TRB PG Assistant - Immunology – innate and adaptive immunity, antigens, antibodies, diversity Online Test (MCQ Quiz)

1. Which component of the innate immune system acts as a physical barrier against pathogens?

A) Complement proteins B) Phagocytic cells C) Skin and mucous membranes D) Natural Killer cells

2. What is the primary function of phagocytic cells like macrophages and neutrophils in innate immunity?

A) Producing antibodies B) Recognizing and engulfing pathogens C) Mediating allergic reactions D) Suppressing immune responses

3. Which of the following is a key characteristic of adaptive immunity?

A) Rapid, non-specific response B) Memory and specificity C) Absence of lymphocytes D) Immediate reaction upon first exposure

4. What is an antigen?

A) A type of white blood cell B) A molecule that elicits an immune response C) An antibody-producing cell D) A signaling molecule of the immune system

5. Which type of immune cell is primarily responsible for producing antibodies?

A) T helper cells B) Cytotoxic T lymphocytes C) Plasma cells (differentiated B cells) D) Macrophages

6. What is the main role of T helper cells (CD4+ T cells) in adaptive immunity?

A) Directly killing infected cells B) Suppressing immune responses C) Activating B cells and cytotoxic T cells D) Engulfing pathogens

7. Cytotoxic T lymphocytes (CTLs) are primarily involved in which type of immune response?

A) Humoral immunity B) Cell-mediated immunity against infected cells C) Allergic reactions D) Complement activation

8. Which class of antibodies is the most abundant in serum and is crucial for secondary immune responses?

A) IgA B) IgE C) IgG D) IgM

9. What is the function of IgA antibodies?

A) Mediating allergic reactions B) Found in secretions like tears, saliva, and milk C) Primary response antibody D) Crosses the placenta

10. Which antibody is primarily involved in allergic reactions and defense against parasitic worms?

A) IgG B) IgM C) IgA D) IgE

11. What is immunological memory?

A) The ability of the immune system to forget past infections B) A rapid and enhanced response upon re-exposure to an antigen C) The initial non-specific defense against pathogens D) The process of antigen presentation

12. The diversity of antibodies produced by B cells is generated through which genetic mechanism?

A) Gene duplication B) Somatic recombination (V(D)J recombination) C) Epigenetic modifications D) RNA splicing

13. Which part of an antibody molecule binds to an antigen?

A) Fc region B) Heavy chain constant region C) Fab region (variable region) D) J chain

14. Opsonization is a process where antibodies or complement proteins coat a pathogen, enhancing its recognition and engulfment by phagocytes. Which antibody is particularly effective at opsonization?

A) IgM B) IgE C) IgA D) IgG

15. What is the role of MHC (Major Histocompatibility Complex) molecules in adaptive immunity?

A) Producing antibodies B) Presenting antigen fragments to T cells C) Directly killing pathogens D) Generating immunological memory

16. Which cells express MHC Class I molecules?

A) Only B cells B) Only antigen-presenting cells C) All nucleated cells D) Only red blood cells

17. MHC Class II molecules are typically found on which type of cells?

A) Red blood cells B) All nucleated cells C) Antigen-presenting cells (APCs) like macrophages and dendritic cells D) Neurons

18. What is the primary function of cytokines in the immune system?

A) Directly binding and neutralizing toxins B) Acting as signaling molecules to regulate immune cell activity C) Forming the physical barrier of the skin D) Generating antibody diversity

19. Which of the following is an example of an innate immune cell that releases cytotoxic granules to kill infected cells and tumor cells?

A) B lymphocyte B) Plasma cell C) Natural Killer (NK) cell D) Memory T cell

20. The inflammatory response is a key part of innate immunity. Which of the following is a cardinal sign of inflammation?

A) Pallor (paleness) B) Calor (heat) C) Hypothermia D) Anesthesia

21. What is a hapten?

A) A large, complex antigen B) A small molecule that can elicit an immune response only when attached to a larger carrier molecule C) A type of antibody D) A cell involved in innate immunity

22. Which component of the complement system is central to all three pathways (classical, alternative, lectin) of complement activation?

A) C1q B) C3 C) Factor B D) Mannose-binding lectin

23. What is the function of the membrane attack complex (MAC) formed by the complement system?

A) To neutralize toxins B) To facilitate phagocytosis C) To create pores in the pathogen's membrane, leading to lysis D) To recruit inflammatory cells

24. Which type of T cell recognizes antigens presented on MHC Class I molecules?

A) T helper cells (CD4+) B) Regulatory T cells (Tregs) C) Cytotoxic T lymphocytes (CD8+) D) B cells

25. Which type of T cell recognizes antigens presented on MHC Class II molecules?

A) Cytotoxic T lymphocytes (CD8+) B) T helper cells (CD4+) C) NK cells D) Plasma cells

26. What is the function of B memory cells?

A) To immediately produce antibodies upon initial exposure B) To reside in lymphoid organs and provide a rapid and enhanced antibody response upon secondary exposure C) To directly kill infected cells D) To suppress the immune response

27. What is the role of T regulatory cells (Tregs)?

A) To activate other immune cells B) To suppress immune responses and maintain self-tolerance C) To produce antibodies D) To engulf pathogens

28. Which antibody is the first to be produced during a primary immune response?

A) IgG B) IgA C) IgM D) IgE

29. What is autoimmunity?

A) An overactive immune response to harmless environmental substances B) The immune system attacking the body's own tissues C) A deficiency in antibody production D) A failure of innate immune mechanisms

30. Which of the following is a primary lymphoid organ where T lymphocytes mature?

A) Spleen B) Lymph nodes C) Thymus D) Bone marrow

31. Where do B lymphocytes mature?

A) Thymus B) Lymph nodes C) Bone marrow D) Spleen

32. What is herd immunity?

A) The immunity of a single individual to a specific pathogen B) The collective immunity of a population that reduces the likelihood of infection for individuals C) The immunity gained from vaccination only D) The innate resistance of certain species to diseases

33. Which term describes the ability of the immune system to distinguish between self and non-self antigens?

A) Immunogenicity B) Specificity C) Self-tolerance D) Affinity

34. What is the role of dendritic cells in the immune system?

A) Producing antibodies B) Acting as potent antigen-presenting cells to initiate adaptive immune responses C) Killing infected cells directly D) Suppressing T cell activity

35. Which of the following is a characteristic of adaptive immunity but NOT innate immunity?

A) Presence of phagocytic cells B) Rapid response C) Development of memory D) Inflammatory response

36. The classical pathway of complement activation is typically initiated by the binding of C1q to which of the following?

A) Pathogen surface molecules B) Antibody-antigen complexes C) Mannose-binding lectin D) Properdin

37. What is the term for an antigen that requires a carrier molecule to elicit an immune response?

A) Epitope B) Hapten C) Paratope D) Allergen

38. Which cells are primarily responsible for the destruction of virus-infected cells and tumor cells in cell-mediated immunity?

A) B cells B) T helper cells C) Plasma cells D) Cytotoxic T lymphocytes

39. What is the primary function of lysozyme, an enzyme found in tears and saliva, as part of innate immunity?

A) To neutralize viral particles B) To break down bacterial cell walls C) To signal for inflammation D) To enhance antibody binding

40. Which statement best describes the diversity of the antibody repertoire?

A) It is limited by the number of genes encoding antibody chains. B) It is generated through a combinatorial process involving gene rearrangement and junctional diversity. C) It is fixed at birth and does not change. D) It is primarily determined by somatic hypermutation alone.

41. What is the role of cytokines like interleukins and interferons?

A) To directly kill pathogens B) To signal and regulate the immune system's response C) To form physical barriers D) To store immunological memory

42. Which type of hypersensitivity reaction is mediated by IgE antibodies and involves mast cells and basophils?

A) Type I (Immediate) B) Type II (Cytotoxic) C) Type III (Immune Complex) D) Type IV (Delayed)

43. The 'innate' aspect of the immune system implies:

A) It is acquired during life and specific to pathogens. B) It is present from birth and non-specific. C) It develops after exposure to pathogens and has memory. D) It targets only intracellular pathogens.

44. What is an epitope?

A) The entire antigen molecule. B) The specific part of an antigen that is recognized by an antibody or T cell receptor. C) A molecule that suppresses the immune response. D) A type of cytotoxic T cell.

45. Which cells are responsible for producing and secreting antibodies during an active infection or after vaccination?

A) Naive B cells B) Memory B cells C) Plasma cells D) Dendritic cells

46. The phenomenon where a single B cell can produce antibodies with different affinities for an antigen over time is known as:

A) Clonal deletion B) Affinity maturation C) Central tolerance D) Immunological anergy

47. Which of the following is NOT a characteristic of adaptive immunity?

A) Specificity B) Memory C) Rapid response to first exposure D) Self-tolerance

48. What is the function of peritoneal macrophages in the innate immune system?

A) Producing antibodies B) Phagocytosing pathogens and cellular debris within the peritoneal cavity C) Presenting antigens to T cells D) Mediating allergic reactions

49. Which component of the adaptive immune system provides long-lasting protection against specific pathogens after an infection or vaccination?

A) Innate immune cells B) Antibodies produced by short-lived plasma cells C) Immunological memory (memory B and T cells) D) Inflammatory mediators

Immunology – innate and adaptive immunity, antigens, antibodies, diversity - Online Test

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