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.

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.

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.

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

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.

25. The citric acid cycle is considered part of acrobic metabolism even though oxygen does not appear explicitly in any reaction because:(A) it contains oxidative decarboxylation of isocitrate to succinyl-CoA.(B) it takes place in the mitochondrion.(C) the reoxidation of NADH and FADH2 leads to the production of considerable quantities of ATP.(D) it consumes H2O molecule.(E) the NADH and FADH2 produced are reoxidized in the electron transport chain linked to oxygen.

26. Immobilized metal affinity chromatography (IMAC) is an important tool for recombinant protein purifications.Nickel (Ni2+) nitriloacetic acid (Ni-NTA) agarose is a commonly used affinity resin for IMAC. Which of the following peptide motif is often engineered to the target protein for IMAC-based purifications?(A) Polyalanine (B) Polyhistidine (C) Polylysine (D) Polyproline (E) Polyglycine