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

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.

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

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.

42.In the Southern hybridization procedure, the gel after electrophoresis is treated with NaOH and before blotting. What is the primary function of the alkaline treatment? (A) It neutralizes any acid soluble impurities in the gel. (B) It cleaves the DNA into smaller fragments to permit greater efficiency of transfer. (C) It inactivates any restriction endonucleases that may be in the gel.. (D) It neutralizes any acidic phosphate groups that might prevent hybridization. (E) It denatures the duplex DNA to single-stranded DNA (ssDNA).

43. A characteristic of the glycerophosphate shuttle is: (A) It shuttles NADH across the mitochondrial membrane to yield 2.5 ATP/ADH. (B) It shuttles "NADH electron equivalents" across the mitochondrial membrane to yield 1.5 ATPNADH. (C) It only operates efficiently when the [NADH] in the cytoplasm is higher than in the matrix. (D) Malate is a key component in the shuttle process. (E) Aspartate is a key component in the shuttle process.

44. Oxaloacetate uniformly labeled with14C (ie., with equal amounts of14C in cach of its carbon atoms) is condensed with unlabeled acetyl-CoA. After a single pass through the citric acid cycle back to oxaloacetate, what fraction of the original radioactivity will be found in the oxaloacetate? (A) All (B) 1/2 (C) 1/3 (D) 1/4 (E) 3/4

45. The oxidation of a particular hydroxy substrate to a keto product by mitochondria has a P/O ratio of less than 2. The initial oxidation step is very likely directly coupled to the: (A) oxidation of a flavoprotein. (B) oxidation of a pyridine nucleotide. (C) reduction of a flavoprotein. (D) reduction of a pyridine nucleotide. (E) reduction of cytochrome as.