MDCAT WITH UMAR SANI
Daily Practice Test
CHAPTER:IMMUNITY
1. Which cells are primarily responsible for producing antibodies? (2016)
a) Macrophages
b) T cells
c) B cells
d) Neutrophils
2. What is the main function of helper T cells in the immune response? (2017)
a) Phagocytosis
b) Antibody production
c) Activating other immune cells
d) Destroying infected cells
3. Which of the following is a component of the innate immune system? (2018)
a) Antibodies
b) Cytotoxic T cells
c) Skin
d) Memory B cells
4. What is the role of the thymus in the immune system? (2019)
a) Producing red blood cells
b) Maturation of T cells
c) Filtering lymph
d) Producing antibodies
5. Which type of immunity is provided by a vaccine? (2020)
a) Natural active immunity
b) Artificial active immunity
c) Natural passive immunity
d) Artificial passive immunity
6. Which immunoglobulin is most abundant in the bloodstream? (2021)
a) IgA
b) IgM
c) IgG
d) IgE
7. What is the function of cytotoxic T cells? (2016)
a) Produce antibodies
b) Help other immune cells
c) Kill infected cells
d) Activate B cells
8. Which of the following is an autoimmune disease? (2017)
a) Tuberculosis
b) Rheumatoid arthritis
c) Malaria
d) Measles
9. What type of cells are memory cells derived from? (2018)
a) T cells only
b) B cells only
c) Both T cells and B cells
d) Macrophages
10. Which pathway involves the complement system in immune responses? (2019)
a) Classical pathway
b) Alternative pathway
c) Lectin pathway
d) All of the above
11. What triggers the inflammatory response in the immune system? (2020)
a) Antibodies
b) Histamines
c) T cells
d) Cytokines
12. Which organ is the primary site for the production of immune cells? (2021)
a) Thymus
b) Bone marrow
c) Spleen
d) Lymph nodes
13. Which part of the immune system is responsible for recognizing antigens? (2016)
a) Phagocytes
b) Antibodies
c) T cell receptors
d) Complement proteins
14. What is the primary role of natural killer (NK) cells? (2017)
a) Phagocytosis
b) Antigen presentation
c) Destroying virus-infected cells
d) Producing antibodies
15. Which cells act as antigen-presenting cells (APCs)? (2018)
a) T cells
b) B cells
c) Dendritic cells
d) Neutrophils
16. What is the role of interferons in the immune system? (2019)
a) Stimulate B cell activation
b) Inhibit viral replication
c) Enhance phagocytosis
d) Destroy infected cells
17. Which immune response is characterized by the production of antibodies? (2020)
a) Cell-mediated immunity
b) Humoral immunity
c) Innate immunity
d) Passive immunity
18. Which cells are involved in the cell-mediated immune response? (2021)
a) B cells
b) Plasma cells
c) T cells
d) Macrophages
19. Which molecule acts as a signal for the immune system to respond? (2016)
a) Antigen
b) Histamine
c) Cytokine
d) Antibody
20. What is the function of regulatory T cells in the immune system? (2017)
a) Suppress immune responses
b) Activate B cells
c) Produce antibodies
d) Destroy pathogens
21. Which immunoglobulin is associated with allergic reactions? (2018)
a) IgA
b) IgM
c) IgG
d) IgE
22. Which cells are the first responders to a site of infection? (2019)
a) Neutrophils
b) Macrophages
c) B cells
d) T cells
23. Which type of hypersensitivity involves antibodies and is immediate? (2020)
a) Type I
b) Type II
c) Type III
d) Type IV
24. Which part of the immune system is primarily responsible for fighting bacterial
infections? (2021)
a) T cells
b) B cells
c) Macrophages
d) Natural killer cells
25. What is the purpose of the major histocompatibility complex (MHC) in immunity?
(2016)
a) Produce antibodies
b) Present antigens
c) Destroy pathogens
d) Activate T cells
26. Which organ stores and filters blood as part of the immune system? (2017)
a) Thymus
b) Spleen
c) Liver
d) Lymph nodes
27. What is the role of plasma cells in the immune system? (2018)
a) Produce cytokines
b) Present antigens
c) Produce antibodies
d) Attack infected cells
28. Which type of immunity involves the transfer of antibodies from mother to child?
(2019)
a) Natural active immunity
b) Artificial active immunity
c) Natural passive immunity
d) Artificial passive immunity
29. Which cells are primarily involved in the allergic response? (2020)
a) T cells
b) B cells
c) Mast cells
d) Neutrophils
30. Which enzyme is present in tears and saliva that helps destroy bacteria? (2021)
a) Amylase
b) Lysozyme
c) Protease
d) Lipase
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ANSWERS WITH EXPLANATION
1. c) B cells
Explanation: B cells are a type of white blood cell that, when activated, differentiate
into plasma cells that produce antibodies specific to antigens.
2. c) Activating other immune cells
Explanation: Helper T cells (CD4+ T cells) play a critical role in the immune response
by secreting cytokines that activate and coordinate the activity of other immune cells
like B cells and cytotoxic T cells.
3. c) Skin
Explanation: The skin acts as a physical barrier and is a component of the innate
immune system, providing the first line of defense against pathogens.
4. b) Maturation of T cells
Explanation: The thymus is where T cells mature. Immature T cells (thymocytes)
develop into functional T cells capable of recognizing specific antigens.
5. b) Artificial active immunity
Explanation: Vaccines stimulate the immune system to produce antibodies and
memory cells against specific pathogens, providing long-term immunity without
causing the disease.
6. c) IgG
Explanation: IgG is the most abundant immunoglobulin in the blood and provides the
majority of antibody-based immunity against pathogens.
7. c) Kill infected cells
Explanation: Cytotoxic T cells (CD8+ T cells) recognize and destroy cells infected with
viruses or other intracellular pathogens by inducing apoptosis (programmed cell
death).
8. b) Rheumatoid arthritis
Explanation: Rheumatoid arthritis is an autoimmune disease in which the immune
system mistakenly attacks the body's own tissues, particularly the joints.
9. c) Both T cells and B cells
Explanation: Memory cells, which can be either memory T cells or memory B cells, are
long-lived and can quickly respond to previously encountered antigens, providing
faster and stronger immune responses.
10. d) All of the above
Explanation: The complement system can be activated through the classical,
alternative, and lectin pathways, each leading to the activation of a cascade of
proteins that enhance immune responses.
11. b) Histamines
Explanation: Histamines are released by mast cells and basophils during an immune
response, causing vasodilation and increased permeability of blood vessels, leading
to inflammation.
12. b) Bone marrow
Explanation: Bone marrow is the primary site of hematopoiesis, where all blood cells,
including immune cells such as lymphocytes, are produced from hematopoietic stem
cells.
13. c) T cell receptors
Explanation: T cell receptors (TCRs) on T cells recognize and bind to specific antigens
presented by antigen-presenting cells, initiating an immune response.
14. c) Destroying virus-infected cells
Explanatio: Natural killer (NK) cells are a type of lymphocyte that can recognize and
destroy virus-infected cells or tumor cells without prior sensitization.
15. c) Dendritic cells
Explanation: Dendritic cells are professional antigen-presenting cells that process
antigens and present them to T cells, thus initiating the adaptive immune response.
16. b) Inhibit viral replication
Explanation: Interferons are cytokines produced by virus-infected cells that help
protect nearby cells by inhibiting viral replication and enhancing the immune
response.
17. b) Humoral immunity
Explanation: Humoral immunity involves B cells and the production of antibodies that
circulate in the blood and lymph, targeting extracellular pathogens and toxins.
18. c) T cells
Explanation: Cell-mediated immunity primarily involves T cells, which directly attack
infected or cancerous cells and coordinate the overall immune response.
19. c) Cytokine
Explanation: Cytokines are signaling molecules released by immune cells that
regulate the intensity and duration of the immune response by communicating
between cells.
20. a) Suppress immune responses
Explanation: Regulatory T cells (Tregs) help maintain immune system balance by
suppressing excessive immune responses and preventing autoimmune diseases.
21. d) IgE
Explanation: IgE antibodies are involved in allergic reactions and bind to allergens,
triggering the release of histamine and other chemicals from mast cells.
22. a) Neutrophils
Explanation: Neutrophils are a type of white blood cell that quickly migrate to
infection sites, where they engulf and destroy bacteria and other pathogens.
23. a) Type I
Explanation: Type I hypersensitivity, or immediate hypersensitivity, is mediated by IgE
antibodies and results in allergic reactions such as hay fever or anaphylaxis.
24. b) B cells
Explanation: B cells produce antibodies that specifically target and neutralize
bacteria, making them essential for fighting bacterial infections.
25. b) Present antigens
Explanation: MHC molecules on the surface of cells present antigens to T cells,
facilitating the recognition of foreign substances by the immune system.
26. b) Spleen
Explanation: The spleen filters blood, removing old or damaged red blood cells and
pathogens. It also plays a role in the immune response by producing lymphocytes.
27. c) Produce antibodies
Explanation: Plasma cells are differentiated B cells that produce and secrete large
quantities of antibodies specific to an antigen.
28. c) Natural passive immunity
Explanation: Natural passive immunity occurs when a mother transfers antibodies to
her child through the placenta or breast milk, providing temporary protection.
29. c) Mast cells
Explanation: Mast cells release histamine and other mediators during an allergic
response, causing symptoms such as itching, swelling, and redness.
30. b) Lysozyme
Explanation: Lysozyme is an enzyme found in tears, saliva, and other body fluids that
breaks down bacterial cell walls, providing a protective antimicrobial function.
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