Maximum score: 94%
Minimum score: 28%
Approximate scale:
94-89 = A
88-81 = B
80-57 = C
56-48 = D
47-28 = F
| Average score: 75.6% Maximum score: 94% Minimum score: 28% Approximate scale: 94-89 = A 88-81 = B 80-57 = C 56-48 = D 47-28 = F |
|
Questions numbered 1 through 25 count 2 points each (50 points).
| B | 1. | (1) | The probability of finding a CD8 molecule on the surface of a helper T-cell. |
| (2) | The probability of finding a CD8 molecule on the surface of a cytotoxic T-cell. | ||
| B | 2. | (1) | The importance of macrophage activation to the elimination of extracellular bacteria. |
| (2) | The importance of macrophage activation to the elimination of intracellular bacteria. | ||
| A | 3. | (1) | The importance of opsonizing antibodies in preventing disease caused by an organism such as Streptococcus pneumoniae whose sole virulence mechanism is the production of a capsule. |
| (2) | The importance of antitoxin antibodies in preventing disease caused by an organism such as Streptococcus pneumoniae whose sole virulence mechanism is the production of a capsule. | ||
| B | 4. | (1) | The ability of IgM antibody to cross the placenta and help to protect a fetus in utero. |
| (2) | The ability of IgG antibody to cross the placenta and help to protect a fetus in utero. | ||
| B | 5. | (1) | The probability that an antigen derived from an extracellular bacterium would be presented to a T-cell via the Class I MHC molecule. |
| (2) | The probability that an antigen derived from an extracellular bacterium would be presented to a T-cell via the Class II MHC molecule. | ||
| A | 6. | (1) | The ability of a macrophage to present antigen to a T-cell. |
| (2) | The ability of a macrophage to present antigen to a B-cell. | ||
| A | 7. | (1) | The number of polypeptide chains that make up a molecule of IgM. |
| (2) | The number of polypeptide chains that make up a molecule of IgA. | ||
| B | 8. | (1) | The role of the Class II MHC molecule in the recognition of antigen. |
| (2) | The role of the Class II MHC molecule in the presentation of antigen. | ||
| C | 9. | (1) | The ability of the complement complex C3bBb to cleave the component C5. |
| (2) | The ability of the complement complex C4b2b to cleave the component C5. | ||
| B | 10. | (1) | The number of possible different immunoglobulin light chain combinations that can be produced by recombination of different genes in the germ line DNA. |
| (2) | The number of possible different immunoglobulin heavy chain combinations that can be produced by recombination of different genes in the germ line DNA. | ||
| A | 11. | (1) | The communicability of a disease to which 20% of the affected population is immune. |
| (2) | The communicability of a disease to which 50% of the affected population is immune. | ||
| B | 12. | (1) | The probability that an extracellular organism would produce a chronic disease. |
| (2) | The probability that an intracellular organism would produce a chronic disease. | ||
| A | 13. | (1) | The number of structural domains in the alpha chain of a Class I MHC molecule. |
| (2) | The number of structural domains in the alpha chain of a Class II MHC molecule. | ||
| A | 14. | (1) | The amount of precipitate formed when an antigen-antibody ratio is close to 1:1. |
| (2) | The amount of precipitate formed when an antigen-antibody ratio is close to 1:10. | ||
| A | 15. | (1) | The ability of Factor I to inhibit the activation of the complement cascade by cleaving cell membrane bound C3b. |
| (2) | The ability of Protein H to inhibit the activation of the complement cascade by cleaving cell membrane bound C3b. | ||
| A | 16. | (1) | The probability that the idiotypic network hypothesis for regulation of the humoral response occurs when antibody levels are relatively high. |
| (2) | The probability that the idiotypic network hypothesis for regulation of the humoral response occurs when antibody levels are relatively low. | ||
| B | 17. | (1) | The role of lipopolysaccharide (LPS) in activation of the complement cascade via the classical pathway. |
| (2) | The role of lipopolysaccharide (LPS) in activation of the complement cascade via the alternate pathway. | ||
| B | 18. | (1) | The year that Benjamin Martin described his germ theory of disease. |
| (2) | The year that Robert Koch described his postulates. | ||
| B | 19. | (1) | The time required to observe a reaction resulting from a Type I hypersensitivity. |
| (2) | The time required to observe a reaction resulting from a Type IV hypersensitivity. | ||
| A | 20. | (1) | The virulence of an organism with an LD50 of 5 x 103. |
| (2) | The virulence of an organism with an LD50 of 5 x 107. | ||
| A | 21. | (1) | The similarities between a T-cell receptor molecule and the antigen binding domain fragment of IgG. |
| (2) | The similarities between a T-cell receptor molecule and the receptor binding domain (Fc) fragment of IgG. | ||
| B | 22. | (1) | The role of the thyroid in the maturation of T-cells. |
| (2) | The role of the thymus in the maturation of T-cells. | ||
| A | 23. | (1) | The immunogenicity of a typical exotoxin. |
| (2) | The immunogenicity of a typical endotoxin. | ||
| B | 24. | (1) | The role of cytotoxic T-cells in the process known as antibody-dependent cell-mediated cytotoxicity. |
| (2) | The role of K-cells in the process known as antibody-dependent cell-mediated cytotoxicity. | ||
| C | 25. | (1) | The association between a Type II hypersensitivity and the disease known as autoimmune hemolytic anemia. |
| (2) | The association between a Type II hypersensitivity and the disease known as pemphigus. |
Questions 31-34: Correctly match the IMMUNOGLOBULIN on the left with its appropriate CHARACTERISTIC(S) listed on the right. | |||||
| G | 31. | IgD | A. | Found in secretions | |
| D | 32. | IgG | B. | Has 10 antigen binding sites | |
| A | 33. | IgA | C. | Responsible for allergies | |
| F | 34. | IgM | D. | Binds complement | |
| E. | Both A and C | ||||
| F. | Both B and D | ||||
| G. | None of the above | ||||
Questions 26-30: Correctly match the MOLECULE on the left with its appropriate CELL TYPE(S) listed on the right. | |||||
| C | 26. | Complement component C3b receptor | A. | B-cells | |
| F | 27. | Class II MHC | B. | T-cells | |
| A | 28. | Surface Immunoglobulin | C. | Macrophages | |
| F | 29. | Immunoglobulin Fc Receptor | D. | B-cells AND T-cells | |
| B | 30. | T-cell Receptor | E. | T-cells AND Macrophages | |
| F. | B-cells AND Macrophages | ||||
| G. | T-cells AND B-cells AND Macrophages | ||||
| H. | None of the above | ||||
Questions 35-38: Correctly match the COMPLEMENT COMPONENT listed on the left with its appropriate FUNCTION(S) listed on the right. | |||||
| D | 35. | Factor B | A. | Polymerizes to form MAC | |
| B | 36. | C5a | B. | Chemotactic factor | |
| G | 37. | C1s | C. | Antibody recognition protein | |
| A | 38. | C9 | D. | Combines with C3b | |
| E. | Both A and B | ||||
| F. | Both C and D | ||||
| G. | None of the above | ||||
39. List three (3) of the four characteristics that define an antigenic substance (3 points).
| 1) large molecular weight, 2) complex structure, |
| 3) accessible to the immune system, 4) foreign (not "self") |
40. (2 points) Give the equation that describes the affinity constant for an antibody-antigen interaction.
| [Ab-Ag complex] | |
| Affinity K = | ---------------------- |
| [Ab] x [Ag] |
41. (2 points) Exactly what molecule does the structure to the right represent?
Answer: Class II MHC
42. (2 points) A laboratory technician was given a sample of blood from a patient suspected of having a viral infection and asked to test for the presence of anti-viral antibody. The technician used a complement fixation assay for this determination. Describe what end result the technician would observe if the patient's serum did not contain anti-viral antibody.
Answer: The end result would be the lysis of the sheep red blood cells with a change in the color of the solution to pink or red.
43. (5 points) Draw the general structure of an IgG immunoglobulin showing i) the correct number of polypeptide chains, ii) the Fc region, iii) the antigen binding region, iv) the constant regions and v) the variable regions.
44. (6 points) A researcher studying several new bacterial exotoxins performed the following experiment. A number of mice were divided into 2 groups. The first set of mice were given six different doses of Toxin A and the second group of mice were given six different doses of Toxin B. After 24 hours, the percentage of dead mice was determined and the results are shown in the table.
| Dose of Toxin (arbitrary units) | ||||||
| 0 | 1 | 2 | 3 | 4 | 5 | |
| Toxin A | 0 % | 20 % | 65 % | 85 % | 100 % | 100 % |
| Toxin B | 0 % | 3 % | 10 % | 50 % | 90 % | 100 % |
Use these data to 1) draw a graph, 2) determine the LD50 for the two treatments and 3) indicate which of the two treatments had the greatest virulence.
| Treatment | LD50 |
| Toxin A | 1.6 |
| Toxin B | 3.0 |
Greatest virulence: Toxin A
45. (4 points) A researcher studying a particular antigen-antibody reaction performed the following experiment. First, five (5) ml of serum containing the antibody was added to each of five different tubes. Then, different amounts of the antigen was added to each tube. After centrifugation, the amount of Ag-Ab precipitate was measured and the results are shown in the table.
| Amount of Antigen (arbitrary units) | 1 | 2 | 3 | 4 | 5 |
| Weight of Precipitate | 2 mg | 4 mg | 8 mg | 4 mg | 2 mg |
Use these data to draw a graph. On the graph, indicate the regions of 1) antibody excess, 2) antigen excess and 3) equivalence.
