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.

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.

19. Bile is crucial for ______ digestion because of its function in _____. (A) protein, protecting the stomach lining (B) fat, solubilizing glycerol:fatty acid bonds (C)nucleic acids, uncoiling DNA strands (D) fat, emulsification (E) protein, lyophilization

20. Which animal would you predict would have the highest mass-specific metabolic rate? (A) a lizard (B) a squid (C) an elephant (D) a goose (E) a hummingbird

21. Which structure prevents blood flowing back into the atria during ventricular contractions? (A) atrioventricular valves (B) semilunar valves (C)sinoatrial node (D) carotid blood shunts (E) foramen ovale

22. Which of the following statements about RNA polymerase in bacteria is INCORRECT? (A) It binds the promoter region of a gene. (B) It is bound to a sigma factor during initiation of transcription. (C)It synthesizes RNA. (D) It catalyzes the addition of nucleotides to the 5′end of a growing RNA strand. (E) It dissociates from the DNA at the terminator.

23. Surgical removal of the pancreas would (A) increase the acidity of the small intestine. (B) prevent the production of chyme in the stomach. (C)eliminate the ability to store bile in the gallbladder. (D) block the secretion of bile. (E) All of these changes would be a result of pancreas removal.

24. What protein is involved in synthesizing messenger RNA in eukaryotes? (A) RNA polymerase I (B) RNA polymerase II (C)RNA polymerase III (D) sigma factor (E) both RNA polymerase I and II