12. The lacteal, a lymphatic vessel in the center of each intestinal villus, functions in digestion by absorbing
(A)carbohydrates.
(B)proteins.
(C)nucleic acids.
(D) vitamin C.
(E) lipids.

8. Unlike bacteria, archaea cell walls not contain a substance called (A)cellulose. (B)peptidoglycan. (C)phospholipid. (D) glycogen. (E) proteinoid.

9. The critical function of the sodium-potassium pump of neurons is to move (A)Na+ and K+ into the cell. (B)Na+ and K+ out of the cell. (C)Na+ into the cell and K+ out of the cell. (D) Na+ out of the cell and K+ into the cell. (E) Na+ and K+ into the cell and H+ out of the cell through an antiport mechanism.

10. Which of the following characteristics is common to both viruses and bacteria (A)infection pathway (B)generalized transduction (C)lytic replication (D) genetic variation by mutation (E) intracellular parasites

11. The neurotransmitter released at neuromuscular junctions in vertebrates is (A)acetylcholine. (B)serotonin. (C)epinephrine. (D) GABA. (E) endorphin.

13. Which of the following is a true statement about virus (A) all viruses have capsids and membrane envelope (B)viral RNA genome can be reversely transcribed into DNA by retrovirus (C) RNA viruses can serve as a template for DNA synthesis (D) viruses have lysogenic cycle (E) all of the above

14. Which of the following is not the components of an operon (A)operator. (B)promoter. (C)co-repressor. (D) structural genes. (E) None of above.

15. Which of the followings is NOT true for cilia or flagella? (A)They are involved in cell motility. (B)They require ATP to work. (C)They are composed of microfilaments. (D) They require motor proteins to work. (E) They are composed of an internal structure called the axoneme.

16. Which of the following scientist-discoveries is mismatched? (A)Watson and Crick – DNA structure. (B)Griffith – DNA is genetic material. (C)Meselson and Stahl – DNA replication mechanism. (D) Mendel – genetic inheritance. (E) None of above.

17. Which of the following statements best describes DNA polymerase? (A)It is an enzyme required to produce a primer needed for DNA replication. (B) It is an enzyme that catalyzes the addition of nucleotides to the 5′ end of a growing DNA strand. (C) It is an enzyme that catalyzes the addition of nucleotides to the 3′ end of a growing DNA strand. (D) It is an enzyme required to glue pieces of DNA fragments together. (E) It is an enzyme that polymerizes the DNA and keeps the replication fork open.

18. A DNA specimen that contains 30% guanine has ________ thymine. (A)10% (B)20% (C)30% (D) 40% (E) The amount of thymine cannot be determined.