37. Free fatty acids in the liver have four possible fates. Which one is     not correct    ? They can be
(A) metabolized by ẞ oxidation in mitochondria.
(B) stored as triacylglyderol in lipid droplets.
(C) used to form phosphotidylcholine.
(D) packaged with apoB into VLDL.
(E) turned into acetyl-CoA in the cytosol.

33. Which one of the following statements about gluconeogenesis is     not true    ? (A) If the reactions of gluconeogenesis were simply the reactions of glycolysis in reverse, the process would be energetically unfeasible (highly endergonic). (B) The conversion of pyruvate to phosphoenolpruvate in gluconeogenesis requires both pyruvate carboxylase and phosphoenolpyruvate carboxykinase. (C) The first step in the synthesis of glucose from lactate in the liver is oxidation of the lactate to pyruvate. (D) Ingesting sodium succinate cannot promote gluconeogenesis. (E) None of the above.

34. Which one of the following statements statements about the citric acid cycle is     not true    : (A) Oxaloacetate is used as a substrate but is not consumed in the cycle. (B) In the presence of malonate, one would expect succinate to accumulate. (C) Succinate dehydrogenase channels electrons directly into the electron transfer chain. (D) The condensing enzyme is subject to allosteric regulation by ATP and NADH. (E) All enzymes of the cycle are located in the cytoplasm, except succinat dehydrogenase, which is bound to the inner mitochondrial membrane.

35. Which of the following statements is     true    : (1) In glyoxylate cycle, conversion of isocitrate to succinate replaces the two reductive reactions of the TCA cycle. (2) Isocitrate dehydrogenase catalyzes the conversion of isocitrate to succinate and glyoxylate. (3) Glyoxylate + acetyl-CoA → Coenzyme A + malate catalyzed by malate synthase. (4) Glyoxylate + acetyl-CoA → Coenzyme A + malate occurs in mitochondria. (5) Using glyoxylate cycle, plants can use the acetyl-CoA produced in fatty acid metabolism to produce oxaloacetate and other intermediates for carbohydrate synthesis. (A) 3 and 5. (B) 1, 3, and 5. (C) 1, 2, 3, and 5. (D) 1, 3, 4, and 5. (E) All of the above.

36. Which one is     not correct    ? (A) Insulin mobilizes GLUT4 in muscle and adipose tissue. (B) Glucose is cotransported with across intestinal epithelial cells. (C) Glucose passes intestinal epithelial cells into the blood via GLUT2. (D) ATPase pump outward. (E) AQP-2 is regulated by vasopressin to allow glycrerol or urea to pass.

38. Assuming that you are attending a triathlon, which one will     not     occur? (A) Ketone bodies are accumulating in the brain. (B) Proton pump is increasing concentration in the stomach. (C) Bicarbonate is increasing in the blood. (D) Aquaporin is lowering its water reabsorption in the renal tubes. (E) Malonyl-CoA is inhibiting ẞ oxidation.

39. Which of the following statements is     false    ? (A) Animals can produce tyrosine directly from phenylalanine. (B) 1-Dopa is an intermediate in the conversion of tyrosine to epinephrine. (C) Bile pigments are formed in the degradation of heme. (D) Histidine undergoes amination to histamine. (E) Asparagine can be synthesized by amidation of aspartate, thus it is not an essential amino acid in human.

40. Which of the following descriptions is      false    ? (A) When a solution of double-stranded DNA is heated at neutral pH, the absorption of ultraviolet (260 nm) light may increase. (B) Double-stranded regions of RNA can form between two self-complementary regions of the same single strand of RNA. (C) Lowering the ionic strength of a solution of double-stranded DNA will decrease the melting temperature of the DNA: (D) The Hoogsteen (non Watson-Crick) interaction, which can result in triple-helical DNA structures, are primarily hydrophobic interactions involving the bases. (E) In nucleotides and nucleic acids, syn and anti conformations relate to rotation around the sugar-base bond.

41. Which of the following statements is     correct     of the biosynthetic pathways for purine and pyrimidine nucleotides? (1) The amino acid aspartate is directly involved in the purine biosynthetic pathway. (2) 5-Phosphoribosyl-1-pyrophosphate (PRPP) is a synthetic precursor for UMP. (3) Orotic acid is an essential precursor for purine nucleotides.  (4) Inosinate is the precursor for the synthesis of pyrimidine nucleotides. (5) The carbamoyl phosphate required in pyrimidine biosynthesis is made in the cytosol by carbamoyl phosphate synthetase II. (A) 1 and 4. (B) 1, 2, and 3. (C) 4 and 5. (D) 1, 2, and 5. (E) 2 only.

42. The primary source of one-carbon units for tetrahydrofolate in the cells is the carbon removed in the conversion of to homocystein. (A) methionine to homocystein. (B) serine to pyruvate. (C) N-methyltetrahydrofolate to tetrahydrofolate. (D) serine to glycine. (E) S-adenosylmethionine to S-adenosylhomocystein.

43. Which of the following statements regarding plasmid cloning vectors is     correct    ? (1) Foreign DNA fragments up to 30,000 base pairs cannot be cloned in a typical plasmid vector. (2) Plasmid vectors must carry promoters for inserted gene fragments. (3) The copy number of plasmids may vary from a few to several hundred. (4) In the laboratory, microinjection is commonly used to introduce recombinant plasmids into bacterial cells. (5) The replication origin (ori sequence) in plasmid cloning vectors is a sequence required for packaging recombinant plasmids into bacteriophage. (A) 1 and 2. (B) 3 and 5. (C) 1, 2, and 4. (D) 1 and 3. (E) 3 only.