21. Protists are   not   monophyletic. This means that protists
(A) are not all members of the same phylum
(B)are all more closely related to each other than they are to any other kind of organisms
(C) are not all more closely related to each other than they are to some other organisms
(D) are all more closely related to bacteria than they are to other organisms

17. Which of the following is the first event to take place in translation in eukaryotes? (A) Base pairing of activated methionine-tRNA to AUG of the messenger RNA (B)Covalent bonding between the first two amino acids (C) The small subunit of the ribosome recognizes and attaches to the 5' cap of mRNA (D) Binding of the larger ribosomal subunit to smaller ribosomal subunits

複選題18. Which of the following statements is true? (A) As part of the transcriptional unit, regulatory sequences are the sites where RNA polymerase and transcription factors bind to regulate transcription. (B)All enzymes are proteins. (C) tRNA contains the genetic code for producing a polypeptide. (D) The termination of translation occurs when a release factor recognizes the stop codon. (E)A single gene always encodes an enzyme.

19. MicroRNAs (miRNAs) (A) are long RNA molecules. (B)silence the expression of specific mRNAs. (C) are found only in animals. (D) are cut by an enzyme called transcriptase. (E)inhibit the catalytic activity of rRNA

20. Which of the following characters is not unique to Metazoa? (A) Multicellularity (B)Having a nervous system (C) An extracellular matrix made up by collagen (D) Movement by muscle

22. Which of the following statements is not true of the stomata on the leaves of vascular plants? (A) They regulate intake of carbon dioxide needed for photosynthesis. (B)They regulate release of oxygen to the air. (C) They regulate loss of water. (D) They regulate the absorption of light by chlorophyll.

23. Picea glauca is a seed-bearing plant. What other characteristic must be true of this species? (A) It produces flowers. (B)It produces fruits. (C) It has vascular tissue. (D) The gametophyte is the dominant generation. (E)Double-fertilization results in the production of endosperm.

複選題24. Which of the following is true? (A) Viruses usually enter host cells by endocytosis. (B)Some viruses can carry out reverse transcription. (C) Viral envelope is produced from the viral genome at the later stage of infection. (D) Viruses all contain small genomes containing fewer than 100 genes.

25. Which structure is correctly paired with its tissue system? (A) root hair - vascular tissue (B)guard cell - vascular tissue (C) tracheid - vascular tissue (D) companion cell - ground tissue

26. In most plants, phloem transports _____ from the _____ (source) to the __________ (sink) in the late spring. (A) amino acids； root； mycorrhizae (B)sugars； leaf； apical meristem (C) proteins； root； leaf (D) sugars； woody stem； root

27. Phytochromes are   not   involved in _____. (A) shade avoidance (B)biological clocks (C) control of vernalization (D) gravitropism