Biology 2014 Chapter 9

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1) Starting with a fertilized egg (zygote), a series of five cell divisions would produce an early embryo with how many cells?

D) 32

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2) If there are 20 chromatids in a cell, how many centromeres are there?

B) 20

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3) In eukaryotic cells, chromosomes are composed of DNA

C) and proteins.

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4) What is produced if a cell divides by mitosis but does not undergo cytokinesis?

D) one cell with two nuclei, each identical to the nucleus of the parent cell

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5) Humans produce skin cells by mitosis and gametes by meiosis. The nuclei of skin cells produced by mitosis will have

C) twice as much DNA as the nuclei of gametes produced by meiosis.

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6) Compared to most prokaryotic cells, eukaryotic cells typically have

A) more DNA molecules and larger genomes.

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7) At which phase are centrioles beginning to move apart in animal cells?

E) prophase

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8) If there are 20 centromeres in a cell at anaphase, how many chromosomes are there in each daughter cell following cytokinesis?

A) 10

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9) Where do the microtubules of the spindle originate during mitosis in animal cells?

B) centrosome

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10) 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 formation of the mitotic spindle.

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11) Which of the following are primarily responsible for cytokinesis in plant cells but not in animal cells?

B) Golgi-derived vesicles

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12) Movement of the chromosomes during anaphase would be most affected by a drug that prevents

D) shortening of microtubules.

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13) 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 did the nucleus contain 6 picograms of DNA?

D) G2

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14) 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. How many picograms would be found at the end of S and the end of G2?

D) 16; 16

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15) The beginning of anaphase is indicated by which of the following?

C) Cohesin is cleaved enzymatically.

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16) During which phase of mitosis do the chromatids become chromosomes?

B) Anaphase

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17) What is a cleavage furrow?

C) a groove in the plasma membrane between daughter nuclei

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18) Using which of the following techniques would enable your lab group to distinguish between a cell in G2 and a cell from the same organism in G1?

D) radioactive-labeled nucleotides

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19) You have the technology necessary to measure each of the following in a sample of animal cells: chlorophylls, organelle density, picograms of DNA, cell wall components, and enzymatic activity. Which would you expect to increase significantly from M to G1?

A) organelle density and enzymatic activity

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20) A plant-derived protein known as colchicine can be used to poison cells by blocking the formation of the spindle. Which of the following would result if colchicine is added to a sample of cells in G2?

C) The chromosomes would coil and shorten but have no spindle to which to attach.

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21) Motor proteins require which of the following to function in the movement of chromosomes toward the poles of the mitotic spindle?

D) ATP as an energy source

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22) When a cell is in late anaphase of mitosis, which of the following will we see?

A) a clear area in the center of the cell

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23) Cells from advanced malignant tumors often have very abnormal chromosomes as well as an abnormal number of chromosomes. What might explain the association between malignant tumors and chromosomal abnormalities?

C) Cell cycle checkpoints are not in place to stop cells with chromosome abnormalities.

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24) Which is the first checkpoint in the cell cycle where a cell will be caused to exit the cycle if this point is not passed?

B) G1

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25) Which of the following is released by platelets in the vicinity of an injury?

A) PDGF

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26) Which of the following is a protein synthesized at specific times during the cell cycle that associates with a kinase to form a catalytically active complex?

D) cyclin

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27) Which of the following is a protein maintained at constant levels throughout the cell cycle that requires cyclin to become catalytically active?

E) Cdk

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28) Which of the following triggers the cell's passage past the G2 checkpoint into mitosis?

B) MPF

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29) The cyclin component of MPF is destroyed toward the end of which phase?

E) M

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30) Proteins that are involved in the regulation of the cell cycle, and that show fluctuations in concentration during the cell cycle, are called

E) cyclins.

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31) The MPF protein complex turns itself off by

A) activating a process that destroys cyclin components.

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32) Density-dependent inhibition is explained by which of the following?

B) As cells become more numerous, the cell surface proteins of one cell contact the adjoining cells and they stop dividing.

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33) Which of the following is true concerning cancer cells?

E) When they stop dividing, they do so at random points in the cell cycle; they are not subject to cell cycle controls; and they do not exhibit density-dependent inhibition when growing in culture.

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34) Which of the following describes cyclin-dependent kinase (Cdk)?

E) Cdk is present throughout the cell cycle and is an enzyme that attaches phosphate groups to other proteins.

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35) Besides the ability of some cancer cells to overproliferate, what else could logically result in a tumor?

C) lack of appropriate cell death

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36) Why do neurons and some other specialized cells divide infrequently?

C) They have been shunted into G0.

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37) Which of the following most accurately describes a cyclin?

D) It activates a Cdk molecule when it is in sufficient concentration.

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38) All cell cycle checkpoints are similar in which way?

C) They give the go-ahead signal to progress to the next checkpoint.

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39) At the M phase checkpoint, the complex allows for what to occur?

A) Separase enzyme cleaves cohesins and allows chromatids to separate.

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40) Anchorage dependence of animal cells in vitro or in vivo depends on which of the following?

B) response of the cell cycle controls to signals from the plasma membrane

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41) Researchers began a study of a cultured cell line. Their preliminary observations showed them that the cell line did not exhibit either density-dependent inhibition or anchorage dependence. What could they conclude right away?

D) The cells show characteristics of tumors.

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42) For a chemotherapeutic drug to be useful for treating cancer cells, which of the following is most desirable?

E) It interferes with rapidly dividing cells.

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43) You have a series of cells, all of which were derived from tumors, and you first need to find out which ones are malignant. What could you do?

C) Karyotype samples to look for unusual size and number of chromosomes.

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Several organisms, primarily protists, have what are called intermediate mitotic organization.

1) These protists are intermediate in what sense?

D) They maintain a nuclear envelope during division.

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2) What is the most probable hypothesis about these intermediate forms of cell division?

E) They show some but not all of the evolutionary steps toward complete mitosis.

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Nucleotides can be radiolabeled before they are incorporated into newly forming DNA and can therefore be assayed to track their incorporation. In a set of experiments, a student-faculty research team used labeled T nucleotides and introduced these into the culture of dividing human cells at specific times.

3) Which of the following questions might be answered by such a method?

B) What is the length of the S phase of the cell cycle?

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Nucleotides can be radiolabeled before they are incorporated into newly forming DNA and can therefore be assayed to track their incorporation. In a set of experiments, a student-faculty research team used labeled T nucleotides and introduced these into the culture of dividing human cells at specific times.

4) The research team used the setup to study the incorporation of labeled nucleotides into a culture of lymphocytes and found that the lymphocytes incorporated the labeled nucleotide at a significantly higher level after a pathogen was introduced into the culture. They concluded that

C) infection causes lymphocytes to divide more rapidly.

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1) Through a microscope, you can see a cell plate beginning to develop across the middle of a cell and nuclei forming on either side of the cell plate. This cell is most likely

B) a plant cell in the process of cytokinesis.

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2) In the cells of some organisms, mitosis occurs without cytokinesis. This will result in

A) cells with more than one nucleus.

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3) Which of the following does not occur during mitosis?

B) replication of the DNA

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4) A particular cell has half as much DNA as some other cells in a mitotically active tissue. The cell in question is most likely in

A) G1.

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5) The drug cytochalasin B blocks the function of actin. Which of the following aspects of the animal cell cycle would be most disrupted by cytochalasin B?

E) cleavage furrow formation and cytokinesis