Biology
Human Immunity and Blood
2,051 Questions
Human immunity and blood questions cover the physiological mechanisms protecting the body against diseases and the components of blood. Topics include blood groups, cell mediated immunity, monoclonal antibodies, and blood coagulation. These biology topics frequently appear in general science sections of competitive exams.
Blood groupsCell mediated immunityMonoclonal antibodiesBlood coagulationCancer immunology
Human Immunity and Blood Questions
Which type of immune cell is primarily responsible for phagocytosing and destroying tumor cells?
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Natural killer cells
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Cytotoxic T cells
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Helper T cells
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Macrophages
D
Correct answer
Explanation
Macrophages are phagocytic cells that play a role in tumor immunity by engulfing and destroying tumor cells, as well as presenting tumor antigens to other immune cells.
What is the term for the process by which tumor cells can suppress or downregulate the immune response against them?
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Immune surveillance
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Immune tolerance
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Immune evasion
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Immune exhaustion
C
Correct answer
Explanation
Immune evasion refers to the strategies employed by tumor cells to suppress or downregulate the immune response against them, such as expressing inhibitory molecules or releasing immunosuppressive factors.
Which type of immune cell is known for its ability to produce antibodies that target tumor-associated antigens?
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Natural killer cells
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Cytotoxic T cells
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Helper T cells
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B cells
D
Correct answer
Explanation
B cells are responsible for producing antibodies, which can recognize and bind to tumor-associated antigens, leading to the activation of complement and antibody-dependent cell-mediated cytotoxicity (ADCC).
What is the term for the process by which the immune system distinguishes between self and non-self molecules?
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Immune surveillance
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Immune tolerance
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Immune evasion
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Immune exhaustion
B
Correct answer
Explanation
Immune tolerance refers to the ability of the immune system to distinguish between self and non-self molecules, preventing autoimmune reactions against self-antigens.
Which type of immune response is mediated by antibodies?
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Humoral
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Cell-mediated
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Innate
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Passive
A
Correct answer
Explanation
The humoral immune response is mediated by antibodies, which are produced by B cells and plasma cells.
Which type of immune response is mediated by T cells?
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Humoral
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Cell-mediated
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Innate
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Passive
B
Correct answer
Explanation
The cell-mediated immune response is mediated by T cells, which directly attack and kill infected cells.
What is the difference between humoral and cell-mediated immunity?
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Humoral immunity is mediated by antibodies, while cell-mediated immunity is mediated by T cells.
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Humoral immunity is mediated by T cells, while cell-mediated immunity is mediated by antibodies.
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Humoral immunity is acquired through vaccination or infection, while cell-mediated immunity is acquired through the transfer of antibodies or T cells from another individual.
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Humoral immunity is long-lasting, while cell-mediated immunity is short-lived.
A
Correct answer
Explanation
Humoral immunity is mediated by antibodies, while cell-mediated immunity is mediated by T cells.
What is the role of cytokines in adaptive immunity?
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To activate complement
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To kill infected cells
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To regulate the immune response
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To produce antibodies
C
Correct answer
Explanation
Cytokines regulate the immune response by controlling the activation, differentiation, and proliferation of immune cells.
What are the two main types of T cell receptors?
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Alpha-beta (αβ) and gamma-delta (γδ)
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Immunoglobulin (Ig) and T cell receptor (TCR)
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Major histocompatibility complex (MHC) class I and class II
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Interleukin (IL) and interferon (IFN)
A
Correct answer
Explanation
There are two main types of T cell receptors: alpha-beta (αβ) and gamma-delta (γδ). αβ T cells are the most common type and are involved in adaptive immune responses, while γδ T cells are less common and are involved in innate immune responses.
Which type of MHC molecule is recognized by αβ T cell receptors?
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MHC class I
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MHC class II
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Both MHC class I and class II
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Neither MHC class I nor class II
C
Correct answer
Explanation
αβ T cell receptors can recognize antigens presented on both MHC class I and class II molecules. MHC class I molecules present antigens derived from intracellular pathogens, while MHC class II molecules present antigens derived from extracellular pathogens.
Which type of MHC molecule is recognized by γδ T cell receptors?
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MHC class I
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MHC class II
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Both MHC class I and class II
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Neither MHC class I nor class II
D
Correct answer
Explanation
γδ T cell receptors do not recognize antigens presented on MHC molecules. Instead, they recognize non-peptide antigens, such as lipids and phosphoantigens, that are presented by other molecules on the surface of cells.
What is the role of CD4 and CD8 co-receptors in T cell activation?
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They bind to MHC molecules and help stabilize the interaction between the TCR and MHC-antigen complex.
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They bind to antigens and help deliver them to the TCR.
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They bind to other T cells and help form an immunological synapse.
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They bind to cytokines and help regulate T cell responses.
A
Correct answer
Explanation
CD4 and CD8 co-receptors bind to MHC molecules on the surface of antigen-presenting cells and help stabilize the interaction between the TCR and the MHC-antigen complex. This interaction is essential for the activation of T cells.
What is the role of the Lck tyrosine kinase in T cell activation?
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It phosphorylates the ζ-chain and other signaling molecules, leading to T cell activation.
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It binds to the TCR and helps stabilize the TCR-MHC-antigen interaction.
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It helps recruit other signaling molecules to the TCR complex.
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None of the above
A
Correct answer
Explanation
The Lck tyrosine kinase is a signaling molecule that is associated with the TCR complex. It phosphorylates the ζ-chain and other signaling molecules, leading to T cell activation.
What is the role of the PLCγ1 enzyme in T cell activation?
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It hydrolyzes PIP2 to generate IP3 and DAG, leading to increased intracellular calcium levels and activation of PKC.
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It binds to the TCR and helps stabilize the TCR-MHC-antigen interaction.
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It helps recruit other signaling molecules to the TCR complex.
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None of the above
A
Correct answer
Explanation
The PLCγ1 enzyme is a signaling molecule that is associated with the TCR complex. It hydrolyzes PIP2 to generate IP3 and DAG, leading to increased intracellular calcium levels and activation of PKC.
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Substances that trigger an immune response
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Antibodies produced by the immune system
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Cells that recognize and attack antigens
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Proteins found in the blood
A
Correct answer
Explanation
Antigens are substances that are recognized by the immune system as foreign and potentially harmful. They can be proteins, carbohydrates, lipids, or nucleic acids.