E-PolyLearning

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

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

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

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

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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