23. Entry of acetyl-CoA into the citric acid cycle is decreased when:
(A)the ratio of /[NADH] is high.
(B) NADH is rapidly oxidized through the respiratory chain.
(C) the ratio of [ATP]/[ADP] is low
(D) the ratio of [ATP]/[ADP] is high.
(E) [AMP] is high.

19. Which of the following molecules or substances contain, or are derived from, fatty acids? (A)sphingolipids (B) prostaglandins (C) beeswax (D) all of the above (E) none of the above

20. The fluidity of the lipid side chains in the interior of a bilayer is generally increased by: (A)an increase in temperature. (B) an increase in fatty acyl chain length. (C) a decrease in the number of double bonds in fatty acids. (D) an increase in the percentage of phosphatidyl ethanolamine. (E) all of the above.

21. Which of these statements is generally true of integral membrane proteins? (A)Their hydropathy plots reveal one or more regions with a high hydropathy index. (B) They are glycosylated. (C) They are more stable than cytosolic proteins. (D) They undergo constant rotational motion that moves a given domain from the outer face of a membrane to the inner face and then back to the outer. (E) None of the above.

22. Which of the following molecules cannot serve as the starting material for the synthesis of glucose via gluconeogenesis in mammals? (A)glycerol (B) lactate (C) glycine (D) oxaloacetate (E) acetate

24. Which enzyme is the major regulatory control point for β-oxidation? (A)pyruvate carboxylase (B) acetyl CoA dehydrogenase (C) methylmalonyl CoA mutase (D) enoyl CoA isomerase (E) carnitine acyl transferase I

25. The major regulator of sucrose biosynthesis in plants is: (A)fructose 6-phosphate (B) glucose 6-phosphate (C) fructose 1,6-bisphosphate (D) fructose 2,6-bisphosphate (E) sucrose 

複選題1. Which of the following are DNA sequences? (A) Promoter (B) Repressor (C) Operator (D) Enhancer (E) Activator

2. When bacteria produce mammalian proteins, cDNA is used rather than genomic DNA. Which of the following is the best explanation? (A) It is easier to clone RNA than DNA. (B) It is not possible to clone the entire coding region of the gene. (C) It is easier to clone cDNA than genomic DNA of comparable size. (D) Most eukaryotic genes have introns that cannot be removed in bacteria. (E) Most eukaryotic gene promoters do not function in bacteria

3. Below is an electron micrograph of a gene that is being transcribed. The DNA strand runs horizontally with RNA transcripts extending vertically outward. What is the direction of movement of RNA polymerases along the length of DNA strand? (A) Upward (B) Downward (C) Rightward (D) Leftward (E) Can't be determined

複選題4. Which of the following statements are true? (A) Bacterial mRNA normally occurs as a double-stranded structure, with one strand containing codons, the other containing anticodons. (B) Bacterial mRNA is broken down within a few minutes of its formation in E. coli. (C) Bacterial mRNA consists only of the bases that code for amino acids. (D) The three ribosomal RNAs in a bacterial ribosome are distributed in three separate, large ribosomal subunits. (E) Bacterial mRNA can be translated while it is still being synthesized.