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1. HeLa cells, which have been used for more than fifty years in biomedical research,
b. can live and multiply outside the body.
2. A bacterial cell gives rise to two genetically identical daughter cells by a process known as
3. In order for a prokaryote cell to divide, which of the following must occur?
a. A reproductive signal, replication, segregation of DNA, and cytokinesis
4. During bacterial cell division, the two DNA molecules are separated by
d. pinching of the plasma membrane.
5. During prokaryotic cell division, two chromosomes separate from each other and distribute into the daughter cells by
d. attachment to separating membrane regions.
6. Bacteria typically have _______, whereas eukaryotes have _______.
a. one chromosome that is circular; many chromosomes that are linear
7. Which of the following statements about mitosis is true?
d. Two genetically identical daughter cells are formed.
8. DNA replication occurs
d. during the S phase.
9. Mature nerve cells, which are incapable of cell division, are most likely in
10. The cells of the intestinal epithelium are continually dividing, replacing dead cells lost from the surface of the intestinal lining. If you examined a population of intestinal epithelial cells under the microscope, most of the cells would
c. be in interphase.
11. Cells that do not divide are usually arrested in
12. Which of the following phases of the cell cycle is not part of interphase?
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.
14. A cell cycle consists of
d. interphase and mitosis.
15. Evidence from yeast suggests that the maturation-promoting factor of sea urchins is
d. a Cdk.
16. The initiation of the S phase and the M phase of the cell cycle depends on a pair of biochemicals called _______ and _______.
b. Cdk’s; cyclin
17. When cyclin binds Cdk,
b. kinase activation occurs.
18. Cyclin-dependent kinases (Cdk’s) catalyze the phosphorylation of targeted proteins, a process that
c. changes the shape and function of the targeted proteins.
19. Regulation of the cell cycle is dependent upon cyclins and cyclin-dependent kinases. The key(s) that allows a cell to progress beyond the restriction point is (are)
d. phosphorylation of RB by Cdk4 and Cdk2.
20. DNA damage by UV radiation causes the synthesis of
21. Half of all human cancers have defective _______ associated with their cells.
22. The uncondensed length of human DNA found in chromosomes is _______, whereas a typical cell is 10 µm in length.
c. 2 meters
23. Chromosomes contain large amounts of interacting proteins known as
24. The molecules that make up a chromosome are _______ and _______.
b. DNA; proteins
25. The basic structure of chromatin has sometimes been referred to as beads on a string of DNA. These beads are called
26. Chromatin consists of
b. DNA, histones, and many other nonhistone proteins.
27. Nucleosomes are composed of _______ and _______.
d. histones; DNA
28. The DNA of a eukaryotic cell is
29. Around _______ base pairs wrap around each core particle in a _______.
c. 146; nucleosome
30. Interleukins and erythropoietin are
a. growth factors.
31. 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
32. The products of mitosis are
e. two genetically identical nuclei.
33. The mitotic spindle is composed of
34. Which of the following does not occur during mitotic prometaphase?
d. Synapsis of homologous chromosomes
b. determine the plane of cell division.
36. When dividing cells are examined under a light microscope, chromosomes first become visible during
37. The structures that line up the chromatids on the equatorial plate during metaphase are called
b. polar and kinetochore microtubules.
38. The microtubules of the mitotic spindle attach to a specialized structure in the centromere region of each chromosome called the
39. Chromatin condenses to form discrete, visible chromosomes
d. during prophase.
40. Microtubules that form the mitotic spindle tend to originate from or terminate in
e. centrioles and kinetochores.
41. After the centromeres separate during mitosis, the chromatids, now called _______, move toward opposite poles of the spindle.
e. daughter chromosomes
42. During mitotic anaphase, chromatids migrate
b. from the metaphase plate toward the poles.
43. At the milestone that defines metaphase, the chromosomes
d. line up at the equatorial plate.
44. At the milestone that defines anaphase, the chromosomes
45. The energy to move chromosomes during mitosis is provided by
46. The sizes and shapes of chromosomes can be observed most easily in a cell that is in
47. The spindle checkpoint is a process
c. that determines whether all kinetochores are attached to the spindle.
48. Paired chromatids separate and move to opposite poles because
a. sister chromatids attach to microtubules in opposite halves of the spindle.
49. At the milestone that defines telophase, the chromosomes
c. are at opposite poles.
50. Chromosomes “decondense” into diffuse chromatin
a. at the end of telophase.
51. In plant cells, cytokinesis is accomplished by the formation of a(n)
d. cell plate.
52. The event in the cell division process that clearly involves microfilaments is
e. cytokinesis in animal cells.
53. Which of the following statements about plant cytokinesis is true?
d. Vesicles fuse to form a cell plate.
54. The distribution of mitochondria between the daughter cells during cytokinesis
a. is random.
55. Genetically diverse offspring result from
c. sexual reproduction.
56. The major drawback of asexual reproduction is that it
e. produces a lack of variation among the progeny.
57. A haploid cell is a cell
b. containing only one copy of each chromosome.
58. Sexual reproduction increases genetic variability through
d. crossing over, independent assortment, and random fertilization.
59. The second meiotic division of meiosis is important because
d. without this division, chromosome copies would double at each fertilization.
60. During asexual reproduction, the genetic material of the parent is passed on to the offspring by
c. mitosis and cytokinesis.
61. All zygotes are
62. In all sexually reproducing organisms, the diploid phase of the life cycle begins at
63. Diploid cells of the fruit fly Drosophila have ten chromosomes. How many chromosomes does a Drosophila gamete have?
64. The members of a homologous pair of chromosomes
a. are identical in size and appearance.
65. Asexual reproduction produces genetically identical individuals because
c. no meiosis or fertilization take place.
66. Which of the following is not part of sexual reproduction?
b. The fusion of sister chromatids during fertilization
67. Each diploid cell of a human female contains _______ of each type of chromosome.
68. Which of the following statements about homologous chromosome pairs is false?
a. They come from only one of the individual’s parents.
69. In a haploid organism, most mitosis occurs
b. after meiosis and before fertilization.
70. The diagnosis of Down syndrome is made by examining the individual’s
71. Human males have ____ sex chromosomes.
72. Meiosis can occur
b. only when an organism is diploid.
73. During meiosis, the sister chromatids separate during
a. anaphase II.
74. At the end of the first meiotic division, each chromosome consists of
d. two chromatids.
75. Which of the following statements about sister chromatids is false?
d. They separate from each other during meiosis I.
76. 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.
77. The exchange of genetic material between chromatids on homologous chromosomes occurs during
c. prophase I.
78. Genetic recombination occurs during
a. prophase of meiosis I.
79. The number of chromosomes is reduced to half during
c. meiosis I.
80. The total DNA content of each daughter cell is reduced during meiosis because
b. chromosomes do not replicate between meiosis I and II.
81. Accidents during meiosis that can result in trisomies and monosomies are called
82. Chromosome number is reduced during meiosis because the process consists of
d. two cell divisions and only a single round of chromosome replication.
83. A potato has a diploid number of 48. If an egg of this plant has 23 chromosomes, the most likely explanation is that
b. nondisjunction occurred during meiosis I.
84. 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
e. crossing over during prophase I.
85. During meiosis I in humans, one of the daughter cells receives
b. a mixture of maternal and paternal chromosomes.
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.
87. A person with Klinefelter syndrome has 44 chromosomes and three sex chromosomes (XXY). The resulting aneuploidy is caused by
88. One difference between mitosis and meiosis I is that
c. homologous chromosome pairs synapse during meiosis but not during mitosis.
89. 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.
90. How does mitotic prophase differ from prophase I of meiosis?
e. Crossing over is characteristic of prophase I of meiosis but not of mitotic prophase.
91. A triploid nucleus cannot undergo meiosis because
b. not all of the chromosomes can form homologous pairs.
92. A triploid plant has
b. one extra set of chromosomes.
93. The process of programmed cell death is called
94. An indicator of programmed cell death is
a. fragmented chromatin.
95. Which of the following statements about necrosis is true?
c. It may occur when cells are damaged by toxins.
1. The orderly distribution of genetic information occurs in prokaryotic cells by a process known as _______.
2. The heritable information of the cell is _______.
3. Prokaryotic DNA molecules are packaged by _______ proteins, which associate with DNA.
4. Bacteria have a short sequence called _______ where DNA synthesis begins.
5. Bacteria have a short sequence called _______ where DNA synthesis ends.
6. When a DNA molecule doubles, a chromosome is then made up of two joined _______.
7. The process that ensures that only one of each pair of chromosomes is included in a gamete is _______.
8. The stage of the cell cycle during which DNA replicates is called the _______.
9. The G2 phase always follows _______ phase.
10. The G in G1 and G2 is short for “_______.”
11. In order to divide, cells must be stimulated by external chemical signals called ______.
12. The structure present during mitosis that is composed of two identical DNA molecules complexed with proteins and joined at the centromere is called a _______.
13. The process that ensures that genetic information is passed on to a cell’s daughter cells is _______.
14. The main role of nucleosomes in eukaryotic cells is to _______ the DNA.
15. The milestone event that defines entry into prometaphase is loss of the _______.
16. During prometaphase, the chromatids are held together by _______.
17. The chromatin _______ during prophase.
18. In general, the division of the cell, called _______, follows immediately upon mitosis.
19. In plants, a _______ forms at the equatorial region of the cell.
20. The cell plate is derived from the _______ of the cell.
21. The “invisible thread” that pinches cells apart during cell division is made of _______ and _______.
22. A zygote usually has _______ copies of each chromosome.
23. A _______ is one of a pair of chromosomes having the same overall genetic composition and sequence.
24. _______ is the fusion of two gametes.
25. The _______ is the number, form, and type of chromosomes found in a cell.
26. During prophase I of meiosis, a unique event called _______ results in the formation of recombinant chromosomes.
27. 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.
28. Nondisjunction causes the production of _______ cells.
29. Down syndrome can be caused by an extra chromosome _______.
30. During a process known as _______, a piece of one chromosome breaks off and becomes joined to a different chromosome.
31. A cell with three homologous sets of chromosomes is called a _______ cell.
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