5. When O₂ binds to heme in hemoglobin, the ____ ion is drawn into the plane of the ____ causing a conformational change that is transmitted to adjacent subunits enhancing the ________ for additional O₂ binding.
(A) ； globin； planarity.
(B) ； heme； folding.
(C) ； globin； attraction.
(D) ； porphyrin； affinity.
(E) ； porphyrin； affinity.

1. Please choose the correct answer from the following descriptions: 1. Protein sectors are evolutionary units of three-dimensional structure. 2. The α-D-glucose and β-D-glucose interconvert in aqueous solution.  3. Lectin is the exoskeleton of insects. 4. β-Keratin is Gly and Pro rich. 5. The pl of histidine is around 6. (A) 1 and 2 are correct. (B) 1, 3 and 4 are correct. (C) 1 and 5 are correct. (D) 2, 3 and 4 are correct. (E) Only 4 and 5 are incorrect.

2. Which description is correct? (A) Lipopolysaccharide is a dominant feature of the outer membrane of the cell wall of gram-negative bacteria. (B) Trypsin could hydrolyze the "X-K" peptide bond. (C) Orthologous genes are presumed to have been derived by gene duplication followed by gradual changes in the sequences of both copies. (D) Collagen is full of α-helix structure and has Gly-X-Pro repeating sequence. (E) For naming the RS system, -CH2OH group has higher priority than -CHO group.

3. Please choose the correct answer from the following descriptions: (1) Comparing amino acids "C" and "S", there is only one atom difference. (2) For two-dimensional gel electrophoresis, proteins were separated according to their molecular weights, then further separated according to their pl values. (3) Using solid state peptide synthesis to synthesize the peptide "SMART", the synthesis sequence is T-R-A-M-S.  (4) Phenylisothiocyanate is used to do chemical fragmentation on methionine residues.  (5) Evolutionary relatedness can be inferred from sequence homology. Lysozyme and α-lactoalbumin are identical at 48 positions but their functions are not related. It is called "convergent evolution". (A) Only 1 and 3 are incorrect. (B) Only 2 and 4 are incorrect. (C) Only 2, 4 and 5 are incorrect. (D) Only 3 is correct. (E) Only 1 and 5 are correct.

4. Both water and glucose share an -OH that can serve as a substrate for a reaction with the terminal phosphate of ATP catalyzed by hexokinase. Glucose, however, is about a million times more reactive as a substrate than water. The best explanation is that: (A) glucose has more -OH groups per molecule than does water. (B) the larger glucose binds better to the enzyme； it induces a conformational change in hexokinase that brings active-site amino acids into position for catalysis. (C) the -OH group of water is attached to an inhibitory H atom, while the glucose -OH group is attached to C. (D) water and the second substrate, ATP, compete for the active site resulting in a competitive inhibition of the enzyme. (E) water normally will not reach the active site because it is hydrophobic.

6. BPG shifts the oxygen saturation curve of Hb to the ____ because BPG binds to ____ making Hb an O2 delivery system eminently suited for human. (A) right； deoxyHb. (B) right； oxyHb. (C) left； oxyHb. (D) left； deoxyHb. (E) none of the above.

7. In E. coli, rotation of the flagella is powered by: (A) phosphorylation of the motB protein by phosphoenolpyruvate. (B) a proton gradient across the plasma membrane of the bacterium. (C) the hydrolysis of ATP by the motB protein. (D) the hydrolysis of GTP by the flagella. (E) None of the above.

8. Which of the following compounds can not serve as the starting material for the synthesis of glucose via gluconeogenesis? (A) Lactate. (B) Oxaloacetate. (C) Acetate. (D) α-Ketoglutarate. (E) Glycerol.

9. Which of the following statements about citric acid cycle is true? (1) Citric acid cycle plays roles in both catabolism and anabolism. (2) All enzymes of the cycle are located in the matrix, except malate dehydrogenase. (3) Both oxidation and decarboxylation reactions are involved in the generation of α-ketoglutarate from isocitrate. (4) The enzyme catalyzed the production of citrate is an allosteric enzyme that is inhibited by NADH, ATP, and succinyl-CoA.  (5) The step involves FAD in the citric acid cycle before the step that generates GTP. (A) 1, 2, and 4 are true. (B) 1, 3, 4 and 5 are true. (C) 1, 3, and 4 are true. (D) 1, 2, 3, and 4 are true. (E) All are true.

10. Which one of lipid metabolites does not act as a biological signal? (A) Arachidonic acid. (B) Lysophosphatidic acid. (C) Wax. (D) Inositol phosphates. (E) Sphingosine-1-phosphate.

11. Which one does not mainly distribute on the outer leaflet of the plasma membrane? (A) Glycoprotein. (B) Glycolipid. (C) GPI-anchored protein. (D) Phosphatidylcholine. (E) Phosphatidylserine.