18. When a mixture of glucose 6-phosphate and fructose 6-phosphate is incubated with the enzyme phosphohexose isomerase, the final mixture contains twice as much giucose 6-phosphate as fructose 6-phosphate. Which one of the following statements is most nearly correct, when applied to the reaction below? (R = 8.315 J/mol·K 且 T = 298 K) 

Glucose 6-phosphatefructose 6-phosphate
(A)  ΔG'° is +1.7 kJ/mol.
(B)  ΔG'° is -1.7 kJ/mol.
(C) ΔG'° is incalculably large and negative.
(D) ΔG'°is incalculably large and positive.
(E)  ΔG'° is zero.

14. 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.

15. The enzyme glycogen phosphorylase:(A) catalyzes a cleavage of β(1→4) bonds.(B) catalyzes a hydrolytic cleavage of α(1→4) bonds.(C) is a substrate for a kinase.(D) uses glucose 6-phosphate as a substrate.(E) uses glucose as a substrate.

16. All are characteristics associated with "brown fat" except:(A) high levels of mitochondria rich in cytochromes.(B) presence of uncoupler protein-1, thermogenin, in the mitochondrial inner membrane.(C) energy from oxidation is converted to heat.(D) found in newborns and hibernating animals.(E) All are characteristics.

17. From the abbreviated name of the compound Gal(β1→4)Glc, we know that:(A) C-4 of glucose is joined to C-1 of galactose by a glycosidic bond.(B) the compound is a D-enantiomer.(C) the galactose residue is at the reducing end.(D) the glucose is in its pyranose form.(E) the glucose residue is the β anomer.

19.If carbon I is the carbony1 group of an aldopentose, which carbon determines if the sugar is a p- or L- stereoisomer?(A) 1 (B)2 (C) 3 (D) 4 (E) 5

20. In glycoproteins, the carbohydrate moiety is always attached through the amino acid residues:(A)asparagine, serine, or threonine. (B) aspartate or glutamate. (C) glutamine or arginine.(D) glycine, alanine, or aspartate. (E) tryptophan, aspartate, or cysteine.

21. Bacteria and other prokaryotic cells have the capacity to get more ATP/glucose oxidized than eukaryotic cells because__________，so they are more efficient.(A) they are simpler and have less going on(B) they don't have to use shuttles to reoxidize reduced nucleotides(C) they do not have to translocate ATP-ADP across the mitochondrial membranes(D) they use an electron transport chain that translocates more protons(E) None of the above.

22 The standard reduction potentials (E'°) for the following half reactions are given. If you mixed succinate, fumarate, FAD, and FADH2 together, all at I M concentrations and in the presence of succinate dehydrogenase, which of the following would happen initially?(A) Fumarate and succinate would become oxidized; FAD and FADH2 would become reduced.(B) Fumarate would become reduced; FADH2 would become oxidized.(C) No reaction would occur because all reactants and products are already at their standard concentrations.(D) Succinate would become oxidized; FAD would become reduced.(E) Succinate would become oxidized; FADH2 would be unchanged because it is a cofactor.

23. Which of the following pairs is interconverted in the process of mutarotation?(A) D-glucose and D -fructose (B) D-glucose and D-galactose(C) D-glucose and D-glucosamine(D) D-glucose and L-glucose (E) a-D-glucose and β-D-glucose

24. The biochemical property of lectins that is the basis for most of their biological effects is their ability to bind to:(A) amphipathic molecules. (B) hydrophobic molecules. (C) specific lipids.(D) specific oligosaccharides. (E) specific peptides.