7e Biology, (Campbell)
Chapter 12: The Cell Cycle
Chapter Questions
1) The centromere is a region in which A) chromatids are attached to one another. B) metaphase chromosomes become aligned. C) chromosomes are grouped during telophase. D) the nucleus is located prior to mitosis. E) new spindle microtubules form. 2) What is a chromatid? A) a chromosome in G1 of the cell cycle B) a replicated chromosome C) a chromosome found outside the nucleus D) a special region that holds two centromeres together E) another name for the chromosomes found in genetics 3) What is the name for the special region on a duplicated chromosome that holds the sister chromatids together? A) centrosome B) centromere C) kinetochore D) desmosome E) microtubule organizer region 4) Starting with a fertilized egg (zygote), a series of five cell divisions would produce an early embryo with how many cells? A) 4 B) 8 C) 16 D) 32 E) 64
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5) If there are 20 chromatids in a cell, how many centromeres are there? A) 10 B) 20 C) 30 D) 40 E) 80 6) Which of the following statements is not true? A) Mitosis produces new nuclei with exactly the same chromosomal endowment as the parent nucleus. B) Mitosis may occur without cytokinesis. C) Mitosis and cytokinesis are required for asexual reproduction. D) All cells come from a preexisting cell. E) The mitotic spindles in prokaryotic cells are composed of microtubules.
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Use the following information to answer the questions below. The lettered circle in Figure 12.1 shows a diploid nucleus with four chromosomes. There are two pairs of homologous chromosomes, one long and the other short. One haploid set is symbolized as black and the other haploid set is gray. The chromosomes in the unlettered circle have not yet replicated. Choose the correct chromosomal conditions for the following stages.
Figure 12.1 7) at prometaphase of mitosis 8) one daughter nucleus at telophase of mitosis The questions below refer to the following terms. Each term may be used once, more than once, or not at all. A. B. C. D. E. telophase anaphase prometaphase metaphase prophase
9) Two centrosomes are arranged at opposite poles of the cell.
10) Centrioles begin to move apart in animal cells. 11) This is the longest of the mitotic stages. 12) Centromeres uncouple, sister chromatids are separated, and the two new chromosomes move to opposite poles of the cell. 13) If cells in the process of dividing are subjected to colchicine, a drug that interferes with the functioning of the spindle apparatus, at which stage will mitosis be arrested? A) anaphase B) prophase C) telophase
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D) metaphase E) interphase 14) A cell containing 92 chromatids at metaphase of mitosis would, at its completion, produce two nuclei containing how many chromosomes? A) 12 B) 16 C) 23 D) 46 E) 92
Figure 12.2 15) If the cell whose nuclear material is shown in Figure 12.2 continues toward completion of mitosis, which of the following events would occur next? A) cell membrane synthesis B) spindle fiber formation C) nuclear envelope breakdown D) formation of telophase nuclei E) synthesis of chromatids 16) All of the following occur during prophase of mitosis in animal cells except A) the centrioles move toward opposite poles. B) the nucleolus can no longer be seen. C) the nuclear envelope disappears. D) chromosomes are duplicated. E) the spindle is organized. 17) If there are 20 centromeres in a cell at anaphase, how many chromosomes are there in each daughter cell following cytokinesis? A) 10 B) 20 C) 30 D) 40 E) 80
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18) If there are 20 chromatids in a cell at metaphase, how many chromosomes are there in each daughter cell following cytokinesis? A) 10 B) 20 C) 30 D) 40 E) 80 Use the data in Table 12.1 to answer the following questions. The data were obtained from a study of the length of time spent in each phase of the cell cycle by cells of three eukaryotic organisms designated beta, delta, and gamma. Table 12.1: Minutes Spent in Cell Cycle Phases
(( ( ( ( ( X ( ( (( ( ( ( (
( X
19) Of the following, the best conclusion concerning the difference between the S phases for beta and gamma is that A) gamma contains more DNA than beta. B) beta and gamma contain the same amount of DNA. C) beta contains more RNA than gamma. D) gamma contains 48 times more DNA and RNA than beta. E) beta is a plant cell and gamma is an animal cell. 20) The best conclusion concerning delta is that the cells A) contain no DNA. B) contain no RNA. C) contain only one chromosome that is very short. D) are actually in the G0 phase. E) divide in the G1 phase. 21) How is the S phase of the cell cycle measured? A) counting the number of cells produced per hour B) determining the length of time during which DNA synthesis occurred in the cells C) comparing the synthesis versus the breakdown of S protein D) determining when the S chromosome is synthesized E) stopping G1 and measuring the number of picograms of DNA per cell
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22) Where do the microtubules of the spindle originate during mitosis in both plant and animal cells? A) centromere B) centrosome C) centriole D) chromatid E) kinetochore
23) All of the following occur during mitosis except the A) condensing of chromosomes. B) uncoupling of chromatids at the centromere. C) formation of a spindle. D) synthesis of DNA. E) disappearance of the nucleolus. 24) If a cell has 8 chromosomes at metaphase of mitosis, how many chromosomes will it have during anaphase? A) 1 B) 2 C) 4 D) 8 E) 16 25) Cytokinesis usually, but not always, follows mitosis. If a cell completed mitosis but not cytokinesis, the result would be a cell with A) a single large nucleus. B) high concentrations of actin and myosin. C) two abnormally small nuclei. D) two nuclei. E) two nuclei but with half the amount of DNA. 26) Regarding mitosis and cytokinesis, one difference between higher plants and animals is that in plants A) the spindles contain microfibrils in addition to microtubules, whereas animal spindles do not contain microfibrils. B) sister chromatids are identical, but they differ from one another in animals. C) a cell plate begins to form at telophase, whereas animals a cleavage furrow is initiated at that stage. D) chromosomes become attached to the spindle at prophase, whereas in animals chromosomes do not become attached until anaphase. E) spindle poles contain centrioles, whereas spindle poles in animals do not.
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27) How do the daughter cells at the end of mitosis and cytokinesis compare with their parent cell when it was in G1 of the cell cycle? A) The daughter cells have half the amount of cytoplasm and half the amount of DNA. B) The daughter cells have half the number of chromosomes and half the amount of DNA. C) The daughter cells have the same number of chromosomes and half the amount of DNA. D) The daughter cells have the same number of chromosomes and the same amount of DNA. E) The daughter cells have the same number of chromosomes and twice the amount of DNA.
28) The formation of a cell plate is beginning across the middle of a cell and nuclei are re-forming at opposite ends of the cell. What kind of cell is this? A) an animal cell in metaphase B) an animal cell in telophase C) an animal cell undergoing cytokinesis D) a plant cell in metaphase E) a plant cell undergoing cytokinesis 29) Taxol is an anticancer drug extracted from the Pacific yew tree. In animal cells, taxol disrupts microtubule formation by binding to microtubules and accelerating their assembly from the protein precursor, tubulin. Surprisingly, this stops mitosis. Specifically, taxol must affect A) the fibers of the mitotic spindle. B) anaphase. C) formation of the centrioles. D) chromatid assembly. E) the S phase of the cell cycle. 30) Which of the following are primarily responsible for cytokinesis in plant cells? A) kinetochores B) Golgi-derived vesicles C) actin and myosin D) centrioles and basal bodies E) cyclin-dependent kinases
31) Which of the following organisms does not reproduce cells by mitosis and cytokinesis? A) cow B) bacterium C) mushroom D) cockroach E) banana tree
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32) Chromosomes first become visible during ________ of mitosis. A) prometaphase B) telophase C) prophase D) metaphase E) anaphase
33) The correct sequence of steps in the M phase of the cell cycle is A) prophase, prometaphase, metaphase, anaphase, telophase. B) prophase, metaphase, prometaphase, anaphase, telophase. C) prophase, prometaphase, metaphase, anaphase, telophase, cytokinesis. D) prophase, metaphase, anaphase, telophase, cytokinesis. E) cytokinesis, telophase, prophase, metaphase, prometaphase, anaphase.
34) During which phases of mitosis are chromosomes composed of two chromatids? A) from interphase through anaphase B) from G1 of interphase through metaphase C) from metaphase through telophase D) from anaphase through telophase E) from G2 of interphase through metaphase
35) Which of the following is false regarding the bacterial chromosome? A) It consists of a single, circular DNA molecule. B) DNA replication begins at the origin of replication. C) Its centromeres uncouple during metaphase of mitosis. D) It is highly folded within the cell. E) It has genes that control binary fission. 36) In which group of eukaryotic organisms does the nuclear envelope remain intact during mitosis? A) seedless plants B) dinoflagellates C) diatoms D) B and C only E) A, B, and C
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37) Movement of the chromosomes during anaphase would be most affected by a drug that A) reduces cyclin concentrations. B) increases cyclin concentrations. C) prevents elongation of microtubules. D) prevents shortening of microtubules. E) prevents attachment of the microtubules to the kinetochore. 38) Measurements of the amount of DNA per nucleus were taken on a large number of cells from a growing fungus. The measured DNA levels ranged from 3 to 6 picograms per nucleus. In which stage of the cell cycle was the nucleus with 6 picograms of DNA? A) G0 B) G 1 C) S D) G2 E) M 39) A group of cells is assayed for DNA content immediately following mitosis and is found to have an average of 8 picograms of DNA per nucleus. Those cells would have ________ picograms at the end of the S phase and ________ picograms at the end of G2. A) 8; 8 B) 8; 16 C) 16; 8 D) 16; 16 E) 12; 16 40) The somatic cells derived from a single-celled zygote divide by which process? A) meiosis B) mitosis C) replication D) cytokinesis alone E) binary fission 41) Cytoskeletal elements play important roles in cell division. The mitotic spindle apparatus is made of ________ and pulls sister chromatids apart, whereas the contractile ring is made of ________ and required for the separation of daughter cells at the end of the mitotic phase of the cell cycle. A) intermediate filaments; actin microfilaments B) microtubules; actin microfilaments C) microtubules; contractile filaments D) intermediate filaments; contractile filaments E) actin microfilaments; myosin 42) Imagine looking through a microscope at a squashed onion root tip. The chromosomes of many of the cells are plainly visible. In some cells, replicated chromosomes are aligned along the center (equator) of the cell. These particular cells are in which stage of mitosis? A) telophase B) prophase C) anaphase D) metaphase E) prometaphase 43) If mammalian cells receive a go-ahead signal at the G1 checkpoint, they will A) move directly into telophase. B) complete the cycle and divide. C) exit the cycle and switch to a nondividing state. D) show a drop in MPF concentration.
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E) complete cytokinesis and form new cell walls. 44) Cells that are in a nondividing state are in which phase? A) G0 B) G 2 C) G 1 D) S E) M
45) What causes the decrease in the amount of cyclin at a specific point in the cell cycle? A) an increase in production once the restriction point is passed B) the cascade of increased production once its protein is phosphorylated by Cdk C) the changing ratio of cytoplasm to genome D) its destruction by a process initiated by the activity of MPF complexes E) the binding of PDGF to receptors on the cell surface
The following questions consist of five phrases or sentences related to the control of cell division. For each one, select the term below that is most closely related to it. Each term may be used once, more than once, or not at all. A. B. C. D. E. PDGF MPF protein kinase cyclin Cdk
46) released by platelets in the vicinity of an injury 47) a general term for enzymes that activate or inactivate other proteins by phosphorylating them 48) Fibroblasts have receptors for this substance on their plasma membranes.
49) a protein synthesized at specific times during the cell cycle that associates with a kinase to form a catalytically active complex
50) a protein maintained at constant levels throughout the cell cycle that requires cyclin to become catalytically active
51) triggers the cell's passage past the G2 checkpoint into mitosis
The questions below consist of five phrases or sentences concerned with the cell cycle. For each one, select the answer below that is most closely related to it. Each answer may be used once, more than once, or not at all. A. B. C. D. G0 G1 S G2
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E.
M
52) The "restriction point" occurs here. 53) Nerve and muscle cells are in this phase. 54) the shortest part of the cell cycle
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55) DNA is replicated at this time of the cell cycle. 56) The cyclin component of MPF is destroyed toward the end of this phase. The following questions are based on Figure 12.3.
Figure 12.3 57) In the figure above, mitosis is represented by which number? A) I B) II C) III D) IV E) V
58) MPF reaches its threshold concentration at the end of this stage. A) I B) II C) III D) IV E) V 59) G1 is represented by which number(s)? A) I and V B) II and IV C) III D) IV E) V 60) Which number represents DNA synthesis? A) I B) II C) III D) IV E) V 61) Which number represents the point in the cell cycle during which the chromosomes are replicated? A) I B) II C) III
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D) IV E) V 62) What is the name of enzymes that control the activities of other proteins by phosphorylating them? A) ATPases B) kinases C) cyclins D) chromatin E) protein kinases 63) An enzyme that attaches a phosphate group to another molecule is called a A) phosphatase. B) phosphorylase. C) kinase. D) cyclase. E) ATPase. 64) Proteins that are involved in the regulation of the cell cycle, and that show fluctuations in concentration during the cell cycle, are called A) ATPases. B) kinetochores. C) centrioles. D) proton pumps. E) cyclins.
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65) The MPF protein complex turns itself off by A) activating a process that destroys cyclin. B) activating an enzyme that stimulates cyclin. C) binding to chromatin. D) exiting the cell. E) activating the anaphase-promoting complex. 66) A mutation results in a cell that no longer produces a normal protein kinase for the M phase checkpoint. Which of the following would likely be the immediate result of this mutation? A) The cell would prematurely enter anaphase. B) The cell would never leave metaphase. C) The cell would never enter metaphase. D) The cell would never enter prophase. E) The cell would undergo normal mitosis, but fail to enter the next G1 phase. 67) Density-dependent inhibition is explained by which of the following? A) As cells become more numerous, they begin to squeeze against each other, restricting their size and ability to produce control factors. B) As cells become more numerous, the amount of required growth factors and nutrients per cell becomes insufficient to allow for cell growth. C) As cells become more numerous, the protein kinases they produce begin to compete with each other, such that the proteins produced by one cell essentially cancel those produced by its neighbor. D) As cells become more numerous, more and more of them enter the S phase of the cell cycle. E) As cells become more numerous, the level of waste products increases, eventually slowing down metabolism. 68) Which of the following is true concerning cancer cells? A) They do not exhibit density-dependent inhibition when growing in culture. B) When they stop dividing, they do so at random points in the cell cycle. C) They are not subject to cell cycle controls. D) B and C only E) A, B, and C
69) 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 groups to other proteins. D) Both A and B are true. E) Both B and C are true.
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70) A particular cyclin called cyclin E forms a complex with a cyclin-dependent kinase called Cdk 2. This complex is important for the progression of the cell from G1 into the S phase of the cell cycle. Which of the following statements is correct? A) The amount of cyclin E is greatest during the S phase. B) The amount of Cdk 2 is greater during G1 compared to the S phase. C) The amount of cyclin E is highest during G1. D) The amount of Cdk 2 is greatest during G1. E) The activity of the cyclin E/Cdk 2 complex is highest during G2.
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