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Select the one best response to each question!
Which of the following statements accurately describes competitive binding assays?
| 1. Which of the following statements accurately describes competitive binding assays? a. Excess binding sites for the analyte are provided. b. Labeled and unlabeled analyte are present in equal amounts. c. The concentration of patient analyte is inversely proportional to bound radioactive label. d. All the patient analyte is bound in the reaction. |
| 2. How do heterogeneous assays differ from homogeneous assays? a. Heterogeneous assays require a separation step. b. Heterogeneous assays are easier to perform than homogeneous assays. c. The concentration of patient analyte is directly proportional to bound label in homogeneous assays. d. Homogeneous assays are more sensitive than heterogeneous ones. |
| 3. In the following equation, what is the ratio of bound radioactive antigen (Ag*) to bound patient antigen (Ag) 12Ag * 4Ag 4Ab → :___Ag * Ab ___AgAb Ag* ___Ag a. 1:4 b. 1:3 c. 3:1 d. 8:4 |
| 4. Which of the following characterizes a capture or sandwich enzyme assay? a. Less sensitive than competitive enzyme assays b. Requires two wash steps c. Best for small antigens with a single determinant d. A limited number of antibody sites on solid phase |
| 5. Advantages of EIA over RIA include all except which one of the following? a. Decrease in hazardous waste b. Shorter shelf life of kit c. No need for expensive equipment d. Ease of adaptation to automated techniques |
| 6. Which of the following is characteristic of direct fluorescent assays? a. The anti-immunoglobulin has the fluorescent tag. b. Antibody is attached to a solid phase. c. Microbial antigens can be rapidly identified by this method. d. The amount of color is in inverse proportion to the amount of antigen present. |
| 7. Which of the following is true of fluorescence polarization immunoassay? a. Both antigen and antibody are labeled. b. Large molecules polarize more light than smaller molecules. c. When binding occurs, there is quenching of the fluorescent tag. d. The amount of fluorescence is directly proportional to concentration of the analyte. |
| 8. All of the following are desirable characteristics of antibodies used in immunoassays except a. high affinity. b. high specificity. c. high cross-reactivity. d. not found in the patient sample. |
| 9. In a noncompetitive enzyme immunoassay, if a negative control shows the presence of color, which of the following might be a possible explanation? a. No reagent was added. b. Washing steps were incomplete. c. The enzyme was inactivated. d. No substrate was present. |
| 10. Which of the following best characterizes chemiluminescent assays? a. Only the antigen can be labeled. b. Tests can be read manually. c. These are only homogeneous assays. d. A chemical is oxidized to produce light. |
| 11. Immunofluorescent assays may be difficult to interpret for which reason? a. Autofluorescence of substances in serum b. Nonspecific binding to serum proteins c. Subjectivity in reading results d. Any of the above |
| 12. Which statement best describes flow-through immunoassays? a. Results are quantitative. b. Reagents must be added separately. c. They are difficult to interpret. d. They are designed for point-of-care testing. |
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