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.

24._______and_______ are produced in the light reactions of photosynthesis which are used to convert _______to_______. (A) ATP； NADPH； carbon dioxide； sugar. (B) oxygen； ATP； NADPH； carbon dioxide (C) ATP； NADPt； carbon dioxide； sugar (D) oxygen； NADPH； ATP； sugar (E) NADPH； ATP； sugar； carbon dioxide

25. 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.

26. Given a Hill plot for protein X (shown in the figure). What is protein X's Hill coefficient? (A)0.5 (B)1 (C)2 (D) 3 (E) 4

27. What amino acids utilize chorismate for their biosynthetic ingredient? (A) Trp, Asp, Phe (B) Thr, Asn, Lys (C) Asp, Thr, Gln (D) Trp, Tyr, Phe (E) Met, Ile, Leu, Lys

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

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.

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