18. If you want to reduce the chance that plants you ship will suffer from shipping damage. You should apply _________to the plants before shipping.
(A) cytokinins
(B) abscisic acid
(C) oligosaccharins
(D) gibberellins
(E) ethylene

14. Consider a living plant cell in a living leaf that has a higher water potential than the fluids surrounding the cell. In such a situation there should be________. (A) a net flow of water out of the cell (B) a net flow of water into the cell (C) no net flow of water into or out of the cell (D) gain of water by the cell only if the cell's pressure potential is high enough (E) gain of water by the cell only if the ceil's pressure potential is low enough

15. The male gametophyte in flowering plants forms in a________. (A) corolla (B) receptacle (C) stamen (D) calyx (E) carpel

16. For a typical flowering plant, the first cell of the triploid (3n) endosperm is formed from_______. (A) one sperm fused with two antipodal cells (B) two sperm fused with the egg (C) one sperm fused with the synergid (D) two sperm fused with a synergid (E) one sperm fused with the endosperm mother cell

17. The plant hormone_________ is primarily responsible for the bending of a plant shoot toward light. (A) auxin (B) ethylene (C) systemin (D) salicylic acid (E) brassinosteroid

19. In an animal in which the diploid number of chromosomes per cell is 24, what is the total number of chromatids present per cell in prophase I| after the first division and cytokinesis? (A) 6 (B) 12 (C) 24 (D) 48 (E) 96

20. A cross is performed between parents with genotypes xxYyZz and xxYyzz. What is the probability that the offspring will have the same genotype as the first parent? Capital letters indicate dominant alleles and lower case letters indicate recessive alleles. (A) 1/8 (B) 1/4 (C) 3/8 (D) 3/16 (E) 9/16

複選題21. During the elongation stage of transcription________. (A) DNA'nucleotides are added to the transcript (B) the transcript grows in the 5' to 3' direction (C) transcription factors recruit RNA polymerase to the template strand (D) the double helix remains single-stranded after being used as a template (E) RNA polymerase binds to the promoter region

22. The poly( A ) tail of an mRNA________. (A) is where the start codon is located (B) is where ribosomes attach at the start of translation (C) covers the stop codon until it is needed (D) is where translation terminates (E) protects the mRNA from attack by RNA-digesting enzymes

23. Insertion of two bases into the coding region of a gene just after the start codon of a gene will mutation. result in a_______mutation. (A) missense (B) chromosomal (C) frameshift (D) silent (E) nonsense

24. In eukaryotic cells,_________. (A) gene expression is regulated mostly at the level of transcription (B) all mRNAs tend to remain stable for about the same length of time (C) mRNA activity is altered through modifications such as phosphorylation (D) promoters are typically "on" in the absence of regulatory proteins (E) genes involved in similar processes are clustered together in operons