16. ________ are commonly referred to, respectively, as the 21st and 22nd amino acids.
(A) Selenocysteine and pyrrolysine
(B) Adenine and guanine
(C) Thymine and uracil
(D) Hydroxyproline and hydroxylysine
(E) β-Alanine and D-alanine

12. Testosterone is synthesized primarily by the ________. (A) Leydig cells (B) hypothalamus (C) sperm cells (D) anterior pituitary gland (E) seminiferous tubules

13. Which of the following orders regarding mammalian embryogenesis is correct? 1. cleavage 2. gastrula 3. blastula 4. cortical reaction 5. neurulation 6. acrosomal reaction (A) 132645 (B) 231546 (C) 461523 (D) 641325 (E) 654132

14. Which of the following descriptions regarding the embryonic germ layers is correct? (A) Pituitary gland is derived from mesoderm. (B) Thymus is derived from mesoderm. (C) Teeth are derived from mesoderm. (D) Adrenal cortex is derived from mesoderm. (E) Adrenal medulla is derived from mesoderm.

15. Which of the following about chloroplasts and mitochondria is incorrect? (A) They are of the appropriate size to be the descendants of bacteria. (B) They contain circular DNA not associated with histones. (C) They contain their own genome and produce all proteins they need. (D) Their ribosomes are more similar to those of bacteria than to those of eukaryotes. (E) Their membranes have enzymes and transport systems that resemble those in the plasma membrane of prokaryotes.

17. Which of the following sequences is not found in an E. coli vector (such as pET21)? (A) replication origin (ori) (B) multiple cloning sites (MCS) (C) antibiotic resistance gene (AmpR ) (D) Shine-Dalgarno sequence (E) CMV promoter

18. Which of the following metabolic pathways is strictly anabolic? (A) glycolysis (B) gluconeogenesis (C) citric acid cycle (D) pentose phosphate cycle (E) β-oxidation of fatty acids

19. Dihydrouracil and pseudouridine are found predominantly in ________. (A) mRNA (B) rRNA (C) tRNA (D) Z form DNA (E) siRNA

20. Which oil listed below contains more than 60% unsaturated fatty acids? (A) beef (B) milk (C) coconut (D) palm (E) olive

21. In order to perform PCR, the following reagents must be included ________. (A) DNA fragment, primers flanking the region of interest, dNTPs, ddNTPS, DNA Polymerase (B) DNA fragment, primers flanking the region of interest, dNTPs, DNA Polymerase (C) DNA fragment, one primer, dNTPs, DNA Polymerase, DNA ligase (D) DNA fragment, primers flanking the region of interest, dNTPs, DNA Ligase (E) none of the above

22. The coding sequence of DNA is 5’-CGCTATAGCGTTT-3’. Which of the following sequences is its RNA transcript (mRNA)? (A) 3’-CGCTATAGCGTTT-5’ (B) 5’-CGCUAUAGCGUUU-3’ (C) 3’-GCGATATCGCAAA-5’ (D) 5’-UUUCGCUAUAGCG-3’ (E) 5’-CGCTATAGCGTTT-3’