23. Which of the following statements about renin-angiotensin-aldosterone system (RAAS) is FALSE?
(A) Sensors in juxtaglomerular apparatus (JAG) detect decrease in pressure.
(B) JAG releases renin with decreased pressure.
(C) Renin cleaves angiotensinogen to produce angiotensin I.
(D) Angiotensin II stimulates the kidney to release aldosterone.
(E) Aldosterone increases blood volume by Na+ and water reabsorption.

19. Which of the following is in the correct order for one cycle of polymerase chain reaction (PCR)? (A) Denature DNA; add fresh enzyme; anneal primers; add dNTPs; extend primers. (B) Anneal primers; denature DNA; extend primers. (C) Denature DNA; anneal primers; extend primers. (D) Extend primers; anneal primers; denature DNA. (E) Add dNTPs; add fresh enzyme; denature DNA.

20. Which of the following definition is WRONG for molecular clock? (A) Paralogous genes are used. (B) Constant mutation rate is supposed. (C) Fossil record can be used to correct dating. (D) Based on Neutral theory. (E) The rate of molecular change should be regular like a clock.

21. If organisms a, b, and c belong to the same class but to different orders and if organisms c, d, and e belong to the same order but to different families, which of the following pairs of organisms would be expected to show the greatest degree of structural homology? (A) a and d (B) b and c (C) b and d (D) d and e (E) a and e

22. Which of the following plants has a dominant sporophyte generation and a seed, but no fruit? (A) fern (B) pine tree (C) tulip (D) lycophyte (E) moss

24. A biologist doing a long-term study on a wild spider population observes increased variation in silk thickness. Which of the following could the spider population be experiencing? (A) directional selection (B) genetic drift (C) disruptive selection (D) stabilizing selection (E) founder effect

25. Two species of frogs belonging to the same genus occasionally mate, but the embryos stop developing after a day and then die. These two frog species separate by ______. (A) gametic isolation (B) reduced hybrid fertility (C) hybrid breakdown (D) mechanical isolation (E) reduced hybrid viability

26. Which of the following characteristics tends to limit bryophytes and seedless vascular plants to habitats that are relatively moist? (A) absence of cuticle (B) presence of flagellated sperm (C) presence of free-living, independent zygotes and early embryos (D) presence of lignified vascular tissues (E) presence of seeds and pollen

27. There are several stages about alternation of generations of ferns. Which order is TRUE? (1) gametophyte, (2) sporophyte, (3) spores, (4) archegonia, (5) gametes. (A) 32541 (B) 23145 (C) 32451 (D) 23541 (E) 32145

28. Compare with Monocots and Eudicots, which of the following statements is FALSE? (A) A seed of Monocots has one cotyledon; that of Eudicots has two. (B) Leaf vein of Monocots is usually parallel, but that of Eudicots is usually netlike. (C) Vascular tissue of stems in Monocots is scattered, but that of Eudicots is usually arranged in ring. (D) Pollen grain of Monocots has one opening; that of Eudicots has three openings. (E) Floral organs usually in multiple of four in Monocots, but three in Eudicots.

29. Which structure is found in angiosperms but NOT gymnosperms? (A) fruit (B) spores (C) seeds (D) ovule (E) a tube that grows from the pollen to deliver sperm