35. Which of the following statements about the oxidative decarboxylation of pyruvate in aerobic conditions in animal cells is   correct  ?
(A) The process occurs in the cytosolic compartment of the cell.
(B) The methyl group is eliminated as CO₂.
(C) One of the products of the reactions of the pyruvate dehydrogenase complex is a thioester of acetate.
(D) The pyruvate dehydrogenase complex uses all of the following as cofactors: , lipoic acid, pyridoxal phosphate (PLP), and FAD.
(E) The reaction is so important to energy production that pyruvate dehydrogenase operates at full speed under all conditions.

31. The T form (tense or taut form) of deoxyhemoglobin differs from oxyhemoglobin (the R form or relaxed form) by all   except  : (A) covalent linkages between subunits. (B) specific intrachain hydrogen bonds. (C) between β-subunit salt links (ion-pair bonds). (D) between a-subunits salt links (ion-pair bonds). (E) intrachain salt bridges.

32. The power stroke in muscle contraction is associated with: (A) the binding of ATP to ATPase. (B) the hydrolysis of ATP. (C) binding of myosin to actin. (D) addition of water for ATP hydrolysis. (E) the dissociation of ADP and Pi from the ATPase.

33. Which of the following four statements regarding glycolysis and gluconeogenesis is   correct  ? (1) Substrate-level phosphorylation occurs when conversion of1,3-bisphosphoglycerate to 3-phosphoglycerate occurs. (2) The only oxidative reaction in glycolysis is the conversion of glyceraldehyde-3-phosphate to 1,3-bisphosphoglycerate. (3) The phosphofructokinase-1 catalyzes the glycolytic reaction step that is irreversible in gluconeogenesis. (4) If fructose-2,6-bisphosphate is low, glycolysis proceeds； if fructose-2,6-bisphosphate is high, gluconeogenesis proceeds. (A) (1), (2), and (4) are correct. (B) (1), (3), and (4) are correct. (C) (1), (2), and (3) are correct. (D) (2), (3), and (4) are correct. (E) All are correct.

34. Consider the reaction below, which of the following statement is   false  ? (A) When M is acetaldehyde, enzyme 1 is pyruvate decarboxylase. (B) When M is oxaloacetate, enzyme 1 is pyruvate carboxylase. (C) When M is phosphoenopyruvate, enzyme 2 is pyruvate kinase. (D) When M is malate, enzyme 2 is malic enzyme. (E) None of above is false.

36. 2,4-dinitrophenol and oligomycin inhibit mitochondrial oxidative phosphorylation. 2,4-dinitrophenol is an uncoupling agent； oligomycin blocks the ATP synthesis reaction itself. Therefore,2,4-dinitrophenol will: (A) allow electron transfer in the presence of oligomycin. (B) allow oxidative phosphorylation in the presence of oligomycin. (C) block electron transfer in the presence of oligomycin. (D) diminish O2 consumption in the presence of oligomycin. (E) do none of the above.

37. Which one   directly   regulates fatty acid breakdown? (A) Succinyl CoA. (B) Myristoyl CoA. (C) Acetyl CoA. (D) Malonyl CoA. (E) Fatty acid synthase.

38. Which one is   not   the limiting step in lipid metabolism? (A) Fatty acyl CoA + Carnitine → Fatty acyl carnitine (B) Palmitoyl CoA + Serine → Sphinganine (C) Acetyl CoA → Malonyl CoA (D) HMG COA → Mevalonate (E) Mevalonate → Cholesterol

39. If an ATP synthase contains 12 c subunits, 3 a subunits and 3 ẞ subunits, how many protons must pass through this complex for every ATP molecule synthesized and transported to the cytosol, assuming that each ATP synthesized requires one proton for transport to the cytosol. (A) 3. (B) 4. (C) 5. (D) 12. (E) 13.

40. It is crucial that regulation occur at pyruvate dehydrogenase because: (A) pyruvate kinase is reversible. (B) lactate dehydrogenase is the only other enzyme to use pyruvate. (C) the product acetyl-CoA is committed to oxidation in the citric acid cycle or fatty acid biosynthesis. (D) alanine aminotransferase would use the pyruvate. (E) All of the above.

41. An essential feature of the glyoxylate cycle, which is not associated with the TCA cycle is: (A) it utilizes condensation of acetyl-CoA with glyoxylate. (B) each complete cycle produces a net gain of two 4-carbon molecules. (C) it occurs in chloroplasts and the mitochondria of plant seeds. (D) mammals use the glyoxylate cycle for gluconeogenesis. (E) it is a reductive pathway that utilizes NADPH as an electron source.