35. Which of the following statements regarding the enzymes involving in citric acid cycle is false?

 1. Citrate synthase is inhibited by NADH and succinyl-CoA.

 2. Isocitrate dehydrogenase requires TPP, lipoic acid, FAD, and NAD⁺ as cofactors. 

 3. α-ketoglutarate dehydrogenase is activated by ADP and NAD⁺. 

 4. Reactions catalyzed by Succinate dehydrogenase can be blocked by malonate.

 5. The reaction catalyzed by fumarase is a dehydration reaction.
(A) 1 and 3 are false.
(B) 2 and 5 are false.
(C) 1 and 4 are false.
(D) 2 and 3 are false.
(E) 4 and 5 are false.

31. Which of the following statement regarding enzyme regulation is true? (A) Addition of an inhibitor to a V system results in kinetics similar to addition of a competitive inhibitor to a typical hyperbolic system. (B) Allosteric effectors are always more powerful than covalent modification. (C) Addition of an allosteric activator to a K system changes the plot of V vs. [S] from a sigmoidal curve to a more hyperbolic curve. (D) The T state of an enzyme generally has more activity than the R state. (E) None of the above is true.

32. When a mixture of glucose 6-phosphate and fructose 6-phosphate is incubated with the enzyme phosphohexose isomerase, the final mixture contains twice as much glucose 6-phosphate as fructose 6-phosphate. Which one of the following statements is most nearly correct, when applied to the reaction below? (R = 8.315 J/mol‧ K and T = 298 K)? (A) is -1.7 kJhmol. (B)  is +1.7 kJ/mol. (C) is incalculably large and positive. (D)  is incalculably large and negative. (E) is zero.

33. Which of the following statement regarding citric acid cycle is false? (A) Citric acid cycle is amphibolic because it plays a role in both catabolism and anabolism. (B) The immediate electron acceptor for the majority of the oxidative reactions of the citric acid cycle is NAD+. (C) Many intermediates of citric acid cycle are starting points for synthesis of a variety of compounds (D) Animals can use fat or acetate as the carbon source because they can replenish citic acid cycle intermediates by anaplerotic reaction. (E) All of above are false.

34. Which of the following four statements regarding glycolysis and gluconeogenesis is correct?  1. The conversion of 1 mole of frctose 1,6-bisphosphate to 2 mole of pyruvate by the glycolytic pathway results in a net formation of 2 mole of NAD+ and 4 mole of ATP.  2. The step of glycolysis between glyceraldehyde 3-phosphate and 3-phosphoglycerate involves oxidation of NADH to NAD+.  3.Acetate cannot serve as the starting material for the synthesis of glucose via gluconeogenesis in animals.  4. Pyruvate kinase is used in both glycolysis and gluconeogenesis.  5.The oxidation of 3 mole of glucose by the pentose phosphate pathway may result in the production of 3 mole of pentose, 4 mole of NADPH, and 3 mole of CO2. (A)1 and 2 are correct. (B) 3 and 4 are correct. (C) 3 is correct. (D) 4 is correct. (E) All are correct.

36. Which statement about ATP synthesis in mitochondria is false? (A) To form proton gradient for ATP synthesis in mitochondria requires various proteins that serve as electron carriers to be oriented asymmetrically with respect to the two sides of the inner mitochondrial membrane. (B) The proton gradient that is generated by electron transfer reactions is used to induce a conformational change in the ATP synthase. (C) Evidence for chemiosmotic coupling as the mechanism for ATP synthesis is based on the observation that many different kinds of substances can serve as uncouplers. (D) The Fo part of the ATP synthase serves as a proton channel, and the F part of the ATP synthase is the site of ATP formation. (E) None of above is false.

37. Seven of the ten reactions of glycolysis are reversible (△G near zero) and can be used in reverse of glycolysis for gluconeogenesis. The three irreversible reactions are catalyzed by: (A) hexokinase, phosphoglycerate kinase, and pyruvate kinase. (B) triose phosphate isomerase, phosphoglycerate mutase, and pyruvate kinase. (C) enolase, phosphoglycerate kinase, and phosphofructokinase-1. (D) hexokinase, phosphoglucoisomerase, and glyceraldehyde-3-phosphate dehydrogenase. (E) hexokinase, phosphofructokinase-1, and pyruvate kinase.

38. Addition of water across a double bond, or removal of water to form a double bond, is catalyzed by a suboclass of the lyase class of enzymes. Which of the following glycolytic enzymes would be a lyase? (A) Glyceraldehyde-3-phosphate dehydrogenase (B) Triose phosphate isomerase (C) Phosphoglycerate mutase (D) Hexokinase (E) Enolase

39. If levels of___________ and/or_____________are low， pyruvate is directed primarily  into _________； pyruvate is converted into_______for gluconeogenesis.(A) NADH; ATP; glycolysis; oxaloacetate (C) ATP; acetyl-COA; TCA cycle; oxaloacetate (B) ATP; NADPH; glycolysis; acetyl-CoA (D) NAD+; acetyl-CoA; TCA cycle; acetyl-CoA (E) ATP; acetyl-CoA; glycolysis; malate

40. The 6-phosphogluconate dehy drogenase reaction in the pentose phosphate pathway is an example of________ and results in the production of_________. (A) substrate-level phosphorylation; ATP (B) oxidative-decarboxylation; NADPH (C) TPP-assisted decarboxylation; NADH (D) phosphate addition; ADP (E) None of the above.

41. When a cell with the pentose phosphate pathway has need for more pentose phosphates, but not for additional NADPH: (A) glucose-6-phosphate dehydrogenase is activated. (B) the oxidative and non-oxidative enzymes of the pentose phosphate pathway are active. (C) the non-oxidative enzymes produce pentose phosphates from fructose-6-phosphate and glyceraldehyde-3-phosphate. (D) all enzymes of glycolysis and pentose phosphate pathway are active. (E) None are true.