Cellular I mmunology – 40 MCQs | Kenya MBChB

40 Year 2: Cellular Immunology exam questions on Cellular I mmunology for medical students. Includes MCQs, answers, explanations and written questions. Sample:

This MCQ set contains 40 questions on Cellular I mmunology in the Year 2: Cellular Immunology unit. Each question includes the correct answer and a detailed explanation for active recall and exam preparation.

Q1: The ability of an organism to resist infections by the pathogens is called

  1. A. Infection
  2. B. Hypersensitivity
  3. C. Immunity
  4. D. Allergy
  5. E. Attenuation

Correct answer: C – Immunity

Immunity is the body's natural defense mechanism against pathogenic microorganisms, toxins, and other harmful substances. ---

Q2: Name the group of pattern recognition molecules which functions exclusively as a signaling receptor

  1. A. CRP
  2. B. Toll-like receptor
  3. C. MBL
  4. D. LPS
  5. E. MMLS

Correct answer: B – Toll-like receptor

Toll-like receptors (TLRs) are pattern recognition receptors that recognize PAMPs and function exclusively as signaling receptors. ---

Q3: Name the first cells which are recruited at the place of infection

  1. A. NK cells
  2. B. Basophils
  3. C. Neutrophils
  4. D. Macrophages
  5. E. A and B

Correct answer: C – Neutrophils

Neutrophils are the first immune cells to arrive at the site of infection during acute inflammation. ---

Q4: Which of the following antibody gives a primary immune reaction

  1. A. IgG
  2. B. IgM
  3. C. IgA
  4. D. IgE
  5. E. A and B

Correct answer: B – IgM

IgM is the first antibody produced during a primary immune response and is most effective at complement activation. ---

Q5: Which of these is NOT a characteristic feature of adaptive immunity

  1. A. Immunogenic memory
  2. B. Antigen non-specific
  3. C. Self/non-self recognition
  4. D. Diversity
  5. E. None of the above

Correct answer: B – Antigen non-specific

Adaptive immunity is highly antigen-specific, unlike innate immunity which is non-specific. ---

Q6: The major role of the complement system is to work in conjunction with

  1. A. Antibodies to lyse cells via the C8 and C9 components
  2. B. Antibodies to lyse cells via the perforin molecules
  3. C. Antibodies to opsonize cells
  4. D. The major histocompatibility complex for cell recognition
  5. E. The T-cell receptor for production of lymphokines

Correct answer: A – Antibodies to lyse cells via the C8 and C9 components

The complement system works with antibodies to form the membrane attack complex (MAC) using C5b-C9 components. ---

Q7: One principal function of complement is to

  1. A. Bind antibodies attached to cell surfaces and to lyse these cells
  2. B. Cross-link allergens
  3. C. Inactivate perforins
  4. D. Mediate the release of histamine
  5. E. Phagocytize antigens

Correct answer: A – Bind antibodies attached to cell surfaces and to lyse these cells

The complement system binds to antibodies on target cells and forms MAC to lyse the cells. ---

Q8: Complement component C3 is cleaved by

  1. A. C3bB
  2. B. C3bBb
  3. C. Factor B
  4. D. Factor D
  5. E. Factor H

Correct answer: B – C3bBb

C3bBb is the C3 convertase of the alternative pathway that cleaves C3 into C3a and C3b. ---

Q9: The membrane attack complex in the complement pathway consists of

  1. A. C3b3b, Bb
  2. B. C5b,6,7,8,9
  3. C. Colicins
  4. D. OH
  5. E. Properdin

Correct answer: B – C5b,6,7,8,9

The membrane attack complex (MAC) is formed by complement components C5b, C6, C7, C8, and C9. ---

Q10: Acute inflammation can be initiated by

  1. A. An increase in vascular permeability
  2. B. C3
  3. C. Influx of neutrophils
  4. D. Lysozyme
  5. E. Mast cell activation

Correct answer: E – Mast cell activation

Mast cell activation releases inflammatory mediators like histamine, which initiate acute inflammation. ---

Q11: Clonal selection occurs when antigen is encountered by

  1. A. Basophils
  2. B. Eosinophils
  3. C. Mast cells
  4. D. Neutrophils
  5. E. T-cell

Correct answer: E – T-cell

Clonal selection is the process where specific T cells that recognize a particular antigen are selected for proliferation. ---

Q12: Complement component C3b

  1. A. Directly injures bacteria
  2. B. Is an anaphylatoxin
  3. C. Is chemotactic
  4. D. Is the inactive form of C3
  5. E. Opsonizes bacteria

Correct answer: E – Opsonizes bacteria

C3b is a major opsonin that coats bacteria, marking them for phagocytosis by immune cells. ---

Q13: Naturally acquired active immunity would be most likely acquired through which of the following processes

  1. A. Vaccination
  2. B. Drinking colostrum
  3. C. Natural birth
  4. D. Infection with disease-causing organism followed by recovery
  5. E. Both A and C

Correct answer: D – Infection with disease-causing organism followed by recovery

Naturally acquired active immunity occurs when the immune system responds to a natural infection. ---

Q14: Which of the following convey the longest-lasting immunity to an infectious agent

  1. A. Naturally acquired passive immunity
  2. B. Artificially acquired passive immunity
  3. C. Naturally acquired active immunity
  4. D. All of these
  5. E. None of these

Correct answer: C – Naturally acquired active immunity

Naturally acquired active immunity provides the longest-lasting protection through memory cell development. ---

Q15: Which of the following substances will not stimulate an immune response unless they are bound to a larger molecule

  1. A. Antigen
  2. B. Virus
  3. C. Hapten
  4. D. Mitogen
  5. E. Antibody

Correct answer: C – Hapten

Haptens are small molecules that become immunogenic only when conjugated to larger carrier molecules. ---

Q16: B and T cells are produced by stem cells that are formed in

  1. A. Bone marrow
  2. B. The liver
  3. C. The circulatory system
  4. D. The spleen
  5. E. The lymph nodes

Correct answer: A – Bone marrow

Hematopoietic stem cells in the bone marrow give rise to all blood cells, including B and T cell precursors. ---

Q17: B cells mature in the....... while T cells mature in the........

  1. A. Thymus/bone marrow and gut-associated lymphoid tissue (GALT)
  2. B. Spleen/bone marrow and GALT
  3. C. Bone marrow and GALT/Thymus
  4. D. Liver/Kidneys

Correct answer: C – Bone marrow and GALT/Thymus

B cells mature in bone marrow and GALT, while T cells migrate to and mature in the thymus. ---

Q18: Which of the following immune cells/molecules are most effective at destroying intracellular pathogens

  1. A. T helper cells
  2. B. B cells
  3. C. Antibodies
  4. D. Complement
  5. E. T cytolytic cells

Correct answer: E – T cytolytic cells

T cytolytic cells (CD8+ T cells) are specialized to kill cells infected with intracellular pathogens. ---

Q19: A living microbe with reduced virulence that is used for vaccination is considered

  1. A. A toxoid
  2. B. Dormant
  3. C. Virulent
  4. D. Attenuated
  5. E. Denatured

Correct answer: D – Attenuated

Attenuated microorganisms are live pathogens that have been weakened to stimulate immunity without causing disease. ---

Q20: B cells that produce and release large amounts of antibody are called

  1. A. Memory cells
  2. B. Basophils
  3. C. Plasma cells
  4. D. Killer cells
  5. E. Neutrophils

Correct answer: C – Plasma cells

Plasma cells are differentiated B cells specialized for antibody production. ---

Q21: The specificity of an antibody is due to

  1. A. Its valence
  2. B. The heavy chains
  3. C. The Fc portion of the molecule
  4. D. The variable portion of the heavy and light chain
  5. E. A and B

Correct answer: D – The variable portion of the heavy and light chain

The variable regions of both heavy and light chains form the antigen-binding site, determining antibody specificity. ---

Q22: In agglutination reactions, the antigen is a....... in precipitation reactions, the antigen is a......

  1. A. whole cell/soluble molecule
  2. B. Soluble molecule/whole cell
  3. C. Bacterium/virus
  4. D. Protein/carbohydrates
  5. E. Protein/Antibody

Correct answer: A – whole cell/soluble molecule

Agglutination involves clumping of whole cells, while precipitation involves soluble antigens. ---

Q23: B Cells are activated by

  1. A. Complement
  2. B. Antibody
  3. C. Interferon
  4. D. Memory cells
  5. E. Antigen

Correct answer: E – Antigen

B cells are activated when their surface immunoglobulin receptors bind to specific antigens. ---

Q24: Fusion between a plasma cell and a tumor cell creates a

  1. A. Myeloma
  2. B. Natural killer cell
  3. C. Lymphoblast
  4. D. Lymphoma
  5. E. Hybridoma

Correct answer: E – Hybridoma

Hybridomas are created by fusing plasma cells with tumor cells to produce monoclonal antibodies. ---

Q25: Monoclonal antibodies recognize a single

  1. A. Antigen
  2. B. Bacterium
  3. C. Epitope
  4. D. B cell
  5. E. Virus

Correct answer: C – Epitope

Monoclonal antibodies are produced by identical B cell clones and recognize a single specific epitope. ---

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