15. What major benefits do plants and mycorrhizal fungi receive from their symbiotic relationship?
(A) Fungi receive photosynthetic products in exchange for living in plant root nodules.
(B) Plants receive nitrogen and phosphorus, and fungi receive photosynthetic products.
(C) Plants receive enzymes, and fungi receive nitrogen and phosphorus.
(D) Plants receive increased root surface area, and fungi receive digestive enzymes.
(E) All of the above are false.

11. Jams, jellies, preserves, honey, and other foods with high sugar content hardly ever become contaminated by bacteria, even when the food containers are left open at room temperature. This is because bacteria that encounter such an environment ______. (A) are unable to swim through these thick and viscous materials (B) undergo death as a result of water loss from the cell (C) are unable to metabolize the glucose or fructose, and thus starve to death (D) are obligate anaerobes (E) are unable to reproduce then die eventually

12. Sympatric species ______. (A) are more likely than allopatric species to display character displacement (B) always show character displacement (C) are less likely than allopatric species to display character displacement (D) are unlikely to be competing (E) are more likely than allopatric species to display character displacement and likely to be competing

13. The veins of leaves are ______. I) composed of xylem and phloem II) continuous with vascular bundles in the stem and roots III) finely branched to be in close contact with photosynthesizing cell (A) only I (B) only II (C) only III (D) I and II (E) I, II, and III

14. To be useful to plants soil nitrogen must usually occur as: (A) N2 and NH3 (B) NH3 and NO3 - (C) NO3 - and N2 (D) N2 and NO2 (E) NO2 and NO3 -

16. Which of the following statements about vitamins is FALSE? (A) Thiamine is a coenzyme in removing CO2 and relates to Beriberi. (B) Folic acid is a component of coenzyme A and relates to birth defect. (C) Ascorbic acid is a coenzyme in collagen synthesis and relates to scurvy. (D) Retinol is a component of visual pigments and relates to blindness. (E) Tocopherol is an antioxidant and relates to nervous system degeneration.

17. Pollen from a plant with the S1S2 genotype is recognized and allowed to germinate on the stigma of the same plant with the S1S2 genotype. According to the S-system hypothesis, this indicates that the plant is ______. (A) self-incompatible and must cross-pollinate (B) self-incompatible and can self-pollinate (C) self-compatible and must cross-pollinate (D) self-compatible and can self-pollinate (E) self-compatible and can self-pollinate or cross-pollinate

18. DNA methylation and histone acetylation are examples of ______. (A) genetic mutation (B) epigenetic phenomena (C) translocation (D) chromosomal rearrangements (E) gene degradation

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