15. When fatty acids with an odd number of carbon atoms are oxidized via the β-oxidation pathway, which compound will propionyl-CoA be converted into?
(A) Acetyl-CoA
(B) Acetoacetyl-CoA
(C) Succinyl-CoA
(D) Malonyl-CoA
(E) All of the above are wrong

11. Which of the following statements is correct regarding the biosynthesis of purine nucleotides? (A) Glycine, aspartate, and glutamine serve as nitrogen sources for the purine ring. (B) The concentration of 5-phosphoribosyl 1-pyrophosphate is the major factor regulating the rate of de novo purine nucleotide biosynthesis. (C) Lesch-Nyhan syndrome is caused by a defect in hypoxanthine-guanine phosphoribosyl transferase, an enzyme involved in purine salvage. (D) AMP and GMP inhibit hypoxanthine-guanine phosphoribosyl transferase, which converts hypoxanthine and guanine into IMP and GMP. (E) All of the above are correct.

12. Which of the following is the correct nomenclature name for the unsaturated fatty acid shown below? (A) ω6, C20:5 (B) ω3, C20:5 (C) ω6, C20:6 (D) ω3, C20:6 (E) ω5, C20:5

13. Prostanoids are synthesized by (A) Pentose phosphate pathway (B) β-oxidation pathway (C) Lipoxygenase pathway (D) Cyclooxygenase pathway (E) All of the above are wrong

14. Which of the following compounds is not a ketone body? (A) Glycolic acid (B) Acetoacetate (C) D-3-Hydroxybutyrate (D) Acetone (E) All of the above are correct.

16. During intense physical activity, NADH generated in glycolysis is rapidly reoxidized by which reaction? (A) Reduction of pyruvate to lactate by lactate dehydrogenase. (B) Conversion of glucose-6-phosphate to fructose-6-phosphate. (C) Oxidation of dihydroxyacetone phosphate to glycerol-3-phosphate. (D) Reduction of oxaloacetate to malate. (E) Formation of citrate from oxaloacetate and acetyl-CoA.

17. Arsenic poisoning inhibits which enzyme of the citric acid cycle, thereby impairing oxidative metabolism? (A) Citrate synthase. (B) Malate dehydrogenase. (C) α-Ketoglutarate dehydrogenase. (D) Fumarase. (E) Aconitase.

18. Which glycolytic product serves as the primary precursor for entry into the citric acid cycle? (A) 2-Phosphoglycerate. (B) Glyceraldehyde-3-phosphate. (C) Pyruvate. (D) Glucose-6-phosphate. (E) Fructose-1,6-bisphosphate.

19. Which polysaccharide is found in the plant cell wall and provides structural support? (A) Glycogen (B) Amylopectin (C) Cellulose (D) Starch (E) Chitin

20. Which of the following glycolytic intermediates is directly involved in the generation of ATP through substrate-level phosphorylation? (A) Glucose-6-phosphate. (B) Phosphoenolpyruvate. (C) Fructose-1,6-bisphosphate. (D) Glyceraldehyde-3-phosphate. (E) 3-phosphoglycerate.

21. What is the major driving force for the formation of tertiary structures in cytoplasmic proteins? (A) Formation of peptide bonds. (B) Hydrogen bonding between backbone atoms. (C) Hydrophobic interactions among nonpolar side chains. (D) Covalent bonding between side chains of amino acids. (E) Ionic interactions between side chains of amino acids.