Deck 9: The Cell Cycle

Question 1

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

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

Answer 1

B

Question 2

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

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

Answer 2

E

Question 3

At which phase of mitosis do the sister chromatids become daughter chromosomes?

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

Answer 3

D

Question 4

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 would the nucleus contain 6 picograms of DNA?

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

Question 5

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 6

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

A) 5
B) 10
C) 20
D) 40

Question 7

Taxol is an anticancer drug extracted from the Pacific yew tree that binds to microtubules and prevents their depolymerization. Actively dividing cells treated with Taxol become blocked in which phase of mitosis?

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

Question 8

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

A) loss of kinetochores from sister chromatids
B) enzymatic cleavage of cohesin
C) joining of the sister chromatids to each other by cohesin
D) polymerization of spindle microtubules

Question 9

A cell in G2 of the cell division cycle contains 20 chromatids. How many centromeres are present in this cell?

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

Question 10

A group of cells is assayed for DNA content immediately before beginning mitosis and is found to have an average of 16 picograms of DNA per nucleus. How many picograms would be in a cell nucleus following completion of mitosis and cytokinesis?

A) 4
B) 8
C) 16
D) 32

Question 11

What is produced if a cell completes 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) two cells, each cell with an identical nucleus containing the genetic material of the parent cell
D) one cell with one nucleus containing half of the genetic material of the parent cell
E) one cell with two nuclei, each identical to the nucleus of the parent cell

Question 12

Beginning 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 13

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 14

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 segregate but in a disorderly pattern.
D) Chromosome condensation would occur, but the chromosomes would fail to align at the metaphase plate.

Question 15

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 16

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.

Question 17

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

Question 18

During mitosis in animal cells, at which phase do centrioles begin to move apart?

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

Question 19

What is a cleavage furrow?

A) a ring of vesicles forming a cell plate
B) an indentation between daughter prokaryotic cells
C) a groove in the plasma membrane between daughter nuclei
D) the metaphase plate where chromosomes attach to the spindle

Question 20

Eukaryotic chromatin is composed of

A) condensed DNA only.
B) DNA and RNA.
C) DNA and carbohydrates.
D) DNA and proteins.
E) DNA and ribosomes.

Question 21

Most animal cells exhibit anchorage dependence, which means that in order to divide

A) all chromosomes must be attached to spindle microtubules.
B) nonkinetochore microtubules from opposite poles must overlap and be attached by motor proteins.
C) cell-surface phospholipids must be attached to those of adjoining cells.
D) cells must be attached to a substrate or extracellular matrix of a tissue.

Question 22

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) M

Question 23

Which of the following is true concerning cancer cells?

A) They exhibit density-dependent inhibition when growing in culture.
B) They must be attached to a substrate to divide in culture.
C) They evade the normal controls that trigger programmed cell death.
D) They stop dividing in culture when growth factors are depleted.

Question 24

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) alignment of chromosomes at the metaphase plate
C) segregation of daughter chromosomes toward the poles
D) formation of telophase nuclei
E) synthesis of sister chromatids

Question 25

Please use the following information to answer the question(s) 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 a nucleus at prophase of mitosis?

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

Question 26

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 show characteristics of tumors.
C) The cells have altered series of cell cycle phases.
D) The cells were originally derived from an elderly organism.

Question 27

When a cell is in late anaphase of mitosis, which of the following may be seen?

A) a clear area in the center of the dividing cell
B) decondensing chromosomes clustered at the poles
C) individual chromatids beginning to separate from one another
D) chromosomes clustered tightly at the center of the dividing cell
E) nuclear envelopes forming at the poles

Question 28

Please use the following information to answer the question(s) 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 a nucleus in G1 of the cell division cycle?

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

Question 29

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 growth factors.
B) 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.
C) As cells become more numerous, the cell surface proteins of adjacent cells bind to each other and send signals that inhibit cell division.
D) As cells become more numerous, the level of waste products increases, eventually slowing down metabolism.

Question 30

The protein complex that activates progress through the M phase checkpoint will allow which of the following to occur?

A) cleavage of cohesin proteins by separase
B) modification of separase by cohesins
C) disassembly of spindle microtubules at the centromere
D) assembly of spindle microtubules

Question 31

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 no longer produce cyclins.

Question 32

Diatoms and some yeasts are unicellular eukaryotes that have mechanisms of nuclear division that may resemble intermediate steps in the evolution of mitosis. Which of the following is a characteristic feature of nuclear division in these organisms?

A) They have circular chromosomes that are segregated by attachment to the plasma membrane.
B) They have circular chromosomes that are segregated by attachment to spindle microtubules.
C) Chromosomes are not condensed during nuclear division.
D) The nuclear envelope remains intact during division.

Question 33

Cells from advanced malignant tumors frequently 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 replicate chromosomes multiple times per cell cycle.
B) Cancer cells are no longer anchorage dependent.
C) Cell cycle checkpoints are not in place to stop cells with chromosome abnormalities.
D) Cells with abnormal chromosomes have increased metabolism.

Question 34

You have a series of cells, all of which were derived from tumors. How might you determine which ones are malignant?

A) Identify the ones that are not dividing uncontrollably.
B) Identify the ones with higher rates of apoptosis.
C) Prepare karyotypes to identify the ones with aberrant chromosome number or structure.
D) Identify the ones with elongated cell cycles.

Question 35

Besides the ability of some cancer cells to divide uncontrollably, 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

Question 36

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 affect metabolically active cells.
C) It only attacks cells that are density dependent.
D) It targets only rapidly dividing cells.

Question 37

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

A) PDGF
B) separase
C) protein kinase
D) cyclin

Question 38

Please use the following information to answer the question(s) 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
Which image displays the chromosomal composition of one daughter nucleus at telophase of mitosis?

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

Question 39

The cell cycle is regulated at the molecular level by a set of proteins known as

A) ATPases.
B) separase proteins.
C) cohesins.
D) cyclins.

Question 40

Where are the motor proteins that move chromosomes toward the poles of the mitotic spindle located?

A) on the centrioles
B) in the centrosomes
C) on the kinetochores
D) along the length of kinetochore microtubules

Question 41

Please use the following information to answer the question(s) below.
The data in Table 9.1 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
Which of the following is the most plausible explanation for the difference in time spent in S phase by beta and gamma?

A) Gamma is unicellular and beta is multicellular.
B) Beta is tetraploid and gamma is diploid.
C) Gamma contains more DNA than beta.
D) Beta reproduces asexually and gamma reproduces sexually.
E) Beta is a plant cell and gamma is an animal cell.

Question 42

Please use the following information to answer the question(s) below.
The data in Table 9.1 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 only one chromosome that is very small.
C) are actually in the G0 phase.
D) synthesize DNA in the G1 phase

Question 43

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) a bacterial cell dividing.
D) a plant cell in metaphase.

Question 44

Figure 9.3
In Figure 9.3, G1 is represented by which numbered parts of the cycle?

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

Question 45

Figure 9.3
In Figure 9.3, G2 is represented by which numbered parts of the cycle?

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

Question 46

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) cell elongation during anaphase
D) cleavage furrow formation and cytokinesis

Question 47

Figure 9.3
In 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 48

Please use the following information to answer the question(s) below.
The data in Table 9.1 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
Several organisms, including a number of protists, have intermediate mitotic organization. Which of the following is the most probable hypothesis regarding 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

Please use the following information to answer the question(s) 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 introduced labeled T nucleotides 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 50

Please use the following information to answer the question(s) 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 introduced labeled T nucleotides 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 51

Figure 9.3
In Figure 9.3, mitosis is represented by which numbered parts of the cycle?

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

Question 52

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.

Question 53

Figure 9.3
In Figure 9.3, which of the numbered regions would contain cells at metaphase?

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

Question 54

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) cell cycles lacking an S phase.

Question 55

Figure 9.3
In Figure 9.3, DNA synthesis is represented by which numbered parts of the cycle?

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

Question 56

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