37. Which one of the following enzymatic activities would be decreased by thiamine deficiency?
(A) Fumarase.
(B) Isocitrate dehydrogenase.
(C) Malate dehydrogenase.
(D) Succinate dehydrogenase.
(E) α-Ketoglutarate dehydrogenase complex.

33. Which of these statements about enzyme-catalyzed reactions is   false  ? (A) At saturating levels of substrate, the rate of an enzyme-catalyzed reaction is proportional to the enzyme concentration. (B) If enough substrate is added, the normal Vmax of a reaction can be attained even in the presence of a competitive inhibitor. (C) The rate of a reaction decreases steadily with time as substrate is depleted. (D) The activation energy for the catalyzed reaction is the same as for the uncatalyzed reaction, but the equilibrium constant is more favorable in the enzyme-catalyzed reaction. (E) The Michaelis-Menten constant equals the [S] at which V = 1/2

34. When every enzyme molecule in the reaction mixture has its substrate-binding site occupied by substrate, the kinetics become _____ -order, and the velocity is _____. (A)(B) (C)(D) (E)

35. All are properties of regulatory enzymes   except  : (A) pathway end-products may act as allosteric inhibitors. (B) v vs [S] plots are sigmoid- or S-shaped. (C) monomeric enzymes with a single regulated active site. (D) substrate binding is cooperative. (E) may be stimulated by allosteric activators.

36. Which of the following cofactors is required for the conversion of succinate to fumarate in the citric acid cycle? (A) ATP. (B) Biotin. (C) (D) (E) FAD.

38. The conversion of 1 mole of fructose 1,6-bisphosphate to 2 mole of pyruvate by the glycolytic pathway results in a net formation of: (A) 1 mole of NADH and 1 mole of ATP. (B) 2 mole of NAD⁺ and 4 mole of ATP. (C) 1 mole of NAD⁺ and 2 mole of ATP. (D) 2 mole of NADH and 4 mole of ATP. (E) 2 mole of NADH and 2 mole of ATP.

39. Which one of the following statements is true? 1. In glycolysis, ATP is synthesized by both substrate-level and oxidative phosphorylation. 2. Fructose-1,6-bisphosphate is an allosteric factor for controlling by phosphofructokinase. 3. In the glyceraldehyde-3-phosphate dehydrogenase reaction, the amino acid cysteine is important in adding a second phosphate to glyceraldehyde phosphate. 4. During anaerobic metabolism in red blood cells, the carbons of glucose end up in lactic acid. 5. Phosphofructokinase and pyruvate kinase both are tetrameric. (A) All are true. (B) 1 and 4 are not true. (C) 5 is not true. (D) 1, 3 and 5 are not true. (E) 2 and 4 are not true.

40. Which one is incorrect regarding the rate limiting steps of lipid metabolism? (A) Carnitine acyltransferase I in β oxidation. (B) Acetyl-CoA carboxylase in fatty acid synthesis. (C) HMG reductase in phosphatidylcholine synthesis. (D) Phosphatidic acid phosphatase in phospholipid synthesis. (E) Serine palmitoyltransferase in sphingolipid synthesis.

41. Which one is incorrect regarding the intermediates and precursors in lipid metabolism? (A) Cis-Δ² enoyl CoA in β oxidation. (B) Mevalonate in cholesterol synthesis. (C) Phosphatidic acid in glycerolphospholipid synthesis. (D) Serine and palmitoyl-CoA in sphingolipid synthesis. (E) Δ³-Isopentenyl pyrophosphate is the precursor of vitamin A, E, K.

42. Which molecule contains an phosphoanhydride bond? (A) DNA. (B) RNA. (C) UMP. (D) ADP. (E) cAMP.

43. In the TCA cycle, carbon enters the cycle as ____ and exits as with metabolic energy captured as ____. (A) malonyl-CoA； water； NADH； [FADH2]； ATP (B) acetyl-CoA； CO2； ATP； NADH； [FADH2] (C) succinyl-CoA； CO2； ATP； NADH； NADPH (D) malonate； water； NADH； ATP； NADPH (E) acetyl-CoA； CO2； NADH； ATP； NADPH