Unit 4: Major histocompatibility complex; T and B lymphocytes - Practice Quiz

1 What does the abbreviation MHC stand for?

2 In humans, the MHC is also known as the:

3 On which human chromosome is the MHC gene complex located?

4 Which cells recognize antigens presented by MHC class I molecules?

5 MHC class II molecules primarily present antigens to which cell type?

6 Which of the following is an example of a human MHC class I gene?

7 MHC class I molecules are expressed on:

8 MHC class II molecules are mainly expressed on:

9 Which of the following cells does not express MHC class I molecules?

10 Endogenous (intracellular) antigens are typically presented by which MHC class?

11 Exogenous antigens taken up from outside the cell are processed and presented mainly by:

12 Which cellular organelle degrades endogenous proteins into peptides for MHC class I presentation?

13 The B cell receptor (BCR) is essentially a membrane-bound form of which molecule?

14 Which cells provide help to B cells during their activation against protein antigens?

15 Upon full activation, B cells differentiate into which antibody-secreting cells?

16 Most T-cell receptors (TCRs) are composed of which two polypeptide chains?

17 Unlike antibodies, the T-cell receptor recognizes antigen only when it is:

18 In which organ do T cells undergo maturation?

19 The process that eliminates T cells reacting strongly against self-antigens is called:

20 In mammals, where does the early maturation of B cells primarily occur?

21 A researcher observes that a set of genes on the same chromosome are inherited together as a unit and encode molecules critical for antigen presentation. This inheritance pattern is best described as a:

22 MHC molecules are highly polymorphic in a population. What is the primary immunological advantage of this polymorphism at the population level?

23 A peptide of 9 amino acids fits snugly into a closed-ended binding groove of an MHC molecule. This structural feature is characteristic of which MHC class?

24 Which structural comparison correctly distinguishes MHC class I from MHC class II molecules?

25 A virus infects a hepatocyte (liver cell). Which MHC molecule will most likely present the viral peptides to alert the immune system?

26 Which set of cells constitutively expresses high levels of MHC class II molecules?

27 A cytosolic protein is degraded and its peptides are eventually loaded onto MHC class I. Which pathway component is responsible for transporting these peptides into the endoplasmic reticulum?

28 The invariant chain (Ii) associates with newly synthesized MHC class II in the ER. What is its primary function?

29 A macrophage engulfs an extracellular bacterium. Where does the antigenic peptide most likely bind to its presenting MHC molecule?

30 The role of HLA-DM in the MHC class II pathway is best described as:

31 The B cell receptor (BCR) itself has a very short cytoplasmic tail and cannot signal alone. Which associated proteins transmit the activation signal into the cell?

32 A B cell responds to a protein antigen but requires additional signals to become fully activated and undergo class switching. Which interaction provides this second signal?

33 Thymus-independent type 2 (TI-2) antigens, such as bacterial polysaccharides, activate B cells primarily by:

34 Unlike the B cell receptor, the majority of T-cell receptors recognize antigen only when it is:

35 The CD3 complex is essential for T-cell receptor function. Its main role is to:

36 A helper T cell recognizes a peptide-MHC class II complex. Which coreceptor stabilizes this interaction, and what does it bind?

37 During T-cell maturation in the thymus, a thymocyte that expresses both CD4 and CD8 is at which developmental stage?

38 A double-positive thymocyte whose TCR binds self peptide-MHC with very high affinity is eliminated. This process is called:

39 A thymocyte fails to bind any self-MHC molecule with sufficient affinity during positive selection. What is its most likely fate?

40 During B-cell development in the bone marrow, successful rearrangement of the heavy-chain gene and expression of the pre-B cell receptor signals the cell to:

41 A viral protein is synthesized in the cytosol of an infected fibroblast. The proteasome generates peptides that are transported into the ER via TAP. Which combination of events must occur for successful surface presentation?

42 A thymocyte expresses a TCR that binds self-peptide-MHC with intermediate affinity in the cortex but with high affinity when encountering the same complex on medullary dendritic cells. What is the fate of this thymocyte?

43 Which structural feature distinguishes the peptide-binding capacity of MHC class II from class I molecules?

44 A researcher finds a nucleated somatic cell lacking surface MHC class I. Which functional consequence and cellular interaction is most predictable?

45 The diversity of the TCR chain differs from the chain primarily because:

46 A B cell binds a soluble protein antigen but receives no T-cell help. Under most physiological conditions, what is the likely outcome?

47 Cross-presentation allows dendritic cells to present exogenous antigen on MHC class I. Which mechanism best explains this pathway?

48 During T-cell development, the pre-TCR complex signals a critical checkpoint. What does successful pre-TCR signaling accomplish at the DN3 stage?

49 The transcription factor AIRE is expressed in medullary thymic epithelial cells. A loss-of-function AIRE mutation would most directly cause:

50 MHC polymorphism is concentrated in specific regions of the molecule. Where do the most variable residues cluster and why?

51 An immature B cell in the bone marrow strongly binds a multivalent self-antigen. Which tolerance mechanism is triggered first, and what is a possible rescue outcome?

52 The BCR signaling complex requires accessory molecules for signal transduction. What roles do and (CD79a/b) play?

53 The invariant chain (Ii) and CLIP peptide regulate MHC class II loading. What is the function of HLA-DM in this pathway?

54 A TCR recognizes a peptide-MHC complex, but signal transduction fails despite normal TCR expression. A defect in which associated structure is the most likely cause?

55 Which statement correctly contrasts the constitutive tissue distribution of MHC class I and class II molecules?

56 How is CD4 versus CD8 lineage commitment determined during positive selection of double-positive thymocytes?

57 As a developing B cell progresses from pro-B to pre-B stage, which molecular event marks the pre-B checkpoint?

58 MHC class III genes are located within the MHC locus but differ functionally from class I and II. Which products are encoded by class III genes?

59 MHC alleles are expressed codominantly. For a heterozygous individual at the three classical class I loci (HLA-A, -B, -C), how many distinct classical class I molecules can potentially be expressed?

60 Estimates suggest the vast majority of developing thymocytes die during selection. Which combination best explains this high attrition?