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

8. In a phylogenetic tree, a group is composed of some species but not their most recent common ancestor. This is an example of ________. (A) monophyletic group (B) paraphyletic group (C) polyphyletic group (D) polytomy (E) dicotomy

9. Bioluminescence is an important strategy for attracting preys in which of the following marine zone? (A) benthic zone (B) intertidal zone (C) oceanic zone (D) aphotic zone (E) photic zone

10. Which of the following descriptions regarding sensory receptors is correct? (A) Sense of smell is generated through mechanoreceptors. (B) Vision is generated through chemoreceptors. (C) Thermoreceptors detect change of pressures. (D) Nocireceptors detect pain feelings. (E) Photoreceptors detect sense of taste.

11. Which statement is incorrect concerning protein translation? (A) Ribosomes in prokaryotic and eukaryotic cells have two subunits of unequal size. (B) Sequences exist in prokaryotic and eukaryotic rRNA that are so similar, that they likely derive from a common ancestor. (C) Initiator tRNA recognizes AUG codons during initiation at the P site of ribosome. (D) The 30S and 50S ribosomal subunits of E. coli combine to generate an 80S subunit. (E) Polysomes are rich in cells active in protein synthesis.

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.

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

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