Free Immunology MCQs with Answers
90 Immunology MCQs from Microbiology, each with the correct answer and a written explanation of why it is correct. Free and unlimited, with no account needed.
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- A. Less sensitive less specific
- B. More sensitive, more specific
- C. Less sensitive, more specific
- D. More sensitive, less specific
Explanation: ELISA is generally more sensitive but less specific than Western blot, making it useful for screening but more prone to false-positive…
Correct answer: More sensitive, less specific- A. Helper T lymphocytes
- B. Natural killer cells
- C. Plasma cells
- D. Macrophages
Explanation: HIV progressively damages CD4 helper T lymphocytes, which coordinate both cellular and humoral immune responses.
Correct answer: Helper T lymphocytes- A. 2:1
- B. 1:2
- C. 3:1
- D. 1:3
Explanation: In healthy adults, CD4 helper T cells usually outnumber CD8 cytotoxic T cells, giving a CD4:CD8 ratio of about 2:1.
Correct answer: 2:1- A. 500
- B. 200
- C. 1000
- D. 300
Explanation: A normal adult CD4 count is broadly about 500 to 1500 cells per microlitre, with approximately 1000 as a commonly cited average.
Correct answer: 1000- A. Allo
- B. ISO
- C. Xeno
- D. Auto
Explanation: A kidney transferred between two genetically different members of the same species is an allograft, also called an allogeneic graft.
Correct answer: Allo- A. Adjuvant
- B. Proteins
- C. Polysaccharides
- D. Lipids
Explanation: Proteins are the most potent immunogens because they contain complex structures that stimulate both antibody production and T-cell…
Correct answer: Proteins- A. Anaphylaxis
- B. Arthus reaction
- C. Serum sickness
- D. Contact dermatitis
Explanation: In serum sickness, one large antigen dose can provide the initial sensitisation and later produce immune-complex disease as antibody…
Correct answer: Serum sickness- A. Severe reaction following the injection of protein solution in a sensitized individual
- B. Severe reaction following primary injection of Protein solutions
- C. State of immunity developed by repeated injections of any foreign substance
- D. Severe reaction resulting from sensitivity to common allergens
Explanation: Anaphylaxis is a severe, usually immediate systemic reaction that occurs when a previously sensitised person is re-exposed to an antigen…
Correct answer: Severe reaction following the injection of protein solution in a sensitized individual- A. NK Cells
- B. Cytotoxic T cells
- C. B cells
- D. Memory B cells
Explanation: Natural killer cells are innate lymphocytes that destroy virus-infected cells without prior antigen-specific sensitisation.
Correct answer: NK Cells- A. IL-1
- B. IL-6
- C. IL-8
- D. TNF
Explanation: IL-8, also called CXCL8, is a chemokine that attracts neutrophils to sites of infection and inflammation.
Correct answer: IL-8- A. Active
- B. Passive
- C. Herd
- D. Local
Explanation: The negative phase is classically described in active immunisation, when pre-existing antibody may temporarily fall or neutralise the…
Correct answer: Active- A. Atopy
- B. Anaphylaxis
- C. Arthus phenomenon
- D. Serum sickness
Explanation: The Arthus phenomenon is a local immune-complex reaction in a previously sensitised animal, causing oedema, haemorrhage and necrosis at…
Correct answer: Arthus phenomenon- A. Anaphylaxis
- B. Delayed hypersensitivity
- C. Immune complex mediated
- D. Cytotoxic / cytolytic type
Explanation: Type II hypersensitivity is antibody-mediated cytotoxicity, in which IgG or IgM binds antigens on cell surfaces and activates complement…
Correct answer: Cytotoxic / cytolytic type- A. CD7+ Pro-T-Cells
- B. CD5+ Pre-T-Cells
- C. CD8+ Pro-T-Cells
- D. CD8+ Pre-T-Cells
Explanation: CD7 is the earliest reliable T-lineage marker and appears on pro-T cells before the later CD4 or CD8 stages.
Correct answer: CD7+ Pro-T-Cells- A. IgE
- B. IgM
- C. IgA
- D. IgG
Explanation: IgE does not normally activate the complement system, unlike IgM and most IgG, which are important classical-pathway antibodies.
Correct answer: IgE- A. IgG
- B. IgA
- C. IgD
- D. IgE
Explanation: IgE is the reaginic antibody responsible for immediate hypersensitivity and binds to mast cells and basophils.
Correct answer: IgE- A. IgG
- B. IgA
- C. IgM
- D. IgE
Explanation: Secondary immune responses are dominated by IgG produced rapidly by memory B cells, making them stronger and longer-lasting than primary…
Correct answer: IgG- A. Secretory piece
- B. H chain
- C. L chain
- D. J piece
Explanation: The immunoglobulin heavy chain has a molecular weight of about 50,000 to 75,000 daltons, whereas a light chain is approximately 25,000…
Correct answer: H chain- A. B cells
- B. T cells
- C. Monocytes
- D. Macrophage
Explanation: Helper cells are CD4-positive T cells and killer cells are cytotoxic CD8-positive T cells, so both belong to the T-cell population.
Correct answer: T cells- A. Macrolin
- B. Heat
- C. Bovine serum
- D. Phytohaemagglutinin
Explanation: Phytohaemagglutinin is a plant lectin that acts as a polyclonal T-cell mitogen, causing T-cell activation and multiplication.
Correct answer: PhytohaemagglutininImmunology MCQs: common questions
Are these Immunology MCQs free?
Yes. All Immunology MCQs from Microbiology are free on TestUstad, with unlimited attempts and no account needed. Nothing on this page is a sample or a trial.
How many Immunology MCQs are on this page?
There are 90 Immunology MCQs in the Microbiology bank, shown 20 to a page with the correct answer and an explanation on each.
Does every Immunology MCQ have an explanation?
Yes. Each Immunology question shows the correct option and a written explanation of why it is correct, so a wrong answer teaches you something rather than just being marked wrong.
Can I take a timed Immunology test?
Yes. The practice button on this page starts a free Immunology test drawn from the Microbiology bank. It marks each answer instantly, gives you a score at the end, and can be retaken as many times as you like.