Question

Which one of the following statements about gluconeogenesis is false? A. For starting materials, it can use carbon skeletons derived from certain amino acids. B. It consists entirely of the reactions of glycolysis, operating in the reverse direction. C. It employs the enzyme glucose 6-phosphatase. D. It is one of the ways that mammals maintain normal blood glucose levels between meals. E. It requires metabolic energy (ATP or GTP). The steps of glycolysis between glyceraldehyde 3-phosphate and 3-phosphoglycerate involve all of the following except: A. ATP synthesis. B. catalysis by phosphoglycerate kinase. C. oxidation of NADH to NAD^+. D. the formation of 1.3-bisphosphoglycerate. E. utilization of Pi. When the linear form of glucose cyclizes, the product is a(n): A. anhydride. B. glycoside. C. hemiacetal. D. lactone. E. oligosaccharide.

Answer 1

Ans 10: Correct answer is Option B: It consists entirely of the reactions of glycolysis, operating in the reverse direction.

Explanation:

Gluconeogenesis involves synthesis of glucose from non-carbohydrate precursors such as pyruvate, lactic acid, certain amino acids like alanine, glutamine. It is one of the ways to maintain normal glucose levels in mammals. Gluconeogenesis uses enzymes such as glucose-6-phosphate and molecules like ATP.

On the other hand glycolysis involves metabolizing molecule of glucose into smaller molecules. However, gluconeogenesis and glycolysis are not simply reverse of each other. There are many irreversible steps in glycolysis, which are not observed in gluconeogenesis.

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Ans 11: Correct answer is Option C: Oxidation of NADH to NAD+

Explanation:

Conversion of glyceraldehyde-3-phosphate to 3-phosphoglycerate involves reduction of NAD+ to NADH and not the reverse.

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Ans 12: Correct answer is Option C: Hemiacetal

Explanation:

Linear form of glucose cyclizes by reaction of aldehyde group and hydroxyl group to give hemiacetal. Hence, cyclic form of glucose is called as hemiacetal.