Immunity

Immunity MDCAT MCQs with answers

46 past paper MCQs from Biology unit 12, Immunity, across 1 topic. They are arranged topic by topic; bigger topics show a sample here and link to their full set and to study notes. Tap “Show answer” for the correct option and a short solution.

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Specific Defence Mechanism

1.______ proteins are produced by white blood cells in response to ______ and provide immunity. (MDCAT 2022)

  1. antibiotics, antigens
  2. antibodies, red blood cells
  3. globulins, histamine
  4. antibodies, antigens
Show answer

Correct answer: (d) antibodies, antigens

Lymphocytes make antibodies against a specific antigen, which is what specific immunity rests on.

2.Which statement best explains the difference between humoral and cell mediated Immune response? (UHS MDCAT 2025)

  1. Humoral immunity involves B-Lymphocytes and cell mediated immunity involves T-Lymphocytes
  2. Humoral immunity destroys viruses and cell mediated immunity destroys bacteria
  3. Humoral immunity is specific and cell mediated immunity is nonspecific
  4. Humoral immunity uses antibodies and cell mediated immunity does not involve immune cells
Show answer

Correct answer: (a) Humoral immunity involves B-Lymphocytes and cell mediated immunity involves T-Lymphocytes

Humoral immunity is the work of the B lymphocytes and their antibodies; cell mediated immunity is the work of the T lymphocytes.

3.The primary role of helper T cells in immune response is: (KMU MDCAT 2025)

  1. Secreting perforins to destroy target cells
  2. Assisting B-cells and other T-cells in their function
  3. Inhibiting over activity of the immune system
  4. Engulfing and digesting pathogens
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Correct answer: (b) Assisting B-cells and other T-cells in their function

Helper T cells recognize the antigen and then switch on the B cells and the killer T cells.

4.Identify the primary component of innate immune defense. (KMU MDCAT 2025)

  1. Complement system and interferons
  2. Physical component of skin defense
  3. Specific recognition and memory of pathogens
  4. General inflammation and the site of infection
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Correct answer: (b) Physical component of skin defense

Innate defence is non-specific, and the skin is its first physical barrier.

5.A woman cuts her finger while working in kitchen. Which chemical substance will cause inflammation around wound? (NUMS MDCAT 2025)

  1. Interleukin – I
  2. Histamine
  3. Interleukin – II
  4. Heparin
Show answer

Correct answer: (b) Histamine

Damaged mast cells release histamine, which widens the vessels and brings the redness and swelling.

6.When antibodies produced by B-cells, kill the antigens then it is called: (SIBA MDCAT 2025)

  1. Cell mediated response
  2. Passive response
  3. Humoral response
  4. Cells collaborated response
Show answer

Correct answer: (c) Humoral response

Immunity carried by antibodies in the body fluids is the humoral response.

7.B-Lymphocytes are formed and matured in: (SIBA MDCAT 2025)

  1. Liver
  2. Spleen
  3. Bone marrow
  4. Thymus
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Correct answer: (c) Bone marrow

B lymphocytes are made in the bone marrow and mature there; T cells finish in the thymus.

8.A person has swollen lymph nodes after throat infection. What does this indicate? (SIBA MDCAT 2025)

  1. Failure of circulatory system
  2. Extra glucose storage
  3. Active immune response
  4. Blockage of digestive track
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Correct answer: (c) Active immune response

Lymphocytes multiply in the node draining an infection, and the node swells.

9.Which cell type is essential for stimulating cell division of both B-cells and T-cells? (SZABMU MDCAT 2025)

  1. Plasma cells
  2. Memory cells
  3. Helper T-cells
  4. Neutrophils
Show answer

Correct answer: (c) Helper T-cells

Helper T cells release the interleukins that set both B and T cells dividing.

10.After Liver transplant, doctors suppress the T-lymphocyte activity in patient. Why? (SZABMU MDCAT 2025)

  1. To increase the rate of antibody production
  2. To prevent infections
  3. To avoid graft rejection immune system
  4. To produce memory cells faster
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Correct answer: (c) To avoid graft rejection immune system

T cells would attack the graft as foreign, so their activity is damped down.

11.In an inflammatory response, bradykinin causes? (KMU MDCAT 2024)

  1. Activation of natural killer cells
  2. Blockage in blood vessels
  3. Constriction of blood vessels
  4. Leakage of fluid from blood vessels
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Correct answer: (d) Leakage of fluid from blood vessels

Bradykinin makes the capillaries leaky, so fluid escapes into the tissue and it swells.

12.Which of the following is an example of passive immunity? (KMU MDCAT 2024)

  1. Antibodies from mother's milk
  2. Previous chickenpox infection
  3. Inactivated polio vaccine
  4. Live polio vaccine
Show answer

Correct answer: (a) Antibodies from mother's milk

Antibodies received ready made, as in breast milk, give passive immunity.

13.What directly triggers the activation of natural killer cells? (KMU MDCAT 2024)

  1. Free radicals
  2. Hydrogen peroxide
  3. Interferons
  4. Oxygen
Show answer

Correct answer: (c) Interferons

Interferons released by infected cells rouse the natural killer cells.

14.During Covid-19 epidemic, plasma of recovered patients was injected in covid patients. Which component of plasma was responsible for this? (NUMS MDCAT 2024)

  1. Plasminogen
  2. Interferons
  3. Antibodies
  4. Interleukin-I
Show answer

Correct answer: (c) Antibodies

The plasma of a recovered patient carries ready made antibodies against the virus.

15.Choose the one which is an example of artificial active immunity: (NUMS MDCAT 2024)

  1. Fetus receiving antibodies of mother through placenta
  2. Mother receiving antibodies
  3. Baby receiving MMR shots
  4. Prevention of disease due to previous infection
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Correct answer: (c) Baby receiving MMR shots

A vaccine makes the body raise its own antibodies, so the immunity is active and artificially induced.

16.Which of the following type of T cells are required for the activation of B cells? (NUMS MDCAT 2024)

  1. Helper T cells
  2. Cytotoxic T cells
  3. Suppressor T cells
  4. Memory T cells
Show answer

Correct answer: (a) Helper T cells

A helper T cell must recognize the antigen before the B cell will divide and make antibody.

17.---------- proteins are produced by WBCs in response to -------- and provide immunity? (UHS MDCAT 2023)

  1. Antibiotics, antigen
  2. Antibodies, RBC
  3. Globulin, histamine
  4. Antibodies, antigen
Show answer

Correct answer: (d) Antibodies, antigen

Lymphocytes make antibodies against a specific antigen.

18.Vaccination is an example of: (SZABMU MDCAT 2023)

  1. Natural passive immunity
  2. Natural active immunity
  3. Acquired/Artificial active immunity
  4. Acquired/Artificial passive immunity
Show answer

Correct answer: (c) Acquired/Artificial active immunity

A vaccine makes the body raise its own antibodies, so the immunity is active and artificially given.

19.Which of the following helps in developing immunity against germs? (SZABMU MDCAT 2023)

  1. Radiotherapy
  2. Chemotherapy
  3. Vaccines
  4. Antibiotics
Show answer

Correct answer: (c) Vaccines

A vaccine primes the body to make its own antibodies before the germ arrives.

20.Which may NOT be a mode of action of an antibody? (NUMS MDCAT 2023)

  1. Neutralizing an antigen
  2. Precipitating an antigen
  3. Secretion of cytokines
  4. Enhancing phagocytosis
Show answer

Correct answer: (c) Secretion of cytokines

Antibodies neutralize, precipitate and mark antigens for phagocytes; cytokines come from the cells themselves.

21.The cells which play very important role in developing immunity are: (NUMS MDCAT 2023)

  1. Monocytes
  2. Neutrophils
  3. Lymphocytes
  4. Thrombocytes
Show answer

Correct answer: (c) Lymphocytes

The lymphocytes, B cells and T cells, carry the specific immune response.

22.The molecules used to control virus during infection of animal cells are: (UHS MDCAT 2023)

  1. Interferon
  2. Histone
  3. Antigen
  4. Serum
Show answer

Correct answer: (a) Interferon

An infected cell releases interferon, which warns its neighbours to resist the virus.

23.Human immunodeficiency virus attack which of the following cells for its multiplication? (PMC MDCAT 2022)

  1. Neutrophils
  2. Macrophages
  3. Cytotoxic T cells
  4. Helper T cells
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Correct answer: (d) Helper T cells

HIV enters the helper T cell through its CD4 receptor and destroys it.

24.Which of the following provides long lasting protection against any infection? (PMC MDCAT 2022)

  1. Active immunity
  2. Passive immunity
  3. Skin
  4. Phagocytes
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Correct answer: (a) Active immunity

Active immunity leaves memory cells, so the protection lasts for years.

25.The method which helps in developing immunity against bacteria is: (NUMS MDCAT 2022)

  1. Radiotherapy
  2. Chemotherapy
  3. Vaccination
  4. Antibiotics
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Correct answer: (c) Vaccination

A vaccine primes the body to make its own antibodies.

26.Which is not a mode of action of an antibody? (NUMS MDCAT 2022)

  1. Precipitating an antigen
  2. Neutralizing an antigen
  3. Secreting cytokines
  4. Enhancing phagocytosis
Show answer

Correct answer: (c) Secreting cytokines

Antibodies neutralize, precipitate and mark antigens for phagocytes; cytokines come from the cells themselves.

27.Thymus is found in the human body in _____. (PMC Practice 2021)

  1. The medulla oblongata
  2. The mediastinum of the upper thorax
  3. Both Options A and B are correct
  4. None of these options is correct
Show answer

Correct answer: (b) The mediastinum of the upper thorax

The thymus lies in the mediastinum behind the sternum.

28.The cells which play a very important role in developing immunity are: (PMC MDCAT 2020)

  1. Monocytes
  2. Neutrophils
  3. Lymphocytes
  4. Thrombocytes
Show answer

Correct answer: (c) Lymphocytes

The lymphocytes, B cells and T cells, carry the specific immune response.

29.Antibodies are manufactured in: (PMC MDCAT 2020)

  1. T Lymphocytes
  2. Red Blood Cells
  3. Platelets
  4. B Lymphocytes
Show answer

Correct answer: (d) B Lymphocytes

B lymphocytes turn into plasma cells and those make the antibody.

30.Autoimmune diseases act as the principle of: (PMC MDCAT 2020)

  1. Self against antigens
  2. Antigen against self
  3. Self against self
  4. Antigen self destroyed
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Correct answer: (c) Self against self

In an autoimmune disease the immune system fails to tell self from foreign and attacks the body.

31.Now-a-days every newborn gets regular shots of vaccine for polio. It contains _________ for polio to make a child immune against this disease. (UHS MDCAT 2019)

  1. Antibiotics
  2. Antibodies
  3. Antigens
  4. Antisera
Show answer

Correct answer: (c) Antigens

A vaccine carries the antigen, and the body makes its own antibodies against it.

32.A person got an infection, he became ill but then he survived. What do you think which of immunity he would have developed? (UHS MDCAT 2019)

  1. Active immunity
  2. Artificially induced active immunity
  3. Passive immunity
  4. Naturally induced active immunity
Show answer

Correct answer: (d) Naturally induced active immunity

He made his own antibodies in answer to a natural infection, so the immunity is naturally acquired and active.

33.Cell-mediated immune response is given by: (UHS MDCAT 2018)

  1. T-lymphocytes
  2. B lymphocytes
  3. Neutrophils
  4. Macrophages
Show answer

Correct answer: (a) T-lymphocytes

Cell mediated immunity is carried by the T lymphocytes.

34.In immunoglobulins / antibodies, Two light chains and two heavy chains are linked to each other by: (UHS MDCAT 2018)

  1. Covalent bonds
  2. Hydrogen bonds
  3. Ionic bonds
  4. Disulphide bonds
Show answer

Correct answer: (d) Disulphide bonds

The four chains of an antibody are held together by disulphide bridges.

35.Antivenom given after a snake bite venom is an example of: (UHS MDCAT 2018)

  1. Natural passive immunity
  2. Artificial active immunity
  3. Natural active immunity
  4. Artificial passive immunity
Show answer

Correct answer: (d) Artificial passive immunity

Antibodies received ready made give passive immunity, and here they are given artificially.

36.The induction of immunity by artificially introducing antigens refers to: (UHS MDCAT 2017)

  1. Passive immunity
  2. Active immunity
  3. Artificial active immunity
  4. Passive active immunity
Show answer

Correct answer: (c) Artificial active immunity

A vaccine makes the body raise its own antibodies, so the immunity is active and artificially given.

37.In case of snake bite venom, passive immunity is produced by antitoxins, so the serum is called as: (UHS MDCAT 2017)

  1. Antivenom serum
  2. Antiserum
  3. Passive immunity serum
  4. Anti snake serum
Show answer

Correct answer: (a) Antivenom serum

Antivenom serum carries ready made antibodies against the venom.

38.An antibody molecule has total number of how many polypeptide chains: (UHS MDCAT 2017)

  1. 1
  2. 2
  3. 3
  4. 4
Show answer

Correct answer: (d) 4

An antibody has two light chains and two heavy chains.

39.To combat the active infections of tetanus, rabies and snakes the _______ method of immunization is used: (UHS MDCAT 2016)

  1. Active
  2. Humoral
  3. Active Artificial
  4. Passive
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Correct answer: (d) Passive

Ready made antitoxin is injected, so the immunity is passive and acts at once.

40.The type of immunity in which antibodies are passed from one individual to another is called: (UHS MDCAT 2016)

  1. Passive Immunity
  2. Artificial Active Immunity
  3. Natural Active Immunity
  4. Humoral Immunity
Show answer

Correct answer: (a) Passive Immunity

Antibodies received ready made give passive immunity.

41.Variable amino acid sequences in antibody molecule are found in ________. (UHS MDCAT 2016)

  1. Both light chains only
  2. Both heavy chains only
  3. One heavy and one light chain
  4. Both heavy and light chains
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Correct answer: (d) Both heavy and light chains

Both the heavy and the light chains have a variable region, and together they make the binding site.

42.B-cells release antibodies in blood plasma, tissue fluid and lymph. This kind of immune response is called: (UHS MDCAT 2016)

  1. Cell Mediated Response
  2. Humoral Response
  3. Active Response
  4. Compound Response
Show answer

Correct answer: (b) Humoral Response

Immunity carried by antibodies in the body fluids is the humoral response.

43.In antibody molecule, two heavy and two light chains are bonded by: (UHS MDCAT 2016)

  1. Disulphide Bond
  2. Monosulphide Bond
  3. Hydrogen Bond
  4. Ionic Bond
Show answer

Correct answer: (a) Disulphide Bond

The four chains of an antibody are held by disulphide bridges.

44.In response, β-cells produce plasma cells that synthesize antibodies and release in blood plasma and tissue fluid. (UHS MDCAT 2015)

  1. Cell-Mediated
  2. Hormonal
  3. Humoral
  4. Phototactic
Show answer

Correct answer: (c) Humoral

Antibodies released into the body fluids carry the humoral response.

45.B-lymphocytes are named due to their relationship with: (UHS MDCAT 2015)

  1. Blood
  2. Bursa of Fabricius
  3. Bone Marrow
  4. Bile Duct
Show answer

Correct answer: (b) Bursa of Fabricius

B cells were first found maturing in the bursa of Fabricius of the bird.

46.Response of body against the transplanted organ is: (UHS MDCAT 2015)

  1. Homeostatic Response
  2. Behavioral Response
  3. Primary Response
  4. Cell-mediated Response
Show answer

Correct answer: (d) Cell-mediated Response

The graft is attacked by T lymphocytes, so the rejection is cell mediated.

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