40. Which of the following enzymes catalyzes the conversion shown below in the glycolysis pathway?
(A) Hexokinase
(B) Phosphofructokinase-1 (PFK-1)
(C) Phosphohexose isomerase
(D)Phosphoglucose mutase
(E) Phosphohexose epimerase

36. Which of the following statements about urea cycle is correct? 1. The urea cycle is linked to the citric acid cycle by arginine. 2. Aspartic acid is the main amino acid precursor for the carbon chain in arginine.  3. Citrulline is synthesized in the cytosol and transported to the mitochondrial matrix for subsequent reaction.  4. Ornithine is synthesized in the mitochondrial matrix and transported to the cytosol for subsequent reaction. (A) All of above are incorrect. (B) 1 and 3 are correct. (C) 2 and 4 are correct. (D) 1 and 2 are correct. (E) 3 and 4 are correct.

37. Shown is the purine catabolism. What is the chemical structure of the compound ( A )?(A)① (B)② (C)③ (D) ④(E)⑤

38. How many ATPs are produced by the complete metabolization of the saturated fatty acid shown below? (D) 50 (A) 32 (B) 36 (C) 38 (E) 52

39. ne pyrophosphate (TPP), derived from vitamin B1, is a coenzyme of pyruvate decarboxylase. Regar the functional role of TPp, which atom will be converted into a nucleophile? (A) No. 1. (B) No. 2. (C) No. 3. (D) No. 4. (E) No. 5.

41. The reaction, 1,3-bisphosphoglycerate→ 2,3-bisphosphoglycerate, is catalyzed by: (A) bisphosphoglycerate phosphatase (B) bisphosphoglycerate mutase (C) 2,3-bisphosphoglycerate synthetases (D) 3-phosphoglycerate isomerase (E) 1,3-bisphosphoglycerate hydrolase

42. All are uses of glucose-6-phosphate in liver except: (A) catabolized to acetyl-CoA for fatty acid biosynthesis. (B) generate NADPH and pentoses. (C) released as glucose to blood stream. (D) converted to glycogen. (E) All are true.

43. In the citric acid cycle, succinate is dehydrogenated by succinate dehydrogenase, which yields fumarate. The dehydrogenation of two of the four hydrogens in succinate (labeled as H1~H4 in the figure shown below) is stereospecific, with the pro-S hydrogen removed from one carbon atom and the pro-R hydrogen removed from the other.  Which of the following two hydrogens could be abstracted in the four hydrogens of the succinate molecule in the reaction catalyzed by succinate dehydrogenase? a. H1 and H2 b. H1 and H3 c. H1 and H4 d. H2 and H3 e. H2 and H4 f. H3 and H4 (A) b and e (B) c and d (C) a and f (D) Only c could occur. (E) Only d could occur.

44. Which of the following substrates cannot contribute to net gluconeogenesis in mammalian liver? (A) Alanine (B) Glutamate (C) Palmitate  (D) Pyruvate(E) a-ketoglutarate

45. Glucose, labeled with in different carbon atoms, is added to a crude extract of a tissue rich in the enzymes of the pentose phosphate pathway. The most rapid production of will occur when the glucose is labeled in: (A) C-1. (B) C-3. (C) C-4. (D) C-5. (E) C-6.

46. Which of these statements is true? (A) Integral membrane proteins usually contain one or more regions with a high hydropathy index. (B) In integral membrane proteins, the domains that protrude on the cytoplasmic face of the plasma membrane nearly always have covalently attached oligosaccharides. (C) A hydropathy plot is used to extrapolate for the true molecular weight of a membrane protein. (D) A hydropathy plot is used to deduce the quaternary structure of a membrane protein. (E) A hydropathy plot is used to determine the water-solubility of a protein.