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 glucose 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 and T = 298 K)

Glucose 6-phosphate fructose 6-phosphate
(A) is +1.7 kJ/mol.
(B)  is-1.7 kJ/mol. 
(C) is incalculably large and negative.
(D) is incalculably large and positive.
(E) 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. of the nucleotide serves as an information symbol, channeling

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

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

20. In glycoproteins, the carbokydrate 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 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) o-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.