课程名称︰普通生物学乙上 课程性质︰必修 课程教师︰陈俊宏 开课学院：医学院 开课系所︰医学系 考试日期（年月日）︰2007／10／25 考试时限（分钟）：110min 是否需发放奖励金：是 （如未明确表示，则不予发放） 46. All of the following occur during prophase of mitosis in animal cells except A. the centrioles move toward opposite poles. B. chromosomes are duplicated. C. the nucleolus can no longer be seen. D. the nuclear envelope disappears. E. the spindle is organized. 47. What causes the decrease in the amount of cyclin at a specific point in the cell cycle? A. the binding of PDGF to receptors on the cell surface. B. its destruction by a process initiated by the activity of MPF complexes. C. the changing ratio cytoplasm to genome. D. an increase in production once the restriction point is passed. E. the cascade of increased production once its protein is phosphorylated by Cdk. 48. An enzyme that attches a phosphate group to another molecule is called a A. phosphatase. B. kinase. C. cyclase. D. phosphorylase. E. ATPase. 49. Which of the following is (are) true concerning cyclin-dependent kinase (Cdk) ? A. Cdk is inactive, or "turned off," in the presence of cyclin. B. Cdk is present throughout the cell cycle. C. Cdk is an enzyme that attaches phosphate froups to other proteins. D. Both A and B are true. E. Both B and C are true. 50. Which of the following does not occur during mitosis? A. sparation of sister chromatids. B. spindle formation. C. replication of the DNA. D. condensation of the chromosomes. E. separation of the centrosomes. 51. Which of the following statements does not apply to the Watson and Crick model of DNA? A. The distance between the strands of the helix is uniform. B. The framework of the helix consists of sugar-phosphate units of the nucleotides. C. The two strands of the helix are held together by covalent bonds. D. The purines form hydrogen bonds with pyrimidines. 52. The strands that make up NDA are antiparallel. This means that A. the twisting nature of DNA creates nonparallel strands. B. the 5' to 3' direction of one strand runs counter to the 5' to 3' direction of the other strand. C. base pairings create unequal spacing between the two DNA strands. D. one strand contains only purines and the other contains only pyrimidines. 53. Whinch enzyme catalyzes the elongation of a DNA strand in the 5' → 3' direction? A. DNA ligase. B. DNA polymerase. C. topoisomerase. D. helicase. 54. The difference between ATP and the nucleoside triphosphates used during DNA synthesis is that A. the nucleoside triphosphates have the sugar deoxyribose; ATP has the sugar ribose. B. the nucleoside triphosphates have two phosphate groups; ATP has three phosphate groups. C. ATP contains three high-energy bonds; the nucleoside triphosphates have two. D. triphosphate monomers are active in the nucleoside triphosphate, but not in ATP. 55. A new DNA strand elongates only in the 5' to 3' direction because A. DNA polymerase begins adding nucleotides at the end of the template. B. Okazaki fragments prevent elongation in the 3' to 5' direction. C. the polarity of the DNA molecule prevents addition of nucleotides at the 3' end. D. DNA polymerase can only add nucleotides to the free 3' ebd, 56. What is the role of DNA ligase in the elongation of the lagging strand during DNA replication? A. synthesize RNA nucleotides to make a primer. B. join Okazaki fragments together. C. unwind the parental double helix. D. stabilized the unwound parental DNA. 57. Individuals with the disorder xeroderma pigmentosum are hypersensitive to sunlight because their cells have an impaired ability to A. replicate DNA. B. undergo mitosis. C. repair thymine dimmers. D. recombine homologous chromosomes during meiosis. 58. After DNA replication is completed, A. each new DNA double helix consists of one old DNA strand and one new DNA strand. B. each new DNA double helix consists of new strands. C. one DNA double helix consists of two old strands and one DNA double helix consists of two new strands. D. each of the four DNA strands consists of some old strand parts and some new strand parts. 59. What is the basis for the difference in how the leading and lagging strands strands of DNA molecules are synthesized? A. The origins of replication occur only at the 5' end. B. Helicases and single-strand binding proteins work at the 5' end. C. DNA polymerase can join new nucleotides only to the 3' end of a growing strand. D. DNA ligase works only in the 3' → 5' direction. 60. Synthesis of a new DNA strand usually begins with A. an RNA primer. B. a DNA primer. C. a Okazaki fragment. D. DNA ligase. 61. A eukaryotic cell lacking active telomerase would A. be unable to take up DNA from the surrounding solution. B. be unable to identify and correct mismatched nucleotides. C. experience a gradual reduction of chromosome length with each replication cycle. D. have a greater potential to become cancerous. Ⅱ. Multiple choice questions, one question with more than one answer; 1. Which of the following statements concerning the eukaryotic chromosome is FALSE? A. It is composed of DNA and protein. B. The nucleosome is the basic structural subunit. C. The genes on each chromosome are different in different cell types. D. It consists of a single linear molecule of double-stranded DNA. E. Acitve transcription occurs on euchromatin. 2. Which of the following mechanisms is (are) used to coordinately control the expression of multiple, related genes in eukaryotic cells? A. organization of the genes into a cluster for the same local chromatin structures. B. each of the genes charing the common control elements. C. organiztion of the genes into a large operon to be transcribed as a single RNA. D. each of the genes containing a common intron. E. organiztion of the genes into the same chromosome. 3. Genomic imprinting, DNA omthylation, and histone acetylation are examples of A. genetic mutation. B. chromosomal rearrangement. C. karyotype. D. epigenetic inheritance. E. translocation. 4. The phenomenon in which RNA molecules in a cell are destroyed if they have a sequence complementary to an introduced double-stranded RNA (siRNA) is called A. RNA interference. B. RNA processing. C. RNA capping. D. RNA targeting. E. RNA splicing. 5. The activity of protein A is urgently requied in response to a specific situation in cells, but the duration for the requirement of protein A is usually very short and the presence of protein activity is harmful to cells under normal condition. Which of the following is most likely to be the regulation mechanism for protein A activity. A. changes in chromatin structure of gene A. B. initiation of transcription of gene A. C. DNA methylation on gene A. D. reversible chemical modification on protein A. E. altenative splicing of mRNA transcribed from gene A. 6. Tumor suppressor genes A. are frequently overexpressed in cancer cells. B. are cancer-causing genes introduced into cells by viruses. C. can encode proteins that promote DNA-repair or inhibit cell division. D. encode proteins that stimulate cell cycle. E. may cause cancer when dominant mutations encoding hyperactive proteins occur. 7. The incidence of cancer increase with age because A. the Ras protein is more active after age sixty. B. proteosomes become more active with age. C. telomerase becomes more active with age. D. the longer we live, the more mutations accumulate. E. tumor suppressor proteins are less active with age. 8. A genetic test to detect predisposition to cancer would likely examin the APC gene for __________ cancer and the BRCA1 and BRCA2 genes for __________ cancer. A. colorectal ; breast. B. lung ; breast. C. breast ; lung. D. colorectal ; lung. E. lung ; prostate. 9. α-globins and β-globins are classic examples of which type of DNA? A. transposons. B. simple sequence DNA. C. multigene family. D. methylated DNA. E. proto-oncogene. 10. Two eukaryotic proteins have only one domain in common but otherwise very different. Which of the following processes is most likely to have contributed to this phenomenon? A. gene duplication. B. RNA splicing. C. exon shuffling. D. histone modification. E. random point mutations. Ⅲ. 试比较真核生物与原核生物转录过程中讯号之差异 --

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