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

The drug cytochalasin B blocks the function of actin. Which of the following aspects of the 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





Answer: E

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 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.




Answer: A

Which of the following does not occur during mitosis?

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


Answer: B

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

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.





Answer: A

The decline of MPF activity at the end of mitosis is due to

The decline of MPF activity at the end of mitosis is due to 

A) the destruction of the protein kinase Cdk.
B) decreased synthesis of Cdk.
C) the degradation of cyclin.
D) the accumulation of cyclin.
E) synthesis of DNA.






Answer: C

One difference between cancer cells and normal cells is that cancer cells

One difference between cancer cells and normal cells is that cancer cells 

A) are unable to synthesize DNA.
B) are arrested at the S phase of the cell cycle.
C) continue to divide even when they are tightly packed together.
D) cannot function properly because they are affected by density-dependent inhibition.
E) are always in the M phase of the cell cycle.





Answer: C

Vinblastine is a standard chemotherapeutic drug used to treat cancer. Because it interferes with the assembly of microtubules, its effectiveness must be related to

Vinblastine is a standard chemotherapeutic drug used to treat cancer. Because it interferes with the assembly of microtubules, its effectiveness must be related to 

A) disruption of mitotic spindle formation.
B) inhibition of regulatory protein phosphorylation.
C) suppression of cyclin production.
D) myosin denaturation and inhibition of cleavage furrow formation.
E) inhibition of DNA synthesis.




Answer: A

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

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.




Answer: B

A student is looking through his light microscope (~450 X) at a squashed and stained onion root tip. Some, but not all, of the cells have clearly visible chromosome strands.

When a cell is in anaphase of mitosis, which of the following will he see? 

A) a clear area in the center of the cell
B) chromosomes clustered at the poles
C) individual chromatids separating
D) chromosomes clustered tightly at the center
E) formation of vesicles at the midline

Answer: A

When the cell has just completed telophase, which of the following does he see? 

A) a clear area in the center of the cell
B) chromosomes clustered at the poles
C) individual chromatids separating
D) formation of vesicles at the midline
E) two small cells with chromatin

Answer: E

The research team established similar lymphocyte cultures from a number of human donors, including healthy teenagers of both genders, patients already suffering from long-term bacterial infections, and elderly volunteers. They found that the increase in lymphocyte incorporation after pathogen introduction was slightly lower in some of the female teenagers and significantly lower in each of the elderly persons. They repeated the study with a larger number of samples but got the same results.

What might be among the research team's conclusions? 

A) The young women showed these results because they have poorer nutrition.
B) The elderly persons' samples demonstrated their lowered immune responses.
C) The young men had higher responses because they are generally healthier.
D) The patient samples should have had the lowest response but did not, so the experiment is invalid.
E) The elderly donor samples represent cells no longer capable of any cell division.


Answer: B

Which of the following investigations might be most productive to show what the data on the teenagers might indicate? 

A) test male teenagers
B) test teenagers who say they are not sexually active
C) test female teens at different times in their menstrual cycles
D) test relatives of the teens previously tested
E) test teenagers from different school systems

Answer: C

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?


Answer: B

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.


Answer: C

Once they had determined which cells were dividing, the team wanted to use a non-radioactive method to track whether various physiological factors (such as food or body temperature) affect the action of the pathogen. Which of the following would be effective, simple, and safe? 

A) measuring picograms of DNA
B) measuring numbers of chromosomes
C) measuring numbers of chromatids
D) counting the frequency of cells in mitosis
E) counting newly formed plasma membranes



Answer: D

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

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.

Answer: D

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

A) They represent a form of cell reproduction which 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.



Answer: E

MPF reaches its threshold concentration at the end of this stage.

MPF reaches its threshold concentration at the end of this stage. 

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






Answer: C

At which of the numbered regions would you expect to find cells at metaphase?

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


Answer: C

Which number represents the point in the cell cycle during which the chromosomes are replicated?

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





Answer: B

Which number represents DNA synthesis?

Which number represents DNA synthesis? 

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





Answer: B

G1 is represented by which numbered part(s) of the cycle?

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





Answer: A

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?

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



Answer: D

What is the correct chromosomal condition at the prometaphase of mitosis?

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.

What is the correct chromosomal condition at the prometaphase of mitosis? 

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




Answer: B

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?

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 over proliferating.
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.




Answer: C