| 21. | Which of the modification in hemoglobin is the cause of sickle cell anemia? |
| a. | A mutation in the beta chain |
| b. | A deletion in the beta chain |
| c. | Replacement of the B chain by D chain |
| d. | None of the above |
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Answer: (a).A mutation in the beta chain
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| 22. | Klinefelter syndrome is a manifestation of which chromosome aneuploidy? |
| a. | XXX |
| b. | XYY |
| c. | XXY |
| d. | None of these |
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Answer: (c).XXY
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| 23. | During sickle cell anemia which of the following takes place? |
| a. | Glutamine change to valine |
| b. | Valine change to glutamine |
| c. | Aspartic acid change to glutamic acid |
| d. | Glutamic acid change to aspartic acid |
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Answer: (a).Glutamine change to valine
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| 24. | Methotrexate is toxic to human cells because it inhibits |
| a. | formation of CTP from UTP |
| b. | reduction of H2 folate to H4 folate |
| c. | synthesis of PRPP |
| d. | none of the above |
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Answer: (b).reduction of H2 folate to H4 folate
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| 25. | What is the defective enzyme in the glycogen storage Von Gierke's disease? |
| a. | Phosphorylase |
| b. | Phosphofructokinase |
| c. | Glucose-6-phosphatase |
| d. | None of the above |
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Answer: (c).Glucose-6-phosphatase
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