Deck 9: The Cell Cycle

Question 1

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

A) nuclear envelope breakdown.
B) cell wall formation.
C) elongation of microtubules.
D) shortening of microtubules.
E) formation of a cleavage furrow.

Answer 1

D

Question 2

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?

A) 8; 8
B) 8; 16
C) 16; 8
D) 16; 16
E) 12; 16

Answer 2

D

Question 3

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

A) telophase
B) anaphase
C) prometaphase
D) metaphase
E) prophase

Answer 3

E

Question 4

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

A) 10
B) 20
C) 30
D) 40
E) 80

Question 5

During which phase of mitosis do the chromatids become chromosomes?

A) telophase
B) anaphase
C) prophase
D) metaphase
E) cytokinesis

Question 6

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

A) two cells, one cell containing two nuclei and a second cell without a nucleus
B) two cells, each cell with half of the genetic material of the parent cell
C) one cell with one nucleus containing half of the genetic material of the parent cell
D) one cell with two nuclei, each identical to the nucleus of the parent cell

Question 7

Compared to most prokaryotic cells, eukaryotic cells typically have

A) more DNA molecules and larger genomes.
B) the same number of DNA molecules but larger genomes.
C) the same number of DNA molecules and similarly sized genomes.
D) fewer DNA molecules but larger genomes.
E) fewer DNA molecules and smaller genomes.

Question 8

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?

A) fluorescence microscopy
B) electron microscopy
C) spectrophotometry
D) radioactive-labeled nucleotides
E) labeled kinetochore proteins

Question 9

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

A) kinetochores
B) Golgi-derived vesicles
C) actin and myosin
D) centrioles and centromeres
E) tubulin and dynein

Question 10

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

Question 11

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.
B) anaphase.
C) formation of the centrioles.
D) chromatid assembly.
E) the S phase of the cell cycle.

Question 12

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?

A) G0
B) G1
C) S
D) G2
E) M

Question 13

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

A) Chromatids lose their kinetochores.
B) Cohesin attaches the sister chromatids to each other.
C) Cohesin is cleaved enzymatically.
D) Kinetochores attach to the metaphase plate.
E) Spindle microtubules begin to polymerize.

Question 14

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

A) centromere
B) centrosome
C) centriole
D) chromatid
E) kinetochore

Question 15

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?

A) The cells would immediately die.
B) The cells would be unable to begin M and stay in G2.
C) The chromosomes would coil and shorten but have no spindle to which to attach.
D) The chromosomes would segregate but in a disorderly pattern.
E) Each resultant daughter cell would also be unable to form a spindle.

Question 16

What is a cleavage furrow?

A) a ring of vesicles forming a cell plate
B) the separation of divided prokaryotes
C) a groove in the plasma membrane between daughter nuclei
D) the metaphase plate where chromosomes attach to the spindle
E) the space that is created between two chromatids during anaphase

Question 17

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

Question 18

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

A) half as much DNA as the nuclei of gametes produced by meiosis.
B) the same amount of DNA as the nuclei of gametes produced by meiosis.
C) twice as much DNA as the nuclei of gametes produced by meiosis.
D) four times as much DNA as the nuclei of gametes produced by meiosis.

Question 19

In eukaryotic cells, chromosomes are composed of DNA

A) and RNA.
B) only.
C) and proteins.
D) and phospholipids.

Question 20

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
B) cell wall components and DNA
C) chlorophyll and cell walls
D) organelle density and cell walls
E) chlorophyll and DNA

Question 21

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?

A) Cancer cells are no longer density dependent.
B) Cancer cells are no longer anchorage dependent.
C) Cell cycle checkpoints are not in place to stop cells with chromosome abnormalities.
D) Chromosomally abnormal cells still have normal metabolism.
E) Transformation introduces new chromosomes into cells.

Question 22

Which of the following most accurately describes a cyclin?

A) It is present in similar concentrations throughout the cell cycle.
B) It is activated to phosphorylate by complexing with a Cdk.
C) It decreases in concentration when MPF activity increases.
D) It activates a Cdk molecule when it is in sufficient concentration.
E) It activates a Cdk when its concentration is decreased.

Question 23

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
B) chromosomes clustered at the poles
C) individual chromatids beginning to separate from one another
D) chromosomes clustered tightly at the center
E) breaking down of the nuclear envelope

Question 24

All cell cycle checkpoints are similar in which way?

A) They respond to the same cyclins.
B) They utilize the same Cdks.
C) They give the go-ahead signal to progress to the next checkpoint.
D) They each have only one cyclin/Cdk complex.
E) They activate or inactivate other proteins.

Question 25

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?

A) G0
B) G1
C) G2
D) S
E) previous M

Question 26

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) kinases.
D) estrogen receptors.
E) cyclins.

Question 27

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) When they stop dividing, they do so at random points in the cell cycle, and they are not subject to cell cycle controls.
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.

Question 28

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

A) PDGF
B) MPF
C) protein kinase
D) cyclin
E) Cdk

Question 29

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

A) attachment of spindle fibers to centrioles
B) response of the cell cycle controls to signals from the plasma membrane
C) the absence of an extracellular matrix
D) the binding of cell-surface phospholipids to those of adjoining cells
E) the binding of cell-surface phospholipids to the substrate

Question 30

Why do neurons and some other specialized cells divide infrequently?

A) They no longer have active nuclei.
B) They no longer carry receptors for signal molecules.
C) They have been shunted into G0.
D) They can no longer bind Cdk to cyclin.
E) They show a drop in MPF concentration.

Question 31

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

A) Separase enzyme cleaves cohesins and allows chromatids to separate.
B) Cohesins alter separase to allow chromatids to separate.
C) Kinetochores are able to bind to spindle microtubules.
D) All microtubules are made to bind to kinetochores.
E) Daughter cells are allowed to pass into G1.

Question 32

Which of the following describes 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) Cdk is inactive, or "turned off," in the presence of cyclin and it is present throughout the cell cycle.
E) Cdk is present throughout the cell cycle and is an enzyme that attaches phosphate groups to other proteins.

Question 33

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?

A) PDGF
B) MPF
C) protein kinase
D) cyclin
E) Cdk

Question 34

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

A) intact centromeres
B) a microtubule-organizing center
C) a kinetochore attached to the metaphase plate
D) ATP as an energy source
E) synthesis of cohesin

Question 35

The MPF protein complex turns itself off by

A) activating a process that destroys cyclin components.
B) activating an enzyme that stimulates cyclin.
C) binding to chromatin.
D) exiting the cell.
E) activating the anaphase-promoting complex.

Question 36

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 cell surface proteins of one cell contact the adjoining cells and they stop dividing.
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.

Question 37

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

A) PDGF
B) MPF
C) protein kinase
D) cyclin
E) Cdk

Question 38

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

A) PDGF
B) MPF
C) protein kinase
D) cyclin
E) Cdk

Question 39

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

A) G0
B) G1
C) S
D) G2
E) M

Question 40

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

A) enhanced anchorage dependence
B) changes in the order of cell cycle stages
C) lack of appropriate cell death
D) inability to form spindles
E) inability of chromosomes to meet at the metaphase plate

Question 41

Use the following information to answer the questions below.
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.
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

A) an animal cell in the process of cytokinesis.
B) a plant cell in the process of cytokinesis.
C) an animal cell in the S phase of the cell cycle.
D) a bacterial cell dividing.
E) a plant cell in metaphase.

Question 42

Use the following information to answer the questions below.
The unlettered circle at the top of Figure 9.1 shows a diploid nucleus with four chromosomes that have not yet replicated. There are two pairs of homologous chromosomes, one long and the other short. One haploid set is black, and the other is gray. The circles labeled A-E show various combinations of these chromosomes. Figure 9.1
What is the correct chromosomal condition for one daughter nucleus at telophase of mitosis?

A) A
B) B
C) C
D) D
E) E

Question 43

The following questions are based on Figure 9.3.
Figure 9.3
MPF reaches its threshold concentration at the end of this stage.

A) I
B) II
C) III
D) IV
E) V

Question 44

Use the data in Table 9.1 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 9.1
Minutes Spent in Cell Cycle Phases
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.

Question 45

Use the following information to answer the questions below.
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.
Which of the following questions might be answered by such a method?

A) How many cells are produced by the culture per hour?
B) What is the length of the S phase of the cell cycle?
C) When is the S chromosome synthesized?
D) How many picograms of DNA are made per cell cycle?
E) When do spindle fibers attach to chromosomes?

Question 46

The following questions are based on Figure 9.3.
Figure 9.3
At which of the numbered regions would you expect to find cells at metaphase?

A) I and IV
B) II only
C) III only
D) IV only
E) V only

Question 47

Use the following information to answer the questions below.
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.
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

A) the presence of the pathogen made the experiment too contaminated to trust the results.
B) their tissue culture methods needed to be relearned.
C) infection causes lymphocytes to divide more rapidly.
D) infection causes cell cultures in general to reproduce more rapidly.
E) infection causes lymphocyte cultures to skip some parts of the cell cycle.

Question 48

The following information applies to the questions below.
Several organisms, primarily protists, have what are called intermediate mitotic organization.
What is the most probable hypothesis about these intermediate forms of cell division?

A) They represent a form of cell reproduction that must have evolved completely separately from those of other organisms.
B) They demonstrate that these species are not closely related to any of the other protists and may well be a different kingdom.
C) They rely on totally different proteins for the processes they undergo.
D) They may be more closely related to plant forms that also have unusual mitosis.
E) They show some but not all of the evolutionary steps toward complete mitosis.

Question 49

Use the following information to answer the questions below.
The unlettered circle at the top of Figure 9.1 shows a diploid nucleus with four chromosomes that have not yet replicated. There are two pairs of homologous chromosomes, one long and the other short. One haploid set is black, and the other is gray. The circles labeled A-E show various combinations of these chromosomes. Figure 9.1
What is the correct chromosomal condition for one daughter nucleus at telophase of mitosis?

A) A
B) B
C) C
D) D
E) E

Question 50

The following information applies to the questions below.
Several organisms, primarily protists, have what are called intermediate mitotic organization.
These protists are intermediate in what sense?

A) They reproduce by binary fission in their early stages of development and by mitosis when they are mature.
B) They never coil up their chromosomes when they are dividing.
C) They use mitotic division but only have circular chromosomes.
D) They maintain a nuclear envelope during division.
E) None of them form spindles.

Question 51

Use the following information to answer the questions below.
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.
In the cells of some organisms, mitosis occurs without cytokinesis. This will result in

A) cells with more than one nucleus.
B) cells that are unusually small.
C) cells lacking nuclei.
D) destruction of chromosomes.
E) cell cycles lacking an S phase.

Question 52

The following questions are based on Figure 9.3.
Figure 9.3
G1 is represented by which numbered part(s) of the cycle?

A) I or V
B) II or IV
C) III only
D) IV only
E) V only

Question 53

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

A) It is safe enough to limit all apoptosis.
B) It does not alter metabolically active cells.
C) It only attacks cells that are density dependent.
D) It interferes with cells entering G0.
E) It interferes with rapidly dividing cells.

Question 54

The following questions are based on Figure 9.3.
Figure 9.3
Which number represents the point in the cell cycle during which the chromosomes are replicated?

A) I
B) II
C) III
D) IV
E) V

Question 55

The following questions are based on Figure 9.3.
Figure 9.3
In Figure 9.3, mitosis is represented by which numbered part(s) of the cycle?

A) I
B) II
C) III
D) IV
E) V

Question 56

Use the data in Table 9.1 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 9.1
Minutes Spent in Cell Cycle Phases
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 cells reproduce asexually.
D) gamma contains 48 times more DNA and RNA than beta.
E) beta is a plant cell and gamma is an animal cell.

Question 57

The following questions are based on Figure 9.3.
Figure 9.3
Which number represents DNA synthesis?

A) I
B) II
C) III
D) IV
E) V

Question 58

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?

A) The cells originated in the nervous system.
B) The cells are unable to form spindle microtubules.
C) The cells have altered series of cell cycle phases.
D) The cells show characteristics of tumors.
E) The cells were originally derived from an elderly organism.

Question 59

Figure 9.2
If the cell whose nuclear material is shown in Figure 9.2 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

Question 60

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?

A) See which ones are not overproliferating.
B) Find out which ones have a higher rate of apoptosis.
C) Karyotype samples to look for unusual size and number of chromosomes.
D) Measure metastasis.
E) Time their cell cycles.

Question 61

Use the following information to answer the questions below.
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.
Which of the following does not occur during mitosis?

A) condensation of the chromosomes
B) replication of the DNA
C) separation of sister chromatids
D) spindle formation
E) separation of the spindle poles

Question 62

Use the following information to answer the questions below.
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.
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.
B) G2.
C) prophase.
D) metaphase.
E) anaphase.

Question 63

Use the following information to answer the questions below.
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.
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?

A) spindle formation
B) spindle attachment to kinetochores
C) DNA synthesis
D) cell elongation during anaphase
E) cleavage furrow formation and cytokinesis