32.Which of the following statement(s) is incorrect regarding the formation of ketone body?
(A) Acetoacetate and D-β-hydroxybutyrate are transported by the blood to tissues such as brain and muscle other than the liver.
(B) Ketone bodies are formed in the liver through the condensation of acety1-CoA, which is an unfavorable reaction that needs excess of substrates.
(C) Starvation and untreated diabetes mellitus lead to overproduction of ketone bodies in the liver, with several adverse effects on health.
(D) Ketone bodies are used as fuels in all tissues except liver, which lacks-ketoacyl-CoA transferase for the reaction to activate acetoacetate.
(E) )All above are correct.

複選題28. Regarding the binding energy generated from enzyme-substrate interactions, which statement is accurate? (A) It is insufficient to account for the substantial rate increases caused by enzymes. (B) It may be utilized to maintain two substrates in the ideal orientation for a reaction. (C) It originates from the formation of covalent bonds between the enzyme and substrate. (D) A large portion of it comes from covalent bonds between the enzyme and substrate. (E) The majority of it is expended in just attaching the substrate to the enzyme.

29.Which of the following is not involved in signal transduction by the B-adrenergic rece (A) Cyclic AMP synthesis (B) GTP hydrolysis (C) GTP-binding protein (D) Protein kinase (E) All of the above are involved.

30. Regulation of cholesterol biosynthesis:(A) involves transcriptional regulation but not covalent regulation. (B) is sensitive to insulin but not glucagon. (C) occurs in the short term primarily by regulating HMG-CoA reductase. (D) involves changes in the rate of biosynthesis of critical enzymes, but not changes in the rate of proteolysis of those enzymes. (E) All above are correct.

31. A marathon runner is engaged in a 20-mile run. During a 20-mile run, there is an increase in the rate at which acyl-CoA is taken up by the mitochondria and used by β-oxidation. Part of the increase can be explained by the increase fatty acid entering the cell and part is explained by all of the following except (A) Glucagon triggers the release of free fatty acids from adipose tissue to meet energy needs. (B) AMP-dependent protein kinase (AMPK) causes the phosphorylation of acetyl-CoA carboxylase. (C) Phosphorylation of acetyl-CoA carboxylase inhibits the production of malonyl-CoA. (D) The malonyl-CoA concentration drops and inhibition of carnitine-acyltransferase II is removed. (E) Much more acyl-carnitine is available to use the carnitine/acyl-carnitine transporter

33. Which is a difference between integral membrane proteins and peripheral membrane proteins? (A) Integral membrane proteins contain mainly a-helices while peripheral membrane proteins contain mainly B-sheets. (B) Integral membrane proteins often contain carbohydrates on the inner surface while peripheral membrane proteins often contain carbohydrates on the outer surface. (C) Integral membrane proteins bind to the membrane using hydrophobic forces while peripheral membrane proteins bind to the membrane using hydrophilic forces. (D) Integral membrane proteins always span the entire membrane one time while peripheral membrane proteins are always located on one side of the membrane. (E) Integral and peripheral membrane proteins both contain transmembrane domain so they could associate with membranes.

34. Which of the following represents the correct sequence of events in a cycle of β-oxidation beginning with a saturated fatty acyl-CoA? (A) hydration, FAD-coupled oxidation, NAD+-coupled oxidation, thiolytic cleavage (B) FAD-coupled oxidation, hydration, NAD+-coupled oxidation, thiolytic cleavage (C) FAD-coupled oxidation, NAD+-coupled oxidation, hydration, thiolytic cleavage (D) NAD+-coupled oxidation, FAD-coupled oxidation, hydration, thiolytic cleavage (E) NAD+-coupled oxidation, hydration, FAD-coupled oxidation, thiolytic cleavage

35. The C4 pathway for carbon dioxide fixation has what requirement compared to the C3 pathway? (A) require less CO2 (B) require more CO2 (C) require less NADPH (D) require less ATP (E) require more ATP

36. Which of the following statements about the oxidative decarboxylation of pyruvate in aerobic conditions in animal cells is false? (A) The process occurs in mitochondria. (B) The carboxyl 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: NAD+, lipoic acid, pyridoxal phosphate (PLP), and FAD. (E) The reaction is so important to energy production that pyruvate dehydrogenase is tightly regulated.

37. Which of the following statements about the citric acid (CA) cycle is correct? 1. The citric acid cycle is considered part of aerobic metabolism because the NADH and FADH2 produced are reoxidized in the electron transport chain linked to oxygen. 2. Succinyl CoA is a high-energy compound in CA cycle that can provide energy for phosphorylation of ADP at the substrate level. 3. Two enzymes, pyruvate carboxylase and pyruvate dehydrogenase, outside the cycle can profoundly affect CA cycle activity. (B) 2 and 3. (C) 1 and 3. (E) None of above is correct. (A) 1 and 2. (D) 1,2 and 3.

38. A poison that prevents the transfer of electrons from the last iron-sulfur cluster of Complex I to coenzyme Q is added to a suspension of actively respiring mitochondria. Which statement best describes the cffect seen? (A) ATP production would be reduced as fewer protons would be pumped out of the mitochondrial matrix. (B) ATP production would be severely impaired as this would completely block electron transport through the electron transport chain. (C) ATP production would be impaired as this would uncouple oxidative phosphorylation from electron transport. (D) This compound would have little to no effect on ATP production. (E) None of above is correct.