21. About the phytochrome, which one of the following is the best answer?
(A)Pr and Pfr are the same protein.
(B) Pr can trigger the flower gene of long-day plant.
(C) Pfr can trigger the flower gene of short-day plant.
(D)During the night time, the flash of light can increase the level of Pr
(E)The night-length can be broken by the flash of light, likewise, the day-length can be broken by covering the black tank.

17. About the light reaction of photosynthesis, which one of the following is the best answer? (A)Photosystem II contains both chlorophyll a and chlorophyll b molecules. (B) Photons with wave length 680 nm can push the phosphor atom to attach on ADP. (C) Photons with wave length 680 nm can push the phosphor atom to attach on ATP. (D)Cyclic electron flow can produce ATP and NADPH. (E)Cyclic electron flow is triggered by photosystem II.

18. About the ATP production in the light reaction of photosynthesis, which one of the following is the best answer? (A)The concentration of H+ in the stroma is higher than thylakoid space during non-cyclic electron flow. (B) H+ can transport across membrane through plastocyanin (Pc) and ATP synthase. (C) H2O can continuously supply new H+ to elevate the H+ gradient between thylakoid membranes. (D)The final electron acceptor of non-cyclic electron flow is NADH reductase. (E)The ATP is produced inside the thylakoid space.

19. In C4 plants, the gaseous CO2 can be fixed by ______. (A)oxaloacetate (B) phosphoenolpyruvate (C) malate (D)pyruvate (E)acetyl CoA

20. About the nutrient translocation (source-sink) during photosynthesis, which one of the following is the best answer? (A)Mesophyll cells can transport the sugar into phloem by passive transport. (B) Junior leaf is considered as a source tissue. (C) Companion cell can provide ATP to facilitate the phloem sugars transport into sink tissue. (D)The concentration of sugar in photosynthetic mesophyll cells is lower than phloem. (E)The concentration of sugar in the apical meristem is higher than phloem.

22. Polysaccharide _____ is an important ECM component for the exoskeleton of many insects and shellfish. (A)collagen (B) laminin (C) proteoglycan (D)chitin (E)glycosaminoglycans

23. The heart is a(n) ________ composed mainly of ________ tissue? (A)tissue, endothelial (B) tissue, connective (C) organ, muscle (D)organ, connective (E)organ, epithelial

24. Which one of the following proteins is involved in synthesizing messenger RNA in eukaryotes? (A)DNA polymerase I (B) DNA polymerase II (C) DNA polymerase III (D)RNA polymerase I (E)RNA polymerase II

25. Which one of the following is the best characteristic of microRNAs (miRNAs)? (A)MicroRNAs are short RNA molecules that encoded by genome. (B) MicroRNAs can target the genome to suppress gene expression. (C) MicroRNAs can edit the RNA sequence. (D)MicroRNAs can edit DNA sequence. (E)MicroRNAs can edit amino acid sequence of protein.

26. Bacteria are grown in isotopic 15N (heavy) medium and then transferred to 14N (light) medium and allowed to replicate for 2 generations. The DNA is subsequently isolated and centrifuged in a CsCl2 gradient to yield what type of gradient band(s)? (A)One heavy and one half-heavy band. (B) One light and one half-heavy band. (C) One half-heavy (intermediate to heavy and light) band. (D)One heavy band. (E)One light band.

27. Where would one expect to find the most abundant/active telomerase? (A)Male germ cells that give rise to gametes. (B) A nerve cell from a 2-year-old individual. (C) A nerve cell from a 40-year-old individual. (D)Skin cells from a 2-year-old individual. (E)Skin cells from a 60-year-old individual.