synapses in the nervous system. Therefore, the correct answer is paracrine chemical signals.

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  • 9. 

    Complement lyses cells by

    • Enzymatic digestion of the cell membrane

    • Activation of adenylate cyclase

    • Insertion of complement proteins into the cell membrane

    • Inhibition of elongation factor 2

    Correct Answer
    A. Insertion of complement proteins into the cell membrane
    Explanation
    Complement lyses cells by inserting complement proteins into the cell membrane. These complement proteins form a membrane attack complex (MAC) that creates pores in the cell membrane. These pores disrupt the integrity of the cell membrane, leading to the lysis or destruction of the cell. This mechanism is part of the immune response and helps to eliminate pathogens and infected cells from the body.

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  • 10. 

    The role of the macrophage during an antibody response is to

    • Make antibody

    • Lyse virus infected target cells

    • Activate Cytotoxic T cells

    • Process antigen and present it

    Correct Answer
    A. Process antigen and present it
    Explanation
    During an antibody response, macrophages play a crucial role in processing antigens and presenting them to other immune cells. Macrophages engulf and break down pathogens, such as viruses, into smaller fragments. These fragments are then displayed on the surface of the macrophage, allowing them to be recognized by other immune cells, such as T cells. This presentation of antigens by macrophages is essential for the activation of other immune cells and the initiation of an effective immune response against the pathogen.

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  • 11. 

    Which of these is not a pathway that complement can be activated?

    • Antibody secretes cytokines

    • Pathogen surface creates a local environment that allows complement to be activated

    • An antibody binds an antigen on pathogen surface

    • Lectin binds to pathogen surface

    Correct Answer
    A. Antibody secretes cytokines
    Explanation
    The complement system is a part of the immune system that helps in the elimination of pathogens. It can be activated through various pathways, including the binding of antibodies to antigens on the pathogen surface, the binding of lectins to the pathogen surface, and the creation of a local environment on the pathogen surface that allows complement activation. However, antibodies do not secrete cytokines. Cytokines are signaling molecules that help regulate immune responses, but they are not directly involved in complement activation. Therefore, "Antibody secretes cytokines" is not a pathway through which complement can be activated.

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  • 12. 

    Type question here

    • Answer option 1

    • Answer option 2

    • Answer option 3

    • Answer option 4

    Correct Answer
    A. Answer option 1
  • 13. 

    Antigen-presenting cells that activate helper T cells must express which one of the following on their surfaces?

    • IgE

    • Gamma Interferon

    • Class I MHC antigens

    • Class II MHC antigens

    Correct Answer
    A. Class II MHC antigens
    Explanation
    Antigen-presenting cells (APCs) play a crucial role in activating helper T cells. They do so by presenting antigens on their surfaces using major histocompatibility complex (MHC) molecules. Class II MHC antigens are specifically involved in presenting antigens to helper T cells. Therefore, APCs must express Class II MHC antigens on their surfaces to activate helper T cells. IgE and Gamma Interferon are not directly involved in antigen presentation, and Class I MHC antigens are involved in presenting antigens to cytotoxic T cells, not helper T cells.

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  • 14. 

    Which protein is necessary for signal transduction after an antigen binds with a T-Cell?

    • CD10

    • CD15

    • CD1

    • CD3

    Correct Answer
    A. CD3
    Explanation
    CD3 is the correct answer because it is a protein that is necessary for signal transduction after an antigen binds with a T-cell. CD3 is a complex of proteins that is associated with the T-cell receptor (TCR) on the surface of T-cells. When an antigen binds to the TCR, CD3 helps to transmit the signal into the T-cell, initiating a cascade of events that ultimately leads to T-cell activation and the immune response. CD10, CD15, and CD1 are not directly involved in signal transduction after antigen binding.

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  • 15. 

    C3a and C5a can cause

    • Bacterial lysis.

    • Vascular permeability.

    • Phagocytosis of IgE-coated bacteria.

    • Aggregation of C4 and C2.

    Correct Answer
    A. Vascular permeability.
    Explanation
    C3a and C5a are complement proteins that are released during complement activation. These proteins are known as anaphylatoxins and are responsible for inducing inflammation. One of the main effects of C3a and C5a is increasing vascular permeability, which allows for the recruitment of immune cells to the site of infection or injury. This increased permeability allows for the leakage of fluid and proteins from blood vessels into the surrounding tissues, leading to swelling and redness. So, the correct answer is vascular permeability.

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  • 16. 

    The main advantage of passive immunization over active immunization is that

    • It can be administered orally

    • It provides antibody more rapidly

    • Antibody persists for a longer period

    • It contains primarily IgM

    Correct Answer
    A. It provides antibody more rapidly
    Explanation
    Passive immunization involves the administration of pre-formed antibodies, which provides immediate protection against a specific pathogen. This is in contrast to active immunization, where the body needs time to produce its own antibodies. Therefore, passive immunization is advantageous as it offers a more rapid response to an infection or disease.

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  • 17. 

    Each of the following statements concerning class II MHC proteins is correct EXCEPT:

    • They are made of a long alpha chain and short beta chain

    • They have a high degree of polymorphism

    • They are involved in antigen presentation by macrophages

    • They have a binding site for CD4 proteins

    Correct Answer
    A. They are made of a long alpha chain and short beta chain
    Explanation
    MHC Class I has one long alpha and a short beta
    MHC Class II has an alpha chain and a beta chain of equal length

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  • 18. 

    Which of these is not related to immunogenicity?

    • Age of patient

    • Protein Structure

    • Size of molecule

    • Route of administration

    • All of the above are related to immunogenicity

    Correct Answer
    A. All of the above are related to immunogenicity
    Explanation
    All of the options mentioned in the question are related to immunogenicity. The age of the patient can affect the immune response, as the immune system may weaken with age. Protein structure plays a crucial role in determining the immunogenicity of a molecule, as certain structural features can trigger an immune response. The size of the molecule can also influence immunogenicity, as larger molecules may be more likely to be recognized by the immune system. Finally, the route of administration can impact the immune response, as different routes may result in varying levels of immune activation.

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  • 19. 

    Which of the following is correct concerning the structure of the T-Cell Receptor (TCR)

    • The constant region determines Antigen specificity

    • Only the alpha chain contains a variable region

    • Each T-cell bears a TCR of only one specificity

    • The T-cell receptor is not attached to the membrane of the T-Cell

    Correct Answer
    A. Each T-cell bears a TCR of only one specificity
    Explanation
    Each T-cell bears a TCR of only one specificity means that each T-cell has a T-cell receptor (TCR) that is specific to a particular antigen. This implies that T-cells are capable of recognizing and responding to a wide variety of antigens, as each T-cell carries a unique TCR that can bind to a specific antigen. This specificity is crucial for the immune response, as it allows T-cells to identify and target specific pathogens or abnormal cells in the body.

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  • 20. 

    Which of these is not a end-result (product) of oxygen-dependent myeloperoxidase-independent reactions?

    • Singlet Oxygen

    • Hydrogen Peroxide

    • Chlorous Acid

    • Hydroxyl Radical

    • Superoxide Anion

    Correct Answer
    A. Chlorous Acid
    Explanation
    Chlorous Acid is not a product of oxygen-dependent myeloperoxidase-independent reactions. The other options, Singlet Oxygen, Hydrogen Peroxide, Hydroxyl Radical, and Superoxide Anion, are all end-products of these reactions.

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  • 21. 

    Oxygen-independent killing utilizes all of the following EXCEPT..

    • Respiratory Burst mechanism

    • Lysozyme

    • Lactoferrin

    • Proteases

    Correct Answer
    A. Respiratory Burst mechanism
    Explanation
    Oxygen-independent killing refers to the mechanisms by which immune cells can kill pathogens without the need for oxygen. The respiratory burst mechanism is a process in which immune cells produce reactive oxygen species (ROS) to kill pathogens. Therefore, it is not excluded from oxygen-independent killing. On the other hand, lysozyme, lactoferrin, and proteases are all examples of oxygen-independent killing mechanisms. Lysozyme breaks down bacterial cell walls, lactoferrin binds to iron and prevents bacterial growth, and proteases degrade bacterial proteins.

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  • 22. 

    Name the intercellular chemical signal that is released by cells and has a local effect on the same cell type as that from which the chemical signal is released.

    • Paracrine Chemical Signal

    • Hormone

    • Autocrine Chemical Signal

    • Hormone

    • Neurotransmitter

    Correct Answer
    A. Autocrine Chemical Signal
    Explanation
    Autocrine chemical signals are released by cells and have a local effect on the same cell type that released them. This means that the chemical signal acts on the same cells that secreted it, influencing their own behavior or regulating their own functions. Unlike paracrine signals, which act on nearby cells of a different type, or hormones, which are released into the bloodstream to act on distant target cells, autocrine signals have a more localized effect within the same cell population. Neurotransmitters, on the other hand, are chemical signals that transmit signals between nerve cells in the nervous system.

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  • 23. 

    The principal difference between cytotoxic (type II) and immune complex (type III) hypersensitivity is

    • The class (isotype) of antibody.

    • The site where antigen-antibody complexes are formed.

    • The participation of complement.

    • The participation of T cells.

    Correct Answer
    A. The site where antigen-antibody complexes are formed.
    Explanation
    Type II Hypersensitivities - Antibody binds to antigens on self cells and complement is activated
    Type III Hypersensitivities - Antibodies bind free antigens and move to tissues and then complement is activated

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  • 24. 

    What is one product that oyxgen-dependent myeloperoxidase-dependent and myeloperoxidase-independent reactions share?

    • Superoxide Anion

    • Water

    • Hydrogen Peroxide

    • Hypochlorous Acid

    • Ozone

    Correct Answer
    A. Superoxide Anion
    Explanation
    Oxygen-dependent myeloperoxidase-dependent and myeloperoxidase-independent reactions both involve the production of reactive oxygen species (ROS) as part of the immune response. Superoxide anion is a type of ROS that is generated in both types of reactions. It is produced by various enzymes and plays a role in oxidative stress and inflammation. Therefore, superoxide anion is the shared product in both types of reactions.

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  • 25. 

    Which of these is an example of a PRR (pattern recognition receptor) of the innate immune system?

    • LPS

    • Flagellin

    • MHC

    • TLR (Toll-like Receptors)

    Correct Answer
    A. TLR (Toll-like Receptors)
    Explanation
    TLR (Toll-like Receptors) is an example of a PRR (pattern recognition receptor) of the innate immune system. PRRs are proteins that recognize specific patterns on pathogens and trigger an immune response. TLRs are a group of PRRs that are located on the surface of immune cells and recognize various pathogen-associated molecular patterns (PAMPs). They play a crucial role in initiating the innate immune response by recognizing and binding to these PAMPs, leading to the activation of downstream signaling pathways and the production of inflammatory cytokines.

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  • 26. 

    Which of these is an example of a T-dependent antigen?

    • Protein

    • Water

    • Polysaccharide

    • Cholesterol

    Correct Answer
    A. Protein
    Explanation
    A T-dependent antigen refers to an antigen that requires the assistance of T cells to initiate an immune response. Proteins are known to be T-dependent antigens because they can activate T cells and stimulate the production of specific antibodies. Water, polysaccharides, and cholesterol are not typically classified as T-dependent antigens as they do not elicit a strong T cell response.

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  • 27. 

    Which of these is an end-result (product) of oxygen-dependent myeloperoxidase-dependent reactions?

    • Hydroxyl Radical

    • Hydrochloric Acid

    • Hydrogen Peroxide

    • Hypochlorous Acid

    • Superoxide Dismutase

    Correct Answer
    A. Hypochlorous Acid
    Explanation
    Hypochlorous acid is an end-result of oxygen-dependent myeloperoxidase-dependent reactions. Myeloperoxidase is an enzyme found in white blood cells that catalyzes the reaction between hydrogen peroxide and chloride ions, resulting in the formation of hypochlorous acid. Hypochlorous acid is a potent oxidant and antimicrobial agent that plays a crucial role in the immune response, particularly in killing bacteria and other pathogens.

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  • 28. 

    Detoxification can break down superoxide anions produced by respiratory burst mechanisms. Which of these is a product of this reaction?

    • Ozone

    • Hydrogen Peroxide

    • Hypochlorous Acid

    • Singlet Oxygen

    • NADPH

    Correct Answer
    A. Hydrogen Peroxide
    Explanation
    Detoxification processes can break down superoxide anions generated by respiratory burst mechanisms. One of the products of this reaction is hydrogen peroxide.

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  • 29. 

    Immunoglobulin classes are determined by the constant region of the heavy chain and the subclasses are determined by the constant region of the light chain

    • True

    • False

    Correct Answer
    A. False
    Explanation
    The explanation for the answer "False" is that immunoglobulin classes are actually determined by the constant region of the heavy chain, but the subclasses are determined by the variable region of the heavy chain. The constant region of the light chain does not play a role in determining the immunoglobulin classes or subclasses.

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  • 30. 

    After binding to its specific antigen, a B lymphocyte may switch its

    • Immunoglobulin light-chain isotype.

    • Immunoglobulin heavy-chain class.

    • Variable region of the immunoglobulin heavy chain.

    • Constant region of the immunoglobulin light chain.

    Correct Answer
    A. Immunoglobulin heavy-chain class.
    Explanation
    A B lymphocyte can switch its immunoglobulin heavy-chain class after binding to its specific antigen. This is known as class switching and it allows the B lymphocyte to produce antibodies of different isotypes, such as IgM, IgG, IgA, etc. Class switching is an important mechanism in the immune response as it allows for the production of antibodies with different effector functions to combat different types of pathogens.

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  • 31. 

    Hereditary angioedema is a disorder that results in rapidly swelling of the tissue. This disorder involves overproduction of what complement protein

    • C2b

    • C3a

    • C5a

    • C3b

    Correct Answer
    A. C2b
    Explanation
    Hereditary angioedema is a disorder characterized by rapid swelling of the tissue. This condition is caused by an overproduction of a complement protein called C2b. Complement proteins are part of the immune system and play a role in inflammation and immune response. In the case of hereditary angioedema, the excessive production of C2b leads to the swelling of tissues, particularly in the face, hands, feet, and airways.

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  • 32. 

    Which one of the following properties of antibodies is NOT dependent on the structure of the heavy-chain constant region?

    • Ability to cross the placenta

    • Isotype (class)

    • Ability to fix complement

    • Affinity for antigen

    Correct Answer
    A. Affinity for antigen
    Explanation
    The affinity for antigen refers to the strength of the binding between an antibody and its target antigen. This property is determined by the variable region of the antibody, specifically the antigen-binding site. The heavy-chain constant region, on the other hand, is responsible for other functions such as isotype (class) determination, ability to fix complement, and ability to cross the placenta. Therefore, the affinity for antigen is not dependent on the structure of the heavy-chain constant region.

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  • 33. 

    Which of these are intracellular killing pathways?

    • Nitric Oxide Dependent Killing

    • Oxygen Dependent Myeloperoxidase-Independent Killing

    • Oxygen Independent Killing

    • Oxygen Dependent Myeloperoxidase-Dependent Killing

    • All of the above

    • B, C, and D

    Correct Answer
    A. B, C, and D
    Explanation
    The intracellular killing pathways mentioned in the options are Nitric Oxide Dependent Killing, Oxygen Dependent Myeloperoxidase-Independent Killing, Oxygen Independent Killing, and Oxygen Dependent Myeloperoxidase-Dependent Killing. The correct answer states that all of these pathways are intracellular killing pathways, indicating that options B, C, and D are correct.

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  • 34. 

    An IgG molecule may be composed of two identical heavy chains and a kappa and lambda light chain with identical variable regions

    • True

    • False

    Correct Answer
    A. False
    Explanation
    All IgG molecules are composed of two identical heavy and two identical light chains, since the B cell that makes the immunoglobulin only expresses one heavy and one light chain. Thus, an IgG could not have both a kappa and a lambda chain

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  • 35. 

    After exposure to antigen the heavy and light chain genes rearrange to generate the receptor for antigen

    • True

    • False

    Correct Answer
    A. False
    Explanation
    The genes rearrange before exposure to the antigen

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  • 36. 

    Each of the following statements concerning class I MHC proteins is correct EXCEPT:

    • They are cell surface proteins on virtually all cells

    • They are recognition elements for cytotoxic T cells

    • They are codominantly expressed

    • They can utilize recombination to generate diversity

    Correct Answer
    A. They can utilize recombination to generate diversity
    Explanation
    Class I MHC proteins are cell surface proteins that are present on virtually all cells. They play a crucial role in the immune response by presenting antigens to cytotoxic T cells, which then destroy the infected cells. Class I MHC proteins are codominantly expressed, meaning that both copies of the gene are expressed equally. However, they do not utilize recombination to generate diversity. Instead, diversity in class I MHC proteins is generated through a process called antigen processing and presentation, where a wide range of antigens can be presented on the cell surface.

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  • Mar 20, 2023
    Quiz Edited by
    ProProfs Editorial Team
  • Sep 07, 2013
    Quiz Created by
    Uncadf
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