16. Which of the following is true of glucagon?
(A) It is released from the pancreatic β-cells when glucose levels are low.
(B) Its synthesis and release are exclusively under the control of epinephrine.
(C) The primary targets of glucagon are liver, adipose and muscle tissues.
(D) Major pathways promoted by glucagon include glycogenolysis and glycolysis.
(E) None of the above.

12. Which is a characteristic of sphingolipids? (A) They all contain a fatty acid joined to glycerol. (B) They all contain a long-chain alcohol joined to isoprene. (C) They all contain ceramide joined to a polar group. (D) They all contain a carbohydrate joined to a phosphate group. (E) They all contain a polar head group and two non-polar fatty acids.

13. Which of these statements about triacylglycerol synthesis is correct? (A) Humans can store more energy in glycogen than in triacylglycerols. (B) Insulin stimulates conversion of dietary carbobydrate into triacylglycerols. (C) Triacylglycerols are the building blocks for cell membrane architecture. (D) Mammals are unable to convert carbohydrates into triacylglycerols. (E) Phosphatidic acid is not on the pathway of triacylglycerol synthesis.

14.What are the products of β oxidation of a saturated 20-carbon fatty acid? (A) 1 propionyl-CoA, 9 acetyl-CoA, 9 FADH2, and 9 NADH (B) 9 acetyl-CoA, 8 FADH2,8 NADH (C) 9 acetyl-CoA, 9 FADH2,9 NADH (D) 10 acetyl-CoA, 9 FADH2, 9 NADH (E) 10 acetyl-CoA, 10 FADH2, 10 NADH

15. For skeletal muscle, which of the following correctly pairs the activity state with the source of energy? (A) resting: glucose (B) resting: amino acids (C) exertion: glucose (D) exertion: fatty acids (E) None of the above.

17. Oxidation-reduction reactions in biological system always involve； (A) direct participation of oxygen. (B) transfer of electron(s). (C) mitochondria. (D) formation of water. (E) transfer of hydrogens.

18. Carotenoids have primary roles in photosynthesis as: (A) accessory light-harvesting and photooxidation. (B) accessory light-harvesting and photoprotection from reactive oxygen species. (C) resonance transfer pigments and photooxidation. (D) resonance transfer and photodiffusion protection. (E) None are true.

19. Epinephrine triggers an increased rate of glycolysis in muscle by: (A) activation of hexokinase. (B) activation of phosphofructokinase-1. (C) conversion of glycogen phosphorylase a to glycogen phosphorylase b. (D) inhibition of the Cori Cycle. (E) the Pasteur effect.

20. Which of the following reactions in glycolysis is a ketose to aldose isomerization? (A) Hexokinase (B) Phosphoglycerate mutase (C) Enolase (D) Aldolase (E) Triose phosphate isomerase

21. When carbohydrate intake is low,______ are formed from acetate units to provide metabolic fuel for the ______and other tissue. (A) fatty acids； liver (B) ketone bodies； brain (C) ketone bodies； liver (D) amino acids； brain (E) sterols； heart

22. The_______ of pyruvate to acetyl-CoA is catalyzed by_______. (A) dehydration； pyruvate dehydration complex (B) decarboxylation； pyruvate dehydrogenase complex (C) decarboxylation； pyruvate decarboxylase (D) transacylation； pyruvate transacylase (E) None of the above.