Test File to accompany Life: The Science of Biology, Ninth Edition Sadava • Hillis • Heller • Berenbaum

Chapter 11: The Cell Cycle and Cell Division

TEST FILE QUESTIONS (By Catherine Ueckert)

Multiple Choice

1. Which of the following is not true about cervical cancer, which is a relatively common cancer? a. It can be detected early by a PAP test. b. It is usually caused by human papillomavirus (HPV). c. It causes the cervical cells to make peptide E7, which disrupts the cell cycle. d. It spreads by blocking the retinoblastoma protein RB. e. It usually remains localized. Answer: e Textbook Reference: 11.0 An enemy of the cell reproduction cycle Page: 209–210 Bloom’s Category: 1. Remembering

2. A bacterial cell gives rise to two genetically identical daughter cells by a process known as a. nondisjunction. b. mitosis. c. meiosis. d. fission. e. fertilization. Answer: d Textbook Reference: 11.1 How Do Prokaryotic and Eukaryotic Cells Divide? Page: 210 Bloom’s Category: 1. Remembering

3. For a prokaryote cell to divide, which of the following must occur? a. A reproductive signal, replication, segregation of DNA, and cytokinesis b. DNA replication, crossing over, and segregation of DNA c. DNA replication and segregation of DNA d. Cell growth and cytokinesis e. DNA replication, segregation of DNA, and cytokinesis Answer: a Textbook Reference: 11.1 How Do Prokaryotic and Eukaryotic Cells Divide? Page: 210 Bloom’s Category: 2. Understanding

4. During the bacterial cell division, the single cells is separated into two cells by a. centrosomes. b. spindle fibers. c. nucleosomes. d. pinching of the plasma membrane. e. aneuploidy. Answer: d Textbook Reference: 11.1 How Do Prokaryotic and Eukaryotic Cells Divide? Page: 211 Bloom’s Category: 2. Understanding

5. During prokaryotic cell division, two chromosomes separate from each other and distribute into the daughter cells by a. attachment to microtubules. b. a mitotic spindle. c. repellent forces. d. attachment to separating membrane regions. e. All of the above Answer: d Textbook Reference: 11.1 How Do Prokaryotic and Eukaryotic Cells Divide? Page: 211 Bloom’s Category: 2. Understanding

6. Bacteria typically have ______, whereas eukaryotes have ______. a. one chromosome that is circular; many chromosomes that are linear b. several chromosomes that are circular; many chromosomes that are linear c. one chromosome that is linear; many chromosomes that are circular d. two chromosomes that are circular; eight chromosomes that are linear e. None of the above Answer: a Textbook Reference: 11.1 How Do Prokaryotic and Eukaryotic Cells Divide? Page: 211 Bloom’s Category: 2. Understanding

7. Which of the following statements about mitosis is true? a. The chromosome number in the resulting cells is halved. b. DNA replication is completed in prophase. c. Crossing over occurs during prophase. d. Two genetically identical daughter cells are formed. e. It consists of two nuclear divisions. Answer: d Textbook Reference: 11.1 How Do Prokaryotic and Eukaryotic Cells Divide? Page: 212 Bloom’s Category: 2. Understanding

8. DNA replication occurs a. during both mitosis and meiosis. b. only during mitosis. c. only during meiosis. d. during the S phase. e. during G2. Answer: d Textbook Reference: 11.2 How Is Eukaryotic Cell Division Controlled? Page: 213 Bloom’s Category: 1. Remembering

9. Mature nerve cells, which are incapable of cell division, are most likely in a. G1. b. the S phase. c. G2. d. mitosis. e. meiosis. Answer: a Textbook Reference: 11.2 How Is Eukaryotic Cell Division Controlled? Page: 213 Bloom’s Category: 3. Applying

10. A set of cells in the intestinal epithelium divide continually to replace dead cells lost from the surface of the intestinal lining. If you examined this continually dividing population of intestinal epithelial cells under the microscope, most of the cells would a. be in meiosis. b. be in mitosis. c. be in interphase. d. have condensed chromatin. e. Both b and d Answer: c Textbook Reference: 11.2 How Is Eukaryotic Cell Division Controlled? Page: 213 Bloom’s Category: 3. Applying

11. Cells that do not divide are usually arrested in a. S. b. G1. c. G2. d. M. e. prophase. Answer: b Textbook Reference: 11.2 How Is Eukaryotic Cell Division Controlled? Page: 213 Bloom’s Category: 1. Remembering

12. Which of the following phases of the cell cycle is not part of interphase? a. M b. S c. G1 d. G2 e. G0 Answer: a Textbook Reference: 11.2 How Is Eukaryotic Cell Division Controlled? Page: 213 Bloom’s Category: 1. Remembering

13. How does a nucleus in G2 differ from a nucleus in G1? a. The G2 nucleus has double the amount of DNA as the G1 nucleus. b. DNA synthesis occurs only in the G1 phase. c. Inactive cells are arrested only in the G2 phase. d. During G2, the cell prepares for S phase. e. All of the above Answer: a Textbook Reference: 11.2 How Is Eukaryotic Cell Division Controlled? Page: 213 Bloom’s Category: 2. Understanding

14. A typical cell cycle consists of a. mitosis and meiosis. b. G1, the S phase, and G2. c. prophase, metaphase, anaphase, and telophase. d. interphase, mitosis, and cytokinesis. e. meiosis and fertilization. Answer: d Textbook Reference: 11.2 How Is Eukaryotic Cell Division Controlled? Page: 213 Bloom’s Category: 1. Remembering

15. Regulation of the cell cycle is dependent on cyclins and cyclin-dependent kinases. The key(s) that allows a cell to progress beyond the restriction point is (are) a. Cdk1 and cyclin B. b. cyclin D and p21. c. cyclin A and Cdk2. d. phosphorylation of RB by Cdk4 and Cdk2. e. external signals from growth factors. Answer: d Textbook Reference: 11.2 How Is Eukaryotic Cell Division Controlled? Page: 214 Bloom’s Category: 2. Understanding 16. Evidence from yeast suggests that the maturation-promoting factor of sea urchins is a. a cyclin. b. MFP. c. an S nuclease. d. a Cdk. e. a Cdk/cyclin phosphatase. Answer: d Textbook Reference: 11.2 How Is Eukaryotic Cell Division Controlled? Page: 214 Bloom’s Category: 1. Remembering

17. The initiation of the S phase and the M phase of the cell cycle depends on a pair of molecules called ______and ______. a. actin; myosin b. Cdk’s; cyclin c. ligand; receptor d. MSH; MSH-receptor e. ATP; ATPase Answer: b Textbook Reference: 11.2 How Is Eukaryotic Cell Division Controlled? Page: 214 Bloom’s Category: 1. Remembering

18. When cyclin binds Cdk, a. the cell transitions from G2 to S. b. kinase activation occurs. c. chromosomes condense. d. the cell quickly enters M phase. e. the cell begins apoptosis. Answer: b Textbook Reference: 11.2 How Is Eukaryotic Cell Division Controlled? Page: 214 Bloom’s Category: 2. Understanding

19. Cyclin-dependent kinases (Cdk’s) catalyze the phosphorylation of targeted proteins, a process that a. decreases the mass of the protein. b. makes the targeted proteins hydrophobic. c. changes the shape and function of the targeted proteins. d. gives the proteins a three-dimensional shape. e. blocks the cell cycle from proceeding. Answer: c Textbook Reference: 11.2 How Is Eukaryotic Cell Division Controlled? Page: 214 Bloom’s Category: 2. Understanding 20. DNA damage by UV radiation causes the synthesis of a. p53. b. DNA. c. Cdk. d. cyclin. e. p21. Answer: e Textbook Reference: 11.2 How Is Eukaryotic Cell Division Controlled? Page: 215 Bloom’s Category: 1. Remembering

21. Interleukins and erythropoietin are a. growth factors. b. Cdk’s. c. cyclins. d. antitumor agents. e. intracellular signaling molecules. Answer: a Textbook Reference: 11.2 How Is Eukaryotic Cell Division Controlled? Page: 215 Bloom’s Category: 1. Remembering

22. The DNA of a eukaryotic cell is a. double-stranded. b. single-stranded. c. circular. d. complex inverted. e. conservative. Answer: a Textbook Reference: 11.3 What Happens during Mitosis? Page: 215 Bloom’s Category: 1. Remembering

23. The uncondensed length of human DNA found in chromosomes is ______, whereas a typical cell is 10 µm in length. a. 5 µm b. 2 µm c. 2 meters d. 20 meters e. 2.54 inches Answer: c Textbook Reference: 11.3 What Happens during Mitosis? Page: 216 Bloom’s Category: 1. Remembering 24. Chromosomes contain large amounts of interacting proteins known as a. pentanes. b. hexosamines. c. histones. d. protein hormones. e. histamines. Answer: c Textbook Reference: 11.3 What Happens during Mitosis? Page: 216 Bloom’s Category: 1. Remembering

25. The molecules that make up a chromosome are ______and ______. a. DNA; RNA b. DNA; proteins c. proteins; lipids d. nucleotides; nucleosides e. proteins; phospholipids Answer: b Textbook Reference: 11.3 What Happens during Mitosis? Page: 216 Bloom’s Category: 2. Understanding

26. The basic structure of chromatin has sometimes been referred to as beads on a string of DNA. These beads are called a. chromosomes. b. chromatids. c. supercoils. d. interphases. e. nucleosomes. Answer: e Textbook Reference: 11.3 What Happens during Mitosis? Page: 216 Bloom’s Category: 2. Understanding

27. Chromatin consists of a. DNA and histones. b. DNA, histones, and many other nonhistone proteins. c. mostly RNA and DNA. d. RNA, DNA, and nonhistone proteins. e. DNA only. Answer: b Textbook Reference: 11.3 What Happens during Mitosis? Page: 216 Bloom’s Category: 1. Remembering

28. Nucleosomes contain ______and ______. a. centromeres; DNA b. microtubules; condensins c. kinetochores; centromeres d. histones; DNA e. polar microtubules; kinetochore microtubules Answer: d Textbook Reference: 11.3 What Happens during Mitosis? Page: 216 Bloom’s Category: 1. Remembering

29. During mitosis and meiosis the chromatin compacts. Which of the following processes takes place more easily because of this compaction? a. The orderly distribution of genetic material to two new nuclei b. The replication of the DNA c. Exposing the genetic information on the DNA d. The unwinding of DNA from around the histones e. The disappearance of the nuclear membrane Answer: a Textbook Reference: 11.3 What Happens during Mitosis? Page: 216 Bloom’s Category: 2. Understanding

30. The products of mitosis are a. one nucleus containing twice as much DNA as the parent nucleus. b. two genetically identical cells. c. four nuclei containing half as much DNA as the parent nucleus. d. four genetically identical nuclei. e. two genetically identical nuclei. Answer: e Textbook Reference: 11.3 What Happens during Mitosis? Page: 216 Bloom’s Category: 2. Understanding

31. The mitotic spindle is composed of a. chromosomes. b. chromatids. c. microtubules. d. chromatin. e. centrosomes. Answer: c Textbook Reference: 11.3 What Happens during Mitosis? Page: 216 Bloom’s Category: 1. Remembering

32. Centrosomes a. are constricted regions of phase chromosomes. b. determine the plane of cell division. c. are the central region of the cell. d. are the region where the membrane constricts during cytokinesis. e. are part of cilia. Answer: b Textbook Reference: 11.3 What Happens during Mitosis? Page: 216 Bloom’s Category: 1. Remembering

33. When dividing cells are examined under a light microscope, chromosomes first become visible during a. interphase. b. the S phase. c. prophase. d. G1. e. G2. Answer: c Textbook Reference: 11.3 What Happens during Mitosis? Page: 216 Bloom’s Category: 1. Remembering

34. Chromatin condenses to form discrete, visible chromosomes a. early in G1. b. during S. c. during telophase. d. during prophase. e. at the end of cytokinesis. Answer: d Textbook Reference: 11.3 What Happens during Mitosis? Page: 216 Bloom’s Category: 1. Remembering

35. Microtubules that form the mitotic spindle tend to originate from or terminate in a. centromeres and telomeres. b. euchromatin. c. centrioles and telomeres. d. the nuclear envelope. e. centrioles and kinetochores. Answer: e Textbook Reference: 11.3 What Happens during Mitosis? Page: 216–217 Bloom’s Category: 2. Understanding

36. Which of the following does not occur during mitotic prometaphase? a. Disappearance of the nuclear envelope b. Initial movement of chromosomes toward the equatorial plate c. Adhesion of chromatids at the centromere d. Synapsis of homologous chromosomes e. Disappearance of the nuclei Answer: d Textbook Reference: 11.3 What Happens during Mitosis? Page: 216–219 Bloom’s Category: 2. Understanding

37. The structures that line up the chromatids on the equatorial plate during metaphase are called a. asters. b. polar and kinetochore microtubules. c. centrosomes. d. centrioles. e. histones. Answer: b Textbook Reference: 11.3 What Happens during Mitosis? Page: 217 Bloom’s Category: 1. Remembering

38. The microtubules of the mitotic spindle attach to a specialized structure in the centromere region of each chromosome called the a. kinetochore. b. nucleosome. c. equatorial plate. d. aster. e. centrosome. Answer: a Textbook Reference: 11.3 What Happens during Mitosis? Page: 217 Bloom’s Category: 1. Remembering

39. During mitotic anaphase, chromosomes migrate a. from the poles of the cell toward the equatorial plate. b. from the equatorial plate toward the poles. c. toward the nuclear envelope. d. along with their sister chromatids toward one pole. e. along with the other member of the homologous pair toward the equatorial plate. Answer: b Textbook Reference: 11.3 What Happens during Mitosis? Page: 219 Bloom’s Category: 1. Remembering

40. At the milestone that defines metaphase, the chromosomes a. separate. b. come together. c. are at opposite poles. d. line up at the equatorial plate. e. cross over. Answer: d Textbook Reference: 11.3 What Happens during Mitosis? Page: 219 Bloom’s Category: 1. Remembering

41. At the milestone that defines anaphase, the chromosomes a. separate. b. come together. c. are at opposite poles. d. line up. e. cross over. Answer: a Textbook Reference: 11.3 What Happens during Mitosis? Page: 219 Bloom’s Category: 1. Remembering

42. The energy to move chromosomes during mitosis is provided by a. centrioles. b. DNA polymerization. c. migration of the centrosomes. d. formation of the cell plate. e. ATP. Answer: e Textbook Reference: 11.3 What Happens during Mitosis? Page: 219 Bloom’s Category: 1. Remembering

43. Which of the following is not involved in the separation of paired chromatids and their movement to opposite poles? a. Sister chromatids attach to microtubules in opposite halves of the spindle. b. Separase hydrolyzes cohesion, allowing chromatid separation. c. Tubulin fibers move the chromatids away from the equatorial plate. d. Polar microtubules push the chromatids to the poles. e. ATP is hydrolyzed by cytoplasmic dynein. Answer: d Textbook Reference: 11.3 What Happens during Mitosis? Page: 219 Bloom’s Category: 2. Understanding

44. At the milestone that defines telophase, the chromosomes a. separate. b. come together. c. are at opposite poles. d. line up. e. cross over. Answer: c Textbook Reference: 11.3 What Happens during Mitosis? Page: 219 Bloom’s Category: 1. Remembering

45. Chromosomes “decondense” into diffuse chromatin a. at the end of telophase. b. at the beginning of prophase. c. at the end of interphase. d. at the end of metaphase. e. only in dying cells. Answer: a Textbook Reference: 11.3 What Happens during Mitosis? Page: 219 Bloom’s Category: 1. Remembering

46. After the centromeres separate during mitosis, the chromatids, now called ______, move toward opposite poles of the spindle. a. centrosomes b. kinetochores c. half-spindles d. asters e. daughter chromosomes Answer: e Textbook Reference: 11.3 What Happens during Mitosis? Page: 220 Bloom’s Category: 2. Understanding

47. In plant cells, cytokinesis is accomplished by the formation of a(n) a. aster. b. membrane furrow. c. equatorial plate. d. cell plate. e. spindle. Answer: d Textbook Reference: 11.3 What Happens during Mitosis? Page: 220 Bloom’s Category: 1. Remembering

48. The event in the cell division process that clearly involves microfilaments is a. chromosome separation during anaphase. b. movement of chromosomes to the metaphase plate. c. chromosome condensation during prophase. d. disappearance of the nuclear envelope during prophase. e. cytokinesis in animal cells. Answer: e Textbook Reference: 11.3 What Happens during Mitosis? Page: 220 Bloom’s Category: 2. Understanding

49. Which of the following statements about plant cytokinesis is true? a. It begins when telophase ends. b. A division furrow completely separates the cytoplasm. c. It is under the control of Ca2+. d. Vesicles fuse to form a cell plate. e. The spindle fibers break down to form a cell plate. Answer: d Textbook Reference: 11.3 What Happens during Mitosis? Page: 220 Bloom’s Category: 2. Understanding

50. The distribution of mitochondria between the daughter cells during cytokinesis a. is random. b. is directed by the mitotic spindle. c. is directed by the centrioles. d. results in the mitochondria remaining in the parent cell. e. occurs only during meiosis. Answer: a Textbook Reference: 11.3 What Happens during Mitosis? Page: 220 Bloom’s Category: 2. Understanding

51. A mechanism for increasing the genetic diversity of offspring is a. mitosis. b. cloning. c. sexual reproduction. d. cytokinesis. e. fission. Answer: c Textbook Reference: 11.4 What Role Does Cell Division Play in a Sexual Life Cycle? Page: 221 Bloom’s Category: 2. Understanding

52. The major drawback of asexual reproduction is that it a. takes a great deal of time. b. generates variation. c. prevents change. d. requires cytokinesis. e. produces less variation among offspring than does sexual reproduction. Answer: e Textbook Reference: 11.4 What Role Does Cell Division Play in a Sexual Life Cycle? Page: 221 Bloom’s Category: 2. Understanding

53. During asexual reproduction, the genetic material of the parent is passed on to the offspring by a. homologous pairing. b. meiosis and fertilization. c. mitosis and cytokinesis. d. karyotyping. e. chiasmata. Answer: c Textbook Reference: 11.4 What Role Does Cell Division Play in a Sexual Life Cycle? Page: 221 Bloom’s Category: 2. Understanding

54. A haploid cell is a cell a. in which the genes are arranged haphazardly. b. containing only one copy of each chromosome. c. that has resulted from the process of mitosis. d. with twice the number of chromosomes of a diploid cell. e. None of the above Answer: b Textbook Reference: 11.4 What Role Does Cell Division Play in a Sexual Life Cycle? Page: 222 Bloom’s Category: 2. Understanding

55. All zygotes are a. multicellular. b. diploid. c. animals. d. clones. e. gametes. Answer: b Textbook Reference: 11.4 What Role Does Cell Division Play in a Sexual Life Cycle? Page: 222 Bloom’s Category: 2. Understanding

56. In all sexually reproducing organisms, the diploid phase of the life cycle begins at a. spore formation. b. gamete formation. c. meiosis. d. mitosis. e. fertilization. Answer: e Textbook Reference: 11.4 What Role Does Cell Division Play in a Sexual Life Cycle? Page: 222 Bloom’s Category: 2. Understanding

57. The members of a homologous pair of chromosomes a. are identical in size and appearance. b. contain identical genetic information. c. separate to opposite poles of the cell during mitosis. d. are found only in haploid cells. e. are present only after the S phase. Answer: a Textbook Reference: 11.4 What Role Does Cell Division Play in a Sexual Life Cycle? Page: 222 Bloom’s Category: 1. Remembering

58. Asexual reproduction produces genetically identical individuals because a. chromosomes do not have to replicate during asexual reproduction. b. it involves chromosome replication without cytokinesis. c. no meiosis or fertilization take place. d. cell division occurs only in meiosis. e. the mitotic spindle prevents nondisjunction. Answer: c Textbook Reference: 11.4 What Role Does Cell Division Play in a Sexual Life Cycle? Page: 222 Bloom’s Category: 2. Understanding

59. Each diploid cell of a human female contains ______of each type of chromosome. a. one b. two c. four d. a total of 23 e. a total of 46 Answer: b Textbook Reference: 11.4 What Role Does Cell Division Play in a Sexual Life Cycle? Page: 222 Bloom’s Category: 2. Understanding

60. Sexual reproduction increases genetic variability through a. the exchange of genetic information between male and female gametes during meiosis I. b. the random separation of homologous chromosomes. c. the union of male and female gametes. d. crossing over, independent assortment, and random fertilization. e. random assortment of male and female chromosomes. Answer: d Textbook Reference: 11.4 What Role Does Cell Division Play in a Sexual Life Cycle? Page: 223 Bloom’s Category: 2. Understanding

61. In a haploid organism, most mitosis occurs a. after fertilization and before meiosis. b. after meiosis and before fertilization. c. between meiosis I and II. d. during G1. e. in diploid cells. Answer: b Textbook Reference: 11.4 What Role Does Cell Division Play in a Sexual Life Cycle? Page: 223 Bloom’s Category: 2. Understanding

62. The sizes and shapes of chromosomes can be observed most easily in a cell that is in a. prophase. b. metaphase. c. anaphase. d. telophase. e. cytokinesis. Answer: b Textbook Reference: 11.4 What Role Does Cell Division Play in a Sexual Life Cycle? Page: 223 Bloom’s Category: 1. Remembering

63. The diagnosis of Down syndrome is made by examining the individual’s a. spores. b. karyotype. c. chromatin. d. nucleosomes. e. kinetochores. Answer: b Textbook Reference: 11.4 What Role Does Cell Division Play in a Sexual Life Cycle? Page: 223 Bloom’s Category: 2. Understanding

64. Human males have ______sex chromosomes. a. XX b. XY c. XO d. three types of e. 23 Answer: b Textbook Reference: 11.4 What Role Does Cell Division Play in a Sexual Life Cycle? Page: 223 Bloom’s Category: 1. Remembering 65. Diploid cells of the fruit fly Drosophila have ten chromosomes. How many chromosomes does a Drosophila gamete have? a. 1 b. 2 c. 5 d. 10 e. 20 Answer: c Textbook Reference: 11.5 What Happens during Meiosis? Page: 224–225 Bloom’s Category: 2. Understanding

66. The second meiotic division of meiosis is important because a. it returns the chromosome number to diploid before fertilization. b. it allows for crossing over and random distribution of chromosomes. c. it reduces cell size by dividing the cytoplasm in half. d. without this division, chromosome copies would double at each fertilization. e. fertilization requires this step. Answer: d Textbook Reference: 11.5 What Happens during Meiosis? Page: 225 Bloom’s Category: 4. Analyzing

67. Meiosis can occur a. in all sexually reproducing organisms. b. only when an organism is diploid. c. only in multicellular organisms. d. only in haploid organisms. e. only in single-celled organisms. Answer: a Textbook Reference: 11.5 What Happens during Meiosis? Page: 225 Bloom’s Category: 2. Understanding

68. Which of the following is not part of sexual reproduction? a. The segregation of homologous chromosomes during gamete formation b. The fusion of sister chromatids during fertilization c. The fusion of haploid cells from a diploid zygote d. The reduction in chromosome number during meiosis e. The production of genetically distinct gametes during meiosis Answer: b Textbook Reference: 11.5 What Happens during Meiosis? Page: 226 Bloom’s Category: 2. Understanding

69. Which of the following statements about homologous chromosome pairs is false? a. They come from only one of the individual’s parents. b. They usually contain slightly different versions of the same genetic information. c. They separate from each other during meiosis I. d. They synapse during meiosis I. e. Each contains two sister chromatids at the beginning of meiosis I. Answer: a Textbook Reference: 11.5 What Happens during Meiosis? Page: 226 Bloom’s Category: 2. Understanding

70. During meiosis, the sister chromatids separate during a. anaphase II. b. anaphase I. c. the S phase. d. synapsis. e. telophase II. Answer: a Textbook Reference: 11.5 What Happens during Meiosis? Page: 226 Bloom’s Category: 1. Remembering

71. At the end of the first meiotic division, each chromosome consists of a. chiasmata. b. a homologous chromosome pair. c. four copies of each DNA molecule. d. two chromatids. e. a pair of polar microtubules. Answer: d Textbook Reference: 11.5 What Happens during Meiosis? Page: 226 Bloom’s Category: 2. Understanding

72. Which of the following statements about sister chromatids is false? a. They arise by replication during S phase. b. They separate from each other during each mitotic anaphase. c. They usually contain identical versions of the same genetic information. d. They separate from each other during meiosis I. e. They are joined during prophase I and metaphase I at their common centromere. Answer: d Textbook Reference: 11.5 What Happens during Meiosis? Page: 226 Bloom’s Category: 2. Understanding

73. The processes of synapsis and the formation of chiasmata a. involve reciprocal exchange of chromosomal sections. b. involve the recombination of DNA on homologous chromosomes. c. bring about an increase in genetic variation. d. provide evidence that an exchange of genetic material has occurred. e. All of the above Answer: e Textbook Reference: 11.5 What Happens during Meiosis? Page: 226 Bloom’s Category: 2. Understanding

74. The exchange of genetic material between chromatids on homologous chromosomes occurs during a. interphase. b. mitosis and meiosis. c. prophase I. d. anaphase I. e. anaphase II. Answer: c Textbook Reference: 11.5 What Happens during Meiosis? Page: 226 Bloom’s Category: 1. Remembering

75. The number of chromosomes is reduced to half during a. anaphase of mitosis and meiosis. b. meiosis II. c. meiosis I. d. fertilization. e. interphase. Answer: c Textbook Reference: 11.5 What Happens during Meiosis? Page: 226 Bloom’s Category: 1. Remembering

76. The total DNA content of each daughter cell is reduced during meiosis because a. chromosomes do not replicate during the interphase preceding meiosis I. b. chromosomes do not replicate between meiosis I and II. c. half of the chromosomes from each gamete are lost during fertilization. d. sister chromatids separate during anaphase of meiosis I. e. chromosome arms are lost during crossing over. Answer: b Textbook Reference: 11.5 What Happens during Meiosis? Page: 226 Bloom’s Category: 2. Understanding

77. Chromosome number is reduced during meiosis because the process consists of a. two cell divisions without any chromosome replication. b. a single cell division without any chromosome replication. c. two cell divisions in which half of the chromosomes are destroyed. d. two cell divisions and only a single round of chromosome replication. e. four cell divisions with no chromosome replication. Answer: d Textbook Reference: 11.5 What Happens during Meiosis? Page: 226 Bloom’s Category: 2. Understanding

78. The four haploid nuclei found at the end of meiosis differ from one another in their exact genetic composition. Some of this difference is the result of a. cytokinesis. b. replication of DNA during the S phase. c. separation of sister chromatids at anaphase II. d. spindle formation. e. crossing over during prophase I. Answer: e Textbook Reference: 11.5 What Happens during Meiosis? Page: 226 Bloom’s Category: 2. Understanding

79. During meiosis I in humans, one of the daughter cells receives a. only maternal chromosomes. b. a mixture of maternal and paternal chromosomes. c. the same number of chromosomes as that of a diploid cell. d. a sister chromatid from each chromosome. e. one-fourth the amount of DNA in the parent nucleus. Answer: b Textbook Reference: 11.5 What Happens during Meiosis? Page: 226 Bloom’s Category: 2. Understanding

80. One difference between mitosis and meiosis I is that a. homologous chromosome pairs synapse during mitosis. b. chromosomes do not replicate in the interphase preceding meiosis. c. homologous chromosome pairs synapse during meiosis but not during mitosis. d. spindles composed of microtubules are not required during meiosis. e. sister chromatids separate during meiosis but not during mitosis. Answer: c Textbook Reference: 11.5 What Happens during Meiosis? Page: 226 Bloom’s Category: 2. Understanding

81. A triploid nucleus cannot undergo meiosis because a. the DNA cannot replicate. b. not all of the chromosomes can form homologous pairs. c. the sister chromatids cannot separate. d. cytokinesis cannot occur. e. a cell plate cannot form. Answer: b Textbook Reference: 11.5 What Happens during Meiosis? Page: 226 Bloom’s Category: 2. Understanding

82. Genetic recombination occurs during a. prophase of meiosis I. b. the interphase preceding meiosis II. c. the mitotic telophase. d. fertilization. e. the formation of somatic cells. Answer: a Textbook Reference: 11.5 What Happens during Meiosis? Page: 226–228 Bloom’s Category: 1. Remembering

83. How does mitotic prophase differ from prophase I of meiosis? a. Chromatin supercoils only in mitotic prophase. b. The nuclear envelope disappears only in prophase I of meiosis. c. Synapsis occurs in mitotic prophase and but not in meiotic prophase I. d. The chromatids separate in mitotic prophase, not in prophase I of meiosis. e. Crossing over is characteristic of prophase I of meiosis but not of mitotic prophase. Answer: e Textbook Reference: 11.5 What Happens during Meiosis? Page: 228 Bloom’s Category: 4. Analyzing

84. Accidents during meiosis that can result in trisomies and monosomies are called a. nondisjunctions. b. inversions. c. reciprocal translocations. d. recombinations. e. acrocentricities. Answer: a Textbook Reference: 11.5 What Happens during Meiosis? Page: 228–229 Bloom’s Category: 1. Remembering

85. A potato has a diploid number of 48. If an egg of this plant has 23 chromosomes, the most likely explanation is that a. normal meiosis has occurred. b. nondisjunction occurred during meiosis I. c. normal mitosis has occurred. d. nondisjunction occurred during mitosis. e. crossing over occurred during meiosis I. Answer: b Textbook Reference: 11.5 What Happens during Meiosis? Page: 228–229 Bloom’s Category: 2. Understanding

86. The fact that most monosomies and trisomies are lethal to human embryos illustrates the a. importance of the orderly distribution of genetic material during meiosis. b. exchange of genetic information during crossing over. c. advantage of sexual reproduction to the survival of a population. d. fact that each chromosome contains a single molecule of DNA. e. formation of haploid gametes as a result of meiosis. Answer: a Textbook Reference: 11.5 What Happens during Meiosis? Page: 228–229 Bloom’s Category: 2. Understanding

87. A person with Klinefelter syndrome has 44 chromosomes and three sex chromosomes (XXY). The resulting aneuploidy is caused by a. nondisjunction. b. crossing over. c. a mutation. d. an enzyme deficiency. e. failure of DNA to replicate. Answer: a Textbook Reference: 11.5 What Happens during Meiosis? Page: 228–229 Bloom’s Category: 2. Understanding

88. Many chromosome abnormalities (trisomies and monosomies) are not observed in the human population because a. they are lethal and cause spontaneous abortion of the embryo early in development. b. all trisomies and monosomies are lethal early in childhood. c. meiosis distributes chromosomes to daughter cells with great precision. d. they are so difficult to count. e. the human meiotic spindle is self-correcting. Answer: a Textbook Reference: 11.5 What Happens during Meiosis? Page: 228–229 Bloom’s Category: 2. Understanding

89. A triploid plant has a. one extra chromosome. b. one extra set of chromosomes. c. three chromosomes. d. three times the chance of surviving that a monoploid has. e. None of the above Answer: b Textbook Reference: 11.5 What Happens during Meiosis? Page: 229 Bloom’s Category: 1. Remembering

90. The process of programmed cell death is called a. necrosis. b. lysis. c. apoptosis. d. cell displacement. e. cellular suicide. Answer: c Textbook Reference: 11.6 In a Living Organism, How Do Cells Die? Page: 229 Bloom’s Category: 1. Remembering

91. Which of the following statements about necrosis is true? a. It requires ATP. b. It does not cause inflammation. c. It may occur when cells are damaged by toxins. d. It produces nucleosome-sized pieces of chromatin. e. It results in fragmentation of the cell. Answer: c Textbook Reference: 11.6 In a Living Organism, How Do Cells Die? Page: 229 Bloom’s Category: 2. Understanding

92. An indicator of programmed cell death is a. fragmented chromatin. b. swelling of the membrane. c. cell lysis. d. loss of transcription control. e. All of the above Answer: a Textbook Reference: 11.6 In a Living Organism, How Do Cells Die? Page: 230 Bloom’s Category: 2. Understanding

93. Which of the following is true of benign tumors? a. The cells do not resemble the cells of the parent tissue. b. The cells of the tumor are often irregular, with nuclei of various sizes and shapes. c. The cells grow more rapidly than the cells surrounding it. d. They often metastasize. e. They are not cancer. Answer: e Textbook Reference: 11.7 How Does Unregulated Cell Division Lead to Cancer? Page: 230 Bloom’s Category: 2. Understanding

94. One-fourth of all human breast cancers have been found to have an increased amount of the oncogene a. P21. b. HER2. c. Cdk. d. Cyclin. e. RB. Answer: b Textbook Reference: 11.7 How Does Unregulated Cell Division Lead to Cancer? Page: 231 Bloom’s Category: 1. Remembering

95. Knowledge of the cell cycle has led to improved means of treating cancer. The drug 5-fluorouracil blocks the synthesis of thymine. This drugs inhibits the cell cycle at the end of a. G1. b. G2. c. S. d. prophase. e. metaphase. Answer: b Textbook Reference: 11.7 How Does Unregulated Cell Division Lead to Cancer? Page: 232 Bloom’s Category: 4. Analyzing

96. Knowledge of the cell cycle has led to improved means of treating cancer. Taxol prevents the microtubules of the spindle fiber from functioning normally. Taxol prevents the cell cycle from entering a. G1. b. G2. c. S. d. prophase. e. interphase. Answer: d Textbook Reference: 11.7 How Does Unregulated Cell Division Lead to Cancer? Page: 232 Bloom’s Category: 4. Analyzing

97. High-energy radiation is often used to treat cancer. The radiation kills the cancerous cells, and the cell cycle checkpoint for DNA repair is overwhelmed. Radiation a. causes apoptosis at the S and G2 checkpoints. b. inhibits the growth factor at the restriction point. c. blocks DNA replication. d. only causes apoptosis at the tumor site. e. kills all tumor cells without harm to healthy cells. Answer: a Textbook Reference: 11.7 How Does Unregulated Cell Division Lead to Cancer? Page: 232 Bloom’s Category: 1. Remembering

Fill in the Blank

1. The orderly distribution of genetic information occurs in prokaryotic cells by a process known as ______. Answer: binary fission Textbook Reference: 11.1 How Do Prokaryotic and Eukaryotic Cells Divide? Page: 210 Bloom’s Category: 1. Remembering

2. The heritable information of the cell is ______. Answer: DNA Textbook Reference: 11.1 How Do Prokaryotic and Eukaryotic Cells Divide? Page: 211 Bloom’s Category: 1. Remembering

3. Prokaryotic DNA molecules are packaged by ______proteins, which associate with DNA. Answer: basic Textbook Reference: 11.1 How Do Prokaryotic and Eukaryotic Cells Divide? Page: 211 Bloom’s Category: 1. Remembering

4. Bacteria have a short sequence called ______, where DNA synthesis begins. Answer: ori Textbook Reference: 11.1 How Do Prokaryotic and Eukaryotic Cells Divide? Page: 211 Bloom’s Category: 1. Remembering

5. Bacteria have a short sequence called ______, where DNA synthesis ends. Answer: ter Textbook Reference: 11.1 How Do Prokaryotic and Eukaryotic Cells Divide? Page: 211 Bloom’s Category: 1. Remembering

6. When a DNA molecule doubles, a chromosome is then made up of two joined ______. Answer: chromatids Textbook Reference: 11.1 How Do Prokaryotic and Eukaryotic Cells Divide? Page: 212 Bloom’s Category: 1. Remembering

7. The process that ensures that only one of each pair of chromosomes is included in a gamete is ______. Answer: meiosis Textbook Reference: 11.1 How Do Prokaryotic and Eukaryotic Cells Divide? Page: 212 Bloom’s Category: 2. Understanding

8. The stage of the cell cycle during which DNA replicates is called the ______. Answer: S phase Textbook Reference: 11.2 How Is Eukaryotic Cell Division Controlled? Page: 213 Bloom’s Category: 1. Remembering

9. The G2 phase always follows ______phase. Answer: S Textbook Reference: 11.2 How Is Eukaryotic Cell Division Controlled? Page: 213 Bloom’s Category: 1. Remembering

10. The G in G1 and G2 is short for “______.” Answer: gap Textbook Reference: 11.2 How Is Eukaryotic Cell Division Controlled? Page: 213 Bloom’s Category: 1. Remembering

11. To divide, cells must be stimulated by external chemical signals called ______. Answer: growth factors Textbook Reference: 11.2 How Is Eukaryotic Cell Division Controlled? Page: 215 Bloom’s Category: 1. Remembering

12. The structure that is present during mitosis and is composed of two identical DNA molecules complexed with proteins and joined at the centromere is called a ______. Answer: chromosome Textbook Reference: 11.3 What Happens during Mitosis? Page: 215 Bloom’s Category: 1. Remembering

13. During prometaphase, the chromatids are held together by ______. Answer: centromere Textbook Reference: 11.3 What Happens during Mitosis? Page: 215 Bloom’s Category: 1. Remembering 14. The chromatin ______during prophase. Answer: condenses Textbook Reference: 11.3 What Happens during Mitosis? Page: 215–216 Bloom’s Category: 1. Remembering

15. The process that ensures that genetic information is passed on to a cell’s daughter cells is ______. Answer: mitosis Textbook Reference: 11.3 What Happens during Mitosis? Page: 216 Bloom’s Category: 1. Remembering

16. The main role of nucleosomes in eukaryotic cells is to ______the DNA. Answer: package Textbook Reference: 11.3 What Happens during Mitosis? Page: 216 Bloom’s Category: 2. Understanding

17. The milestone event that defines entry into prometaphase is loss of the ______. Answer: nuclear envelope Textbook Reference: 11.3 What Happens during Mitosis? Page: 217 Bloom’s Category: 1. Remembering

18. In general, the division of the cell, called ______, follows immediately after mitosis. Answer: cytokinesis Textbook Reference: 11.3 What Happens during Mitosis? Page: 219–220 Bloom’s Category: 1. Remembering

19. In plants, a(n) ______forms at the equatorial region of the cell. Answer: cell plate Textbook Reference: 11.3 What Happens during Mitosis? Page: 220 Bloom’s Category: 1. Remembering

20. The cell plate is derived from the ______of the cell. Answer: Golgi apparatus Textbook Reference: 11.3 What Happens during Mitosis? Page: 220 Bloom’s Category: 1. Remembering

21. The “invisible thread” that pinches animal cells apart during cell division is made of ______and ______. Answer: actin; myosin Textbook Reference: 11.3 What Happens during Mitosis? Page: 220 Bloom’s Category: 1. Remembering

22. A zygote usually has ______copies of each chromosome. Answer: two Textbook Reference: 11.4 What Role Does Cell Division Play in a Sexual Life Cycle? Page: 222 Bloom’s Category: 1. Remembering

23. A(n) ______is one of a pair of chromosomes having the same overall genetic composition and sequence. Answer: homolog Textbook Reference: 11.4 What Role Does Cell Division Play in a Sexual Life Cycle? Page: 222 Bloom’s Category: 1. Remembering

24. ______is the fusion of two gametes. Answer: Fertilization Textbook Reference: 11.4 What Role Does Cell Division Play in a Sexual Life Cycle? Page: 222 Bloom’s Category: 1. Remembering

25. The ______is the number, form, and type of chromosomes found in a cell. Answer: karyotype Textbook Reference: 11.4 What Role Does Cell Division Play in a Sexual Life Cycle? Page: 223 Bloom’s Category: 1. Remembering

26. During prophase I of meiosis, a unique event called ______results in the formation of recombinant chromosomes. Answer: crossing over Textbook Reference: 11.5 What Happens during Meiosis? Page: 226 Bloom’s Category: 1. Remembering

27. A cell with three homologous sets of chromosomes is called a(n) ______cell. Answer: triploid Textbook Reference: 11.5 What Happens during Meiosis? Page: 226 Bloom’s Category: 1. Remembering

28. Occasionally, a homologous chromosome pair fails to separate during anaphase I of meiosis. One of the resulting cells lacks a copy of this chromosome, whereas the other contains both members of the homologous pair. These cells are called ______cells. Answer: aneuploid Textbook Reference: 11.5 What Happens during Meiosis? Page: 228 Bloom’s Category: 1. Remembering

29. Nondisjunction causes the production of ______cells. Answer: aneuploid Textbook Reference: 11.5 What Happens during Meiosis? Page: 228 Bloom’s Category: 2. Understanding

30. Down syndrome can be caused by an extra chromosome ______. Answer: 21 Textbook Reference: 11.5 What Happens during Meiosis? Page: 228–229 Bloom’s Category: 1. Remembering

31. During a process known as ______, a piece of one chromosome breaks off and becomes joined to a different chromosome. Answer: translocation Textbook Reference: 11.5 What Happens during Meiosis? Page: 229 Bloom’s Category: 1. Remembering

32. A mutated form of normal cell proteins that stimulate cancer cells to divide frequently is known as a(n) ______. Answer: oncogene Textbook Reference: 11.7 How Does Unregulated Cell Division Lead to Cancer? Page: 231 Bloom’s Category: 1. Remembering

Diagram

1. Refer to the diagram below of a phase of mitosis. Which cell structure is indicated by the two leaders? a. Chromosome b. Centromere c. Chromatid d. Kinetochore microtubule e. Centrioles Answer: d Textbook Reference: 11.3 What Happens during Mitosis? Page: 218 Bloom’s Category: 4. Analyzing

STUDY GUIDE QUESTIONS (By Nancy Guild)

Knowledge and Synthesis

1. Which of the following statements about mitosis is true? a. Cytokinesis follows mitosis. b. DNA replication is completed prior to the beginning of this phase. c. The chromosome number of the resulting cells is the same as that of the parent cell. d. The daughter cells are genetically identical to the parental cell. e. All of the above Answer: e Feedback: Mitosis occurs after DNA replication and results in cells with the same number of genetically identical chromosomes as the parent cell. Cytokinesis follows mitosis. Textbook Reference: 11.3 What Happens during Mitosis? Page: 217

2. Which of the following statements about meiosis is true? a. The chromosome number in the resulting cells is halved. b. DNA replication occurs before meiosis I and meiosis II. c. The homologs do not pair during prophase I. d. The daughter cells are genetically identical to the parental cell. e. The chromosome number of the resulting cells is the same as that of the parent cell. Answer: a Feedback: Meiosis occurs after one round of DNA replication. Homologous chromosomes pair during prophase I of meiosis, and after meiosis II the resulting cells have half the number of chromosomes as the parent cell. Those chromosomes are not genetically identical to the parental cells. Textbook Reference: 11.5 What Happens during Meiosis? Page: 227

3. Which of the following statements about kinetochores on mitotic chromosomes is true? a. They are located at the centromere of each chromosome. b. They are the sites where microtubules attach to separate the chromosomes. c. They are organized so that there is one per sister chromatid. d. Kinetochore microtubules from opposite poles attach to each sister chromatid. e. All of the above Answer: e Feedback: Kinetochores, one per sister chromatid, are assembled at the centromere of each chromosome and are the sites in which microtubules from opposite poles attach to segregate the chromosomes. Textbook Reference: 11.3 What Happens during Mitosis? Page: 217–219

4. Which of the following statements about the mitotic spindle is true? a. It is composed of polar and kinetochore microtubules, both of which attach to chromosomes. b. It is composed of actin and myosin microfilaments. c. It is composed of kinetochores at the metaphase plate. d. It is composed of microtubules, which help separate the chromosomes to opposite poles of the cell. e. It originates only at the centrioles in the centrosomes. Answer: d Feedback: The mitotic spindle is composed of microtubules, not actin and myosin filaments. The spindle originates from the centrosome, which may or may not have centrioles, and only the kinetochore microtubules attach to the chromosomes. Textbook Reference: 11.3 What Happens during Mitosis? Page: 216–217

5. Imagine that there is a mutation in the Cdk gene such that its gene product is nonfunctional. What kind of effect would this mutation have on a mature red blood cell? a. The cyclin that bound to this Cdk would not be phosphorylated. b. There would be no effect, because mature red blood cells do not enter the cell cycle. c. The cell would be unable to replicate its DNA. d. The cell would not be able to enter G1. e. The cell would be unable to reproduce itself. Answer: b Feedback: Many cells, such as red blood cells, muscle cells, and nerve cells, lose their ability to divide as they mature. Textbook Reference: 11.2 How Is Eukaryotic Cell Division Controlled? Page: 214–215

6. Imagine that there is a mutation in the Cdk gene such that its gene product is nonfunctional. What kind of effect would this mutation have on a mammalian white blood cell? a. The cell would be unable to replicate its DNA. b. The cell would be unable to enter mitosis. c. The cell would be unable to reproduce itself. d. The cell would not be able to phosphorylate its associated cyclin. e. All of the above Answer: e Feedback: Cyclin-Cdk’s affect the transition into DNA replication into mitosis and are required for cell division. Functional Cdk is required to phosphorylate its associated cyclin. Textbook Reference: 11.2 How Is Eukaryotic Cell Division Controlled? Page: 214–215

7. Which of the following statements about DNA replication and cytokinesis in Escherichia coli is true? a. DNA replication occurs in the nucleus. b. Cytokinesis is facilitated by microfilaments of actin and myosin. c. DNA replication occurs during the S phase of the cell cycle. d. Cell reproduction is initiated by reproductive signals, which result in DNA replication, DNA segregation, and cytokinesis. e. The E. coli chromosome is linear. Answer: d Feedback: Escherichia coli is a prokaryote. It lacks a nucleus and does not undergo the cell cycle seen in eukaryotes. It has a circular chromosome, and does not synthesize actin or myosin proteins. Cytokinesis in E. coli is a result of a reproductive signal that causes the DNA to be replicated and segregated and finally causes the cell to divide. Textbook Reference: 11.1 How Do Prokaryotic and Eukaryotic Cells Divide? Page: 210–211

8. Which of the following statements about chromatids is true? a. They are replicated chromosomes still joined together at the centromere. b. They are identical in mitotic chromosomes. c. They undergo recombination in mitosis. d They are identical in meiotic chromosomes. e. Both a and b Answer: e Feedback: Chromatids are highly condensed, newly replicated chromosomes, which will be segregated to the daughter cells. After DNA replication, chromatids are still attached to each other at the centromere. Meiotic sister chromatids are different from each other due to recombination (crossing over) in prophase of meiosis I. Mitotic sister chromatids are identical. Textbook Reference: 11.3 What Happens during Mitosis? Page: 215–216

9. Histones are positively charged because a. the majority of the ions in the nucleus of the cell are negatively charged. b. histones interact with acidic residues of proteins found in the nucleus. c. the basic side chains of histone proteins interact with the negatively charged DNA. d. histones have a majority of acidic residues in their protein sequence. e. the pH of the nucleus needs to be increased. Answer: c Feedback: The positive charges on histone proteins are due to the large number of basic amino acid residues found in these proteins. These positive charges interact with the negatively charged phosphate sugar backbone of DNA during assembly of the DNA on the nucleosome. Textbook Reference: 11.3 What Happens during Mitosis? Page: 216–217

10. Chromosome movement during anaphase is the result of a. the hydrolysis of ATP by dynein. b. molecular motors at the kinetochores that move the chromosomes toward the poles. c. molecular motors at the centrosome that pull the microtubules toward the poles. d. shortening of the microtubules at the centrosome that pull the chromosomes toward the poles. e. a, b, and d Answer: e Feedback: Chromosomes are attached to the microtubules at their kinetochores. There are dynein molecular motors at the kinetochores (but not the centrosome) which hydrolyze ATP and help move the chromosomes to opposite poles. Chromosomes are also pulled toward the poles by the shortening of the kinetochore microtubules. Textbook Reference: 11.3 What Happens during Mitosis? Page: 219

11. Programmed cell death (apoptosis) a. occurs in cells that have been deprived of essential nutrients. b. occurs only in cells that have damaged DNA. c. is a natural process during development. d. is signaled by the initiation of mitosis. e. is well controlled in cancer cells. Answer: c Feedback: Programmed cell death occurs during the development of many organisms (for instance, tadpoles lose their tails to become adult frogs). One of the stimuli for programmed cell death is DNA damage, but it is not the only cause of death. Necrosis (cell death that is not programmed) occurs when cells have been deprived of essential nutrients. The initiation of mitosis is part of the cell cycle, in which cells reproduce, and is not a step in programmed cell death. Apoptosis is not well controlled in cancer cells. Textbook Reference: 11.6 In a Living Organism, How Do Cells Die? Page: 229–230

12. If the ori site on the E. coli chromosome is deleted, a. nothing will happen. b. replication will start but not be able to continue. c. replication will not start. d. replication will initiate at another ori site on the chromosome. e. the chromosome will be replicated but the cell will not be able to divide. Answer: c Feedback: Without the origin of replication (there is only one in E. coli), there would be no site for the replication proteins to bind to initiate DNA replication, so DNA synthesis would not start. Textbook Reference: 11.1 How Do Prokaryotic and Eukaryotic Cells Divide? Page: 211

13. Chiasmata a. are sites where nonsister chromatids can exchange genetic material during meiosis. b. are sites where sister chromatids can exchange genetic material during meiosis. c. increase genetic variation among the products of meiosis. d. increase genetic variation among the products of mitosis. e. Both a and c Answer: e Feedback: Chiasmata are sites where nonsister chromatids can exchange genetic material during meiosis, which increases genetic variation in the gametes (the products of meiosis). Textbook Reference: 11.5 What Happens during Meiosis? Page: 226

14. The difference between asexual and sexual reproduction is that a. asexual reproduction occurs only in bacteria, whereas sexual reproduction occurs in plants and animals. b. asexual reproduction results from meiosis, whereas sexual reproduction results from mitosis. c. asexual reproduction results in an organism that is identical to the parent, whereas sexual reproduction results in an organism that is not identical to either parent. d. asexual reproduction results from the fusion of two gametes, whereas sexual reproduction produces clones of the parent organism. e. asexual reproduction occurs only in haplontic organisms, whereas sexual reproduction occurs only in diplontic organisms. Answer: c Feedback: Asexual reproduction, which results from mitosis, produces cells that are identical to the parent and can occur in plants. Sexual reproduction can occur in haplontic organisms (such as fungi) and results in an organism that is not genetically identical to either parent. Textbook Reference: 11.4 What Role Does Cell Division Play in a Sexual Life Cycle? Page: 221–222

15. A chromatid is a. a chromosome before it has undergone DNA replication. b. one of the pairs of homologous chromosomes. c. a homologous chromosome. d. a newly replicated bacterial chromosome. e. one-half of a newly replicated eukaryotic chromosome. Answer: e Feedback: A chromatid is one-half of a newly replicated eukaryotic chromosome, and is connected to the other (sister) chromatid at the centromere. Textbook Reference: 11.3 What Happens during Mitosis? Page: 215–216

Application

1. How is cell division different in prokaryotic cells and eukaryotic cells? Answer: In most prokaryotic cells there is only one circular chromosome. As the cell enlarges to prepare for division, the newly replicated daughter chromosomes are separated at opposite sides of the cell. During fission, the cell membrane pinches in, and cell wall components are synthesized between the daughter cells. In eukaryotic cells, there are more chromosomes, and they are linear. The cell undergoes a sequential set of steps called the cell cycle, in which the chromosomes are replicated and then separated to opposite poles of the cell. Microtubules are used to segregate the chromosomes equally into the daughter cells, and actin filaments and myosin cause the cell membrane to form a contractile ring and separate to form two daughter cells. Textbook Reference: 11.1 How Do Prokaryotic and Eukaryotic Cells Divide? Page: 210–211

2. By using a chemical that inhibits cytokinesis, you have created peaches that are tetraploid. How many sets of chromosomes do these peaches have? (What is the ploidy of these chromosomes?) Will these peaches produce gametes that are fertile? What if the peaches were triploid? Answer: Peaches that are tetraploid have four sets of chromosomes. Because there are an even number of chromosomes (4n), each replicated homologous chromosome will be able to find a replicated homolog to pair with at meiosis and will produce fertile gametes. These gametes will be diploid. Triploid cells will not be fertile because one of the three homologs will not find its pair during prophase of meiosis I, and the single homologs will be segregated randomly into the daughter cells. Textbook Reference: 11.5 What Happens during Meiosis? Page: 229

3. How does cytokinesis differ in animal and plant cells? Answer: In animal cells, cytokinesis results from the interaction of actin filaments and myosin, which causes the cell membrane to pinch in and divide the cytoplasm into two cells. In plant cells, a cell plate forms between the newly segregated chromosomes, and Golgi vesicles fuse at that site to form the new cell membranes. Cell wall components are then secreted between the plasma membranes to complete cytokinesis. Textbook Reference: 11.3 What Happens during Mitosis? Page: 220

4. Describe how two meters of DNA in a typical human cell can fit into the nucleus, which is 5 µm in diameter. Answer: See Figures 11.8 and 11.9. Textbook Reference: 11.3 What Happens during Mitosis? Page: 217, Figure 11.9

5. Describe two ways that the genetic diversity of organisms is increased during meiosis. Answer: Genetic diversity is increased during crossing over of prophase I of meiosis so that each gamete has chromosomes with different combinations of alleles. During meiosis, each homologous chromosome is randomly segregated to one of the two poles, resulting 223 different possible combinations of homologous chromosomes per gamete. Textbook Reference: 11.5 What Happens during Meiosis? Page: 226–227

TEXTBOOK SELF-QUIZ

1. Which statement about eukaryotic chromosomes is not true? a. They sometimes consist of two chromatids. b. They sometimes consist only of a single chromatid. c. They normally possess a single centromere. d. They consist only of proteins. e. During metaphase they are visible under the light microscope. Answer: d

2. Nucleosomes a. are made of chromosomes. b. consist entirely of DNA. c. consist of DNA wound around a histone core. d. are present only during mitosis. e. are present only during prophase. Answer: c

3. Which statement about the cell cycle is not true? a. It consists of interphase, mitosis, and cytokinesis. b. The cell’s DNA replicates during G1. c. A cell can remain in G1 for weeks or much longer. d. DNA is not replicated during G2. e. Cells enter the cell cycle as a result of internal or external signals. Answer: b

4. Which statement about mitosis is not true? a. A single nucleus gives rise to two identical daughter nuclei. b. The daughter nuclei are genetically identical to the parent nucleus. c. The centromeres separate at the onset of anaphase. d. Homologous chromosomes synapse in prophase. e. The centrosomes organize the microtubules of the spindle fibers. Answer: d

5. Which statement about cytokinesis is true? a. In animals, a cell plate forms. b. In plants, it is initiated by furrowing of the membrane. c. It follows mitosis. d. In plant cells, actin and myosin play an important part. e. It is the division of the nucleus. Answer: c

6. Apoptosis a. occurs in all cells. b. involves the formation of the plasma membrane. c. does not occur in an embryo. d. is a series of programmed events resulting in cell death. e. is the same as necrosis. Answer: d

7. In meiosis, a. meiosis II reduces the chromosome number from diploid to haploid. b. DNA replicates between meiosis I and meiosis II. c. the chromatids that make up a chromosome in meiosis II are identical. d. each chromosome in prophase I consists of four chromatids. e. homologous chromosomes separate from one another in anaphase I. Answer: e

8. In meiosis, a. a single nucleus gives rise to two daughter nuclei. b. the daughter nuclei are genetically identical to the parent nucleus. c. the centromeres separate at the onset of anaphase I. d. homologous chromosomes synapse in prophase I. e. no spindle forms. Answer: d

9. An animal has a diploid chromosome number of 12. An egg cell of that animal has 5 chromosomes. The most probable explanation is a. normal mitosis. b. normal meiosis. c. nondisjunction in meiosis I. d. nondisjunction in meiosis I or II. e. nondisjunction in mitosis. Answer: d

10. The number of daughter chromosomes in a human cell (diploid number 46) in anaphase II of meiosis is a. 2. b. 23. c. 46. d. 69. e. 92. Answer: c

BIOPORTAL DIAGNOSTIC QUIZ (Personalized Study Plan Quiz) (By Richard McCarty)

1. Chloroplasts contain DNA and reproduce by fission, much like bacteria. DNA replication is not synchronized with chloroplast division. Yet, after division, both daughter chloroplasts contain DNA. How? a. There are a large number of DNA molecules per chloroplast. b. The DNA is organized into nucleosomes. c. There is a mitotic spindle in dividing chloroplasts. d. Chloroplast DNA is circular. e. None of the above Answer: a Textbook Reference: 11.1 How Do Prokaryotic and Eukaryotic Cells Divide? Page: 210–211 Bloom’s Category: 2. Understanding

2. DNA replication occurs a. before both mitosis and meiosis. b. only before mitosis. c. only before meiosis. d. during chromosome condensation. e. during G2. Answer: a Textbook Reference: 11.2 How Is Eukaryotic Cell Division Controlled? Page: 212–213 Bloom’s Category: 1. Remembering

3. Interphase involves all of the following steps except a. DNA replication. b. the synthesis of cellular components necessary for mitosis. c. the conservation of energy for later stages of mitosis. d. the condensation of chromatin. e. All of the above Answer: d Textbook Reference: 11.2 How Is Eukaryotic Cell Division Controlled? Page: 212–213 Bloom’s Category: 2. Understanding

4. Which of the following statements about cyclin-dependent kinases (Cdk’s) or cyclin is false? a. Different Cdk’s act at different points in the cell cycle. b. A Cdk can catalyze the phosphorylation of retinoblastoma protein. c. Phosphorylated retinoblastoma protein is inactive. d. Cdk’s use ATP as a substrate. e. Cyclin is made continuously during the cell cycle. Answer: e Textbook Reference: 11.2 How Is Eukaryotic Cell Division Controlled? Page: 214–215 Bloom’s Category: 1. Remembering

5. Which stage of mitosis includes the formation of kinetochores? a. Metaphase b. Anaphase c. Telophase d. Prophase e. Interphase Answer: d Textbook Reference: 11.3 What Happens during Mitosis? Page: 216–217 Bloom’s Category: 1. Remembering

6. In a metaphase chromosome, DNA is combined with ______, called ______, to form structures known as ______. a. proteins; nucleoproteins; centrosomes b. nucleic acids; nucleosomes; histones c. proteins; histones; nucleosomes d. small molecules; histones; nucleosomes e. proteins; nucleosomes; histones Answer: c Textbook Reference: 11.3 What Happens during Mitosis? Page: 216–217 Bloom’s Category: 2. Understanding

7. The mitotic spindle a. is composed of intermediate filaments. b. begins to form during metaphase. c. is composed of two different types of microtubules. d. provides the force needed for chromosome movement. e. plays a role in cytokinesis. Answer: c Textbook Reference: 11.3 What Happens during Mitosis? Page: 216–217 Bloom’s Category: 1. Remembering

8. In human cells, chromosomes are a. always condensed during the entire cell cycle. b. different in different tissues. c. connected by centromeres, except for the X and Y. d. the same size and length. e. visible only during mitosis and meiosis. Answer: e Textbook Reference: 11.3 What Happens during Mitosis? Page: 216–218 Bloom’s Category: 2. Understanding

9. Anaphase a. is the phase when sister chromatids separate and move to opposite poles. b. involves chromosomes lining up at the equatorial plate. c. occurs before the nuclear envelope breaks down. d. takes place just before cytokinesis. e. Both a and c Answer: a Textbook Reference: 11.3 What Happens during Mitosis? Page: 218–219 Bloom’s Category: 2. Understanding

10. Which of the following statements about asexual reproduction is true? a. In asexual reproduction, progeny are haploid. b. It requires meiosis. c. In asexual reproduction, there is genetic variation among the offspring. d. In asexual reproduction, two gametes fuse to produce a zygote. e. It produces offspring that are genetically identical to the parent. Answer: e Textbook Reference: 11.4 What Role Does Cell Division Play in a Sexual Life Cycle? Page: 221 Bloom’s Category: 1. Remembering

11. In sexually reproducing organisms, the diploid phase of the life cycle begins at a. spore formation. b. gamete formation. c. meiosis. d. mitosis. e. fertilization. Answer: e Textbook Reference: 11.4 What Role Does Cell Division Play in a Sexual Life Cycle? Page: 222 Bloom’s Category: 1. Remembering

12. Human chromosomes a. are all of similar size. b. may be visualized during prophase. c. may be visualized during metaphase. d. are all of similar shape. e. all have centromeres in the same position. Answer: d Textbook Reference: 11.4 What Role Does Cell Division Play in a Sexual Life Cycle? Page: 223 Bloom’s Category: 4. Analyzing

13. In meiosis II, a. four genetically identical cells are generated. b. sister chromatids are separated. c. DNA replication occurs. d. crossing over occurs. e. Both a and b Answer: b Textbook Reference: 11.5 What Happens during Meiosis? Page: 225 Bloom’s Category: 2. Understanding

14. Homologous chromosomes undergo crossing over during a. prophase I of mitosis. b. prophase II of meiosis. c. prophase I and II of meiosis. d. prophase I of meiosis. e. anaphase II of meiosis. Answer: d Textbook Reference: 11.5 What Happens during Meiosis? Page: 226 Bloom’s Category: 2. Understanding

15. In contrast to mitosis, in meiosis a. genetically identical daughter cells are produced. b. pairing of homologous chromosomes occurs. c. crossing over can take place. d. there is no cytokinesis. e. Both b and c Answer: e Textbook Reference: 11.5 What Happens during Meiosis? Page: 227 Bloom’s Category: 1. Remembering

16. A human cell in G1 of the cell cycle has 46 (23 pairs) of chromosomes. The number of daughter chromosomes in telophase II of meiosis is a. 23. b. 46. c. 92. d. 34.5. e. 69. Answer: c Textbook Reference: 11.5 What Happens during Meiosis? Page: 227–228 Bloom’s Category: 2. Understanding

17. Which of the following statements about aneuploidy is false? a. It results from chromosomal nondisjunction. b. It does not occur in humans. c. An individual with an extra chromosome is trisomic. d. Trisomies are common in human zygotes. e. A piece of one chromosome may translocate to another chromosome. Answer: b Textbook Reference: 11.6 In a Living Organism, How Do Cells Die? Page: 228–229 Bloom’s Category: 1. Remembering

18. Polyploidy a. is common in fungi. b. is common in higher plants. c. can result in crop plants that have larger fruit than diploid plants. d. can result in sterility. e. All of the above Answer: e Textbook Reference: 11.6 In a Living Organism, How Do Cells Die? Page: 229 Bloom’s Category: 2. Understanding

19. Apoptosis a. occurs only in animals. b. is triggered solely by signals external to the cell. c. occurs only during development. d. is similar to necrosis. e. is controlled by signal transduction pathways. Answer: e Textbook Reference: 11.6 In a Living Organism, How Do Cells Die? Page: 229–230 Bloom’s Category: 2. Understanding

20. 5-Florouracil and taxol both block ______, the former by ______and the latter by blocking ______. a. apoptosis; damaging DNA; cytokinesis b. the cell cycle; blocking DNA replication; spindle formation c. apoptosis; blocking DNA replication; spindle formation d. the cell cycle; damaging DNA; cytokinesis. e. the cell cycle; blocking DNA replication; cytokinesis Answer b Textbook Reference: 11.7 How Does Unregulated Cell Division Lead to Cancer? Page: 232 Bloom’s Category 2: Understanding