TRB PG Assistant - Lymphoid organs, MHC molecules, B and T cell activation Online Test (MCQ Quiz)

1. Which of the following is considered a primary lymphoid organ?

A) Spleen B) Lymph nodes C) Thymus D) Peyer's patches

2. What is the primary function of the thymus in the immune system?

A) Production of antibodies B) Maturation of T lymphocytes C) Filtration of lymph D) Storage of B lymphocytes

3. Which cells are responsible for the development and maturation of B lymphocytes?

A) Thymocytes B) Plasma cells C) Bone marrow stromal cells D) Reticular cells

4. Lymph nodes are secondary lymphoid organs that filter lymph and house immune cells. Which of the following is a major function of lymph nodes?

A) Production of erythrocytes B) Site of T cell proliferation upon antigen exposure C) Primary site of B cell differentiation D) Maturation of natural killer cells

5. Peyer's patches are lymphoid tissues found in the small intestine. What is their primary role?

A) Producing hormones B) Monitoring intestinal pathogens C) Regenerating intestinal epithelium D) Absorbing nutrients

6. The spleen is a secondary lymphoid organ. What is its main function related to blood?

A) Producing red blood cells in adults B) Filtering blood and removing old erythrocytes C) Storing platelets exclusively D) Synthesizing bile

7. MHC stands for Major Histocompatibility Complex. What is the main function of MHC molecules?

A) Transporting oxygen in the blood B) Presenting peptide antigens to T cells C) Catalyzing enzymatic reactions D) Binding to hormones

8. MHC Class I molecules are found on most nucleated cells. Which type of T cell primarily interacts with MHC Class I molecules?

A) Helper T cells B) Regulatory T cells C) Cytotoxic T cells D) B cells

9. MHC Class II molecules are primarily found on antigen-presenting cells (APCs). Which type of T cell primarily interacts with MHC Class II molecules?

A) Cytotoxic T cells B) Helper T cells C) Gamma delta T cells D) Natural killer T cells

10. What type of antigen is typically presented by MHC Class I molecules?

A) Exogenous antigens B) Endogenous antigens C) Secreted antigens D) Dietary antigens

11. What type of antigen is typically presented by MHC Class II molecules?

A) Endogenous antigens B) Viral antigens replicating inside cells C) Exogenous antigens D) Self-antigens

12. Which of the following is a key characteristic of B cell activation?

A) Requires direct interaction with cytotoxic T cells B) Involves recognition of antigen by the B cell receptor (BCR) C) Primarily mediated by MHC Class I molecules D) Leads to the immediate release of perforin

13. What is the role of T helper cells (CD4+ T cells) in B cell activation?

A) Directly killing infected cells B) Providing co-stimulatory signals and cytokines to B cells C) Suppressing B cell proliferation D) Presenting antigens to B cells

14. What is the primary outcome of B cell activation and differentiation?

A) Production of cytotoxic T lymphocytes B) Maturation into plasma cells that secrete antibodies C) Development into memory T cells D) Induction of apoptosis in target cells

15. Which co-receptor molecule on T cells plays a crucial role in recognizing MHC Class II molecules?

A) CD8 B) CD4 C) CD3 D) CD19

16. Which co-receptor molecule on T cells plays a crucial role in recognizing MHC Class I molecules?

A) CD4 B) CD8 C) CD28 D) CD40

17. T cell activation requires two signals: Signal 1 is the T cell receptor (TCR) binding to the peptide-MHC complex. What is Signal 2?

A) Cytokine signaling B) Co-stimulatory signals (e.g., B7-CD28 interaction) C) Antibody binding D) Complement activation

18. Which of the following is a characteristic of T cell tolerance induction in the thymus?

A) Clonal deletion of self-reactive T cells B) Clonal expansion of self-reactive T cells C) Production of autoantibodies D) Upregulation of pro-inflammatory cytokines

19. Which molecule is crucial for antigen processing and presentation by MHC Class II molecules?

A) Ubiquitin B) Invariant chain (Ii) C) Proteasome D) Calnexin

20. The process by which immature T cells that recognize self-antigens strongly in the thymus are eliminated is called:

A) Positive selection B) Negative selection C) Affinity maturation D) Isotype switching

21. What is the term for the process where T cells that can recognize self-MHC molecules are positively selected in the thymus?

A) Negative selection B) Central tolerance C) Positive selection D) Peripheral tolerance

22. Which molecule is primarily involved in the interaction between B cells and T helper cells during T-dependent B cell activation?

A) CD40L on T cells and CD40 on B cells B) CD80 on T cells and CD28 on B cells C) MHC Class I on T cells and TCR on B cells D) IL-2 receptor on T cells and IL-2 on B cells

23. What is the function of the proteasome in antigen presentation?

A) Degrades proteins in the cytoplasm into peptides for MHC Class I presentation B) Degrades proteins in endosomes for MHC Class II presentation C) Synthesizes MHC molecules D) Transports peptides into the endoplasmic reticulum

24. Which organelle is primarily involved in the loading of peptides onto MHC Class I molecules?

A) Golgi apparatus B) Lysosome C) Endoplasmic reticulum D) Mitochondrion

25. Which molecule facilitates the transport of antigenic peptides from the cytoplasm into the endoplasmic reticulum for loading onto MHC Class I molecules?

A) TAP (Transporter associated with antigen processing) B) CLIP (Class II-associated invariant chain peptide) C) Calreticulin D) HSP70

26. What is the role of invariant chain (Ii) in MHC Class II pathway?

A) It binds to peptides in the cytoplasm B) It blocks the peptide-binding groove of MHC Class II molecules in the ER C) It facilitates peptide loading in the ER D) It is a co-stimulatory molecule for T cell activation

27. Which of the following is a characteristic of T-independent B cell activation?

A) Requires help from T helper cells B) Leads to the generation of memory B cells C) Typically triggered by repetitive epitopes on antigens like bacterial polysaccharides D) Results in the production of IgG antibodies

28. What is the primary function of the CD3 complex associated with the T cell receptor (TCR)?

A) Antigen binding B) Signal transduction upon TCR activation C) Co-stimulation D) Adhesion to antigen-presenting cells

29. Which cells are considered professional antigen-presenting cells (APCs)?

A) Erythrocytes, platelets, and basophils B) Neurons, hepatocytes, and muscle cells C) Dendritic cells, macrophages, and B cells D) Mast cells, eosinophils, and neutrophils

30. What is the primary role of dendritic cells in the immune response?

A) Producing antibodies B) Phagocytosing pathogens and presenting antigens to T cells C) Killing infected host cells D) Releasing histamine

31. Which molecule is primarily responsible for the binding of T cells to antigen-presenting cells via MHC Class I?

A) CD4 B) CD8 C) CD28 D) CTLA-4

32. Which molecule is primarily responsible for the binding of T cells to antigen-presenting cells via MHC Class II?

A) CD8 B) CD4 C) LFA-1 D) ICAM-1

33. What is the significance of co-stimulatory molecules like B7 (CD80/CD86) on APCs for T cell activation?

A) They inhibit T cell activation B) They provide the second signal necessary for full T cell activation, preventing anergy C) They bind directly to antibodies D) They are involved in antigen processing

34. What is the term for the state of unresponsiveness of T cells to an antigen, often resulting from the absence of co-stimulatory signals?

A) Activation B) Proliferation C) Anergy D) Differentiation

35. Which cytokine is crucial for the differentiation of naive T cells into T helper 1 (Th1) cells?

A) IL-4 B) IL-10 C) IFN-gamma D) TGF-beta

36. Which cytokine is primarily involved in the differentiation of naive T cells into T helper 2 (Th2) cells?

A) IFN-gamma B) IL-4 C) IL-17 D) IL-12

37. What is the function of T regulatory cells (Tregs)?

A) To initiate inflammatory responses B) To suppress immune responses and maintain self-tolerance C) To directly kill infected cells D) To produce antibodies

38. Which transcription factor is essential for the development and function of T helper 17 (Th17) cells?

A) T-bet B) GATA3 C) ROR-gamma-t D) FoxP3

39. Which transcription factor is essential for the development and function of T regulatory cells (Tregs)?

A) T-bet B) GATA3 C) ROR-gamma-t D) FoxP3

40. What is the role of the spleen in filtering blood?

A) Removing bacteria and viruses from the blood B) Removing aged and damaged red blood cells C) Removing metabolic waste products D) Removing excess electrolytes

41. Which part of the thymus is primarily responsible for T cell maturation?

A) Cortex B) Medulla C) Capsule D) Trabeculae

42. In the context of B cell activation, what is somatic hypermutation?

A) A process that increases the diversity of TCRs B) A process that increases the affinity of antibodies for their antigens C) A process that leads to T cell anergy D) A process that degrades endogenous antigens

43. What is isotype switching in B cells?

A) The process of B cell receptor rearrangement B) The change in the heavy chain constant region of an antibody, altering its effector function C) The selection of B cells that recognize self-antigens D) The migration of B cells to lymph nodes

44. Which MHC class is involved in presenting antigens to CD8+ T cells?

A) MHC Class I B) MHC Class II C) MHC Class III D) MHC Class IV

45. Which MHC class is involved in presenting antigens to CD4+ T cells?

A) MHC Class I B) MHC Class II C) MHC Class III D) MHC Class IV

46. The process of T cell development in the thymus involves the expression of T cell receptor (TCR) and co-receptors. What is the minimum requirement for a T cell to survive positive and negative selection?

A) Ability to bind strongly to self-MHC and self-peptide B) Ability to bind weakly to self-MHC and weakly to self-peptide C) Ability to bind strongly to foreign peptide presented by self-MHC D) Ability to bind strongly to self-peptide presented by foreign MHC

47. Which of the following is a crucial component of the B cell receptor (BCR) complex besides the membrane-bound immunoglobulin?

A) CD3 complex B) Igα/Igβ heterodimer C) CD4 co-receptor D) TCR

48. What is the primary role of the lymph nodes in the adaptive immune response?

A) Producing hormones B) Site for encounter between lymphocytes and antigens, leading to activation C) Filtering blood D) Generating red blood cells

49. The antigen-binding site of an antibody is formed by the variable regions of which chains?

A) Heavy chains only B) Light chains only C) Both heavy and light chains D) Constant regions of heavy and light chains

50. Which statement best describes the function of cytotoxic T lymphocytes (CTLs)?

A) They help B cells produce antibodies. B) They present antigens to helper T cells. C) They recognize and kill virus-infected cells and tumor cells. D) They suppress the immune response.

Lymphoid organs, MHC molecules, B and T cell activation - Online Test

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