46. The ratio of NADP+/NADPH in liver runs about 1/67 which means that:
(A) it is similar to the ratio of NAD⁺/NADH.
(B) glucose-6-phosphate dehydrogenase will be turned on most of the time.
(C) glucose-6-phosphate is rate limiting for pentose phosphate pathway.
(D) glucose-6-phosphate preferentially goes to the pentose phosphate pathway.
(E) glucose-6-phosphate dehydrogenase activity is dependent upon use of some of the NADPH before activity increases.

42. Glucose breakdown in certain mammalian and bacterial cells can occur by mechanisms other than classic glycolysis. In most of these, glucose 6-phosphate is oxidized to 6-phosphogluconate, which is then further metabolized by:(A) an aldolase-type split to form glyceric acid and glyceraldehyde 3-phosphate.(B) an aldolase-type split to form glycolic acid and erythrose 4-phosphate.(C) conversion to 1,6-bisphosphogluconate.(D) decarboxylation to produce keto- and aldopentoses.(E) oxidation to a six-carbon dicarboxylic acid.

43.______ is often used in carboxylation reactions while________ is often used in decarboxylation reactions.(A) thiamine pyrophosphate; lipoate (B) lipoate; biotin (C) biotin; thiamine pyrophosphate(D) pyridoxal-5-phosphate; biotin (E) lipoate; pyridoxal-5-phosphate

44. In the citric acid cycle, citrate is isomerized to isocitrate by aconitase. H2O was first abstracted from citrate, and then rehydrated with H- and HO–adding back in opposite positions to produce isocitrate. This reaction catalyzed by aconitase is quite stereospecific. As citrate has a total of four chemically equivalent hydrogens (labeled as H1~H4 in the figure), only one of the four hydrogens, the pro-R H atom of the pro-R arm of citrate, is abstracted during the reaction of theH2O abstraction by aconitase.Which one of the hydrogens in the citrate molecule shown in the figure is the pro-R H atom of the pro-R arm?(A) H1 (B) H2 (C) H3 (D)H4 (E) None of them.

45. Which of the following monosaccharides is an aldose?(A)a(B) b (C)c (D)d (E) None of the above.

47. In an anaerobic muscle preparation, lactate formed from glucose labeled in C-2 would be labeled in:(A) all three carbon atoms.(B) only the carbon atom carrying the OH.(C) only the carboxyl carbon atom.(D)only the methyl carbon atom.(E) the methyl and carboxyI carbon atoms.

48. In the glycolytic pathway, there is an isomerization of glucose 6-phosphate to fructose 6-phosphate occurs two steps before the C-C bond cleavage reaction between C3 and C4 to produce two three-carbon sugars. Where would the bond cleavage occur if there is no preceding isomerization?(A) Without isomerization, bond cleavage would occur between C2 and C3.(B) Without isomerization, bond cleavage would occur between C3 and C4.(C) Without isomerization, bond cleavage would occur between C4 and C5.(D) Without isomerization, bond cleavage would occur between C5 and C6.(E) Without isomerization, bond cleavage would occur between C1 and C2.

49. Nucleic acid hybridization is a commonly employed procedure in molecular biology to investigate all except:(A) evolutionary relationships. (B) specific genes against a vast background.(C) specific probe based isolation of genes. (D) quantify gene expression. (E) All are true.

50. What coenzyme would be required in the following reaction?(A) ADP(B) thiamine pyrophosphate (C) biotin (D) lipoic acid (E) coenzyme A

複選題 26.傾斜生長的樹幹往往會偏心生長,使得部分年輪寬度較大而部分年輪寬度較窄。下列有關描述正確的有： (多選) (A)圖 A 在傾斜生長的楊樹主莖幹下部， 會形成窄年輪； (B)圖 A 在傾斜生長的楊樹主莖幹上部， 會形成寬年輪； (C)圖 B 在傾斜生長的楊樹主莖幹下部， 會形成窄年輪； (D)圖 B 在傾斜生長的楊樹主莖幹上部， 會形成寬年輪。

複選題27.下列有關圖 B 的描述錯誤的有：(多選) (A) 大部分細胞次生壁明顯增厚，其機械支撐力增加； (B) 大部分細胞次生壁明顯增厚，其拉伸力增加； (C) 大部分細胞細胞腔減小，其水分疏導能力下降； (D) 大部分細胞細胞腔減小，其水分疏導能力提高。