19. In amino acid catabolism, the first reaction for many amino acids is a(n):
(A) oxidative deamination requiring NAD+.
(B) hydroxylation requiring NADPH and O2.
(C) transamination requiring pyridoxal phosphate (PLP).
(D) reduction requiring pyridoxal phosphate (PLP).
(E) decarboxylation requiring thiamine pyrophosphate (TPP).

15. Ketone bodies are used as fuels in all tissues except liver, which lacks: (A) β-ketoacyl-CoA transferase (B) HMG-CoA synthase (C) HMG-CoA reductase (D) HMG-CoA lyase (E) thiolase

16. Acyl carrier protein (ACP) is an important part of fatty acid biosynthesis because: (A) ACP binds the final product of fatty acid synthase to transport it to other places in the cell. (B) ACP connects the acetyl-CoA carboxylase with fatty acyl chain. (C) ACP covalently links with the acyl group from one active site to another in sequence. (D) ACP is essential only for the thioesterase activity that releases the product fatty acid from the enzyme. (E) ACP provides a way to store pantothenic acid when abundant so it is available during times when the amount of this vitamin in the diet is inadequate.

17. How many are reduced in the degradation of palmitoyl-CoA to form eight molecules of acetyl-CoA? (A) 1 (B) 7 (C) 8 (D) 14 (E) 16

18. Insulin is able to stimulate some lipid synthesis, including: (1) cholesterol (2) fatty acid (3) phospholipids (4) triacylglycerol (5) sphingolipids (A) (2) and (4) (B) (1), (2), and (5) (C) (2), (3), and (4) (D) (2) only (E) (1), (2), and (4)

20. The light-induced changes in chloroplasts which regulate key Calvin cycle enzymes include all except: (A) activation of rubisco activase. (B) Mg2+ efflux from the thylakoid lumen. (C) changes in stromal pH. (D) generation of reducing power. (E) All are true.

21. Initiation of gluconeogenesis occurs in the pyruvate carboxylase reaction, which converts pyruvate to oxaloacetate. In this pyruvate carboxylase catalyzed reaction, bicarbonate is "activated" by attachment to the _____ of ATP to form _____. (A) β-phosphate; carbonyl ADP (B) α-phosphate; carbonyl AMP (C) α-phosphate; carbonylphosphate (D) γ-phosphate; carbonylphosphate (E) γ-phosphate; carbonyl AMP

22. The oxidation of a particular hydroxy substrate to a keto product by mitochondria has a P/O ratio of less than 2. The initial oxidation step is very likely directly coupled to the: (A) oxidation of a flavoprotein. (B) oxidation of a pyridine nucleotide. (C) reduction of a flavoprotein. (D) reduction of a pyridine nucleotide. (E) reduction of cytochrome a3.

23. The NADH produced by glycolysis produces different amounts of ATP in different tissues. This is because: (A) different tissues have different shuttle system to transport cytosolic NADH into mitochondria. (B) the averaged amounts of mitochondria in the cells of different tissues are different. (C) the efficiency of the respiratory chain in different tissues are different. (D) some tissues can utilize cytosolic NADH to produce ATP; however, some tissues cannot. (E) different tissues have different energy need.

24. Energy balance in the cell (ATP/ADP/AMP levels) is an important factor in the metabolic pathways we have studied. How does this regulation take place? (A) ATP, ADP and/or AMP bind to DNA to modulate transcription of genes for enzymes involved in metabolism. (B) ATP, ADP and/or AMP bind to enzymes involved in metabolism, allosterically changing the enzyme activity. (C) High levels of ATP result in nonenzymatic phosphorylation of the enzymes involved in metabolism, changing their activity. (D) High levels of ATP result in excessive production of cyclic AMP, causing activation of pathways such as glycogenolysis and gluconeogenesis. (E) None of the above.

25. When a muscle is stimulated to contract aerobically, less lactic acid is formed than when it contracts anaerobically because: (A) glycolysis does not occur to significant extent under aerobic conditions. (B) muscle is metabolically less active under aerobic than anaerobic conditions. (C) the lactic acid generated is rapidly incorporated into lipids under aerobic conditions. (D) under aerobic conditions in muscle, the major energy-yielding pathway is the pentose phosphate pathway, which does not produce lactate. (E) under aerobic conditions most of the pyruvate generated as a result of glycolysis is oxidized by the citric acid cycle rather than reduced to lactate.