34. There is reciprocal regulation of glycolytic and gluconeogenic reactions interconverting fructose-6-phosphate and fructose-1,6-bisphosphate. Which one of the following statements about this regulation is   not   correct?
(A) Fructose-2,6-bisphosphate activates phosphofructokinase-1.
(B) Fructose-2,6-bisphosphate inhibits fructose-1,6-bisphosphatase.
(C) The fructose-1,6-bisphosphatase reaction is exergonic.
(D) The phosphofructokinase-1 reaction is endergonic.
(E) This regulation allows control of the direction of net metabolite flow through the pathway.

30. Recent studies have shown that the H-bond between the distal histidine and oxygen molecule in myoglobin has a strength of ~15 kJ/mol, but in hemoglobin, the strength of the bond is only ~8 kJ/mol. What does this suggest about the differences between myoglobin and hemoglobin? (A) Myoglobin binds oxygen more strongly than hemoglobin. (B) Hemoglobin binds oxygen more strongly than myoglobin. (C) The iron in myoglobin is more easily oxidized than in hemoglobin. (D) The iron in hemoglobin is more easily oxidized than in myoglobin. (E) None of the above.

31. Which of the following is true regarding effectors of oxygen-hemoglobin binding? (A) Actively metabolizing tissues produce acid which increases hemoglobin's affinity for oxygen. (B) The presence of CO2 enhances the release of oxygen from hemoglobin. (C) 2,3-Bisphosphoglycerate must dissociate from hemoglobin before oxygen can be released. (D) The presence of protons will counter the effect of CO2 on the release of oxygen by hemoglobin. (E) None of the above.

32. Which of the following statements 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 are true.

33. Which of the following is correct concerning the mitochondrial ATP synthase? (A) It can synthesize ATP after it is extracted from broken mitochondria. (B) It catalyzes the formation of ATP even though the reaction has a large positive . (C) It consists of F₀ and F₁ subunits, which are transmembrane (integral) polypeptides. (D) When it catalyzes the ATP synthesis reaction, the  is actually close to zero. (E) It is actually an ATPase and only catalyzes the hydrolysis of ATP.

35. Gluconeogenesis must use "bypass reactions" to circumvent(規避、繞行) three reactions in the glycolytic pathway that are highly exergonic and essentially irreversible. Reactions carried out by which three of the enzymes listed must be bypassed in the gluconeogenic pathway? 1. Hexokinase 2. Phosphoglycerate kinase 3. Phosphofructokinase-14. Pyruvate kinase 5. Triosephosphate isomerase (A) 1, 2, and 4. (B) 1, 2, and 3. (C) 1, 3, and 4. (D) 1, 4, and 5. (E) 2, 3, and 4.

36. The reaction of the citric acid cycle that is most similar to the pyruvate dehydrogenase complex-catalyzed conversion of pyruvate to acetyl-CoA is the conversion of: (A) citrate to isocitrate. (B) fumarate to malate. (C) malate to oxaloacetate. (D) succinyl-CoA to succinate. (E) α-ketoglutarate to succinyl-CoA.

37. Which of these statements about the membrane proteins is   true  ? (A) An integral membrane protein can be extracted with a chelating agent that removes divalent cations. (B) Peripheral membrane proteins are generally noncovalently bound to membrane lipids. (C) Carbohydrate moieties of membrane glycoproteins are linked to the intracellular domain of the proteins. (D) Peripheral membrane proteins may have functional units on both sides of the membrane. (E) Glycosylphosphatidylinositols, abbreviated GPI, are complex glycolipids that attach some proteins to the cytosolic surface of the plasma membrane.

38. In amino acid catabolism, the first reaction for many amino acids is a(n): (A) oxidative deamination requiring . (B) hydroxylation requiring NADPH and O2. (C) transamination requiring pyridoxal phosphate (PLP). (D) reduction requiring pyridoxal phosphate (PLP). (E) decarboxylation requiring thiamine pyrophosphate (TPP).

39. Which of the following is   not   true about cyclic electron flow of photophosphorylation? (A) Cyclic electron flow produces more NADPH per photon than noncyclic electron flow. (B) Cyclic electron flow involves only photosystem I. (C) Plastocyanin is required for cyclic electron flow. (D) Cyclic electron flow leads to the build-up of a proton gradient. (E) Cyclic electron flow does not produce O2.

40. Which of the following statements about mitochondrial transport systems is correct? (A) Malate-aspartate shuttle: converts cytosolic NADH to mitochondrial FADH2. (B) ATP-ADP translocase: transfers ATP and a proton from matrix to cytosol while transferring ADP from cytosol to matrix. (C) Glycerophosphate shuttle: converts cytosolic FADH2 to mitochondrial NADH. (D) The malate-aspartate shuttle is irreversible while the glycerophosphate shuttle is reversible. (E) None of the above are correct.