1. The centromere is a region in which
A) chromatids remain attached to one another until
anaphase.
B) metaphase chromosomes become aligned at the metaphase
plate.
C) chromosomes are grouped during telophase.
D) the nucleus is located prior to mitosis.
E) new spindle microtubules form at either end.
Answer: A
2. 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
Answer: D
3. If there are 20
chromatids in a cell, how many centromeres are there?
A) 10
B) 20
C) 30
D) 40
E) 80
Answer: A
4. For a newly evolving protist, what would be the
advantage of using eukaryote-like cell division rather than binary fission?
A) Binary fission would not allow for the formation of
new organisms.
B) Cell division would allow for the orderly and efficient
segregation of multiple linear chromosomes.
C) Cell division would be faster than binary fission.
D) Cell division allows for lower rates of error per
chromosome replication.
E) Binary fission would not allow the organism to have
complex cells.
Answer: B
5) Suppose a biologist can separate one of a dozen pieces
of chromatin from a eukaryotic (animal) nucleus. It might consist of which of
the following?
A) one-twelfth of the genes of the organism
B) two chromosomes, each with six chromatids
C) a single circular piece of DNA
D) two long strands of DNA plus proteins
E) two chromatids attached together at a centromere
Answer: D
6) At which phase are centrioles beginning to move apart
in animal cells?
A) telophase
B) anaphase
C) prometaphase
D) metaphase
E) prophase
Answer: E
7) If cells in the process of dividing are subjected to
colchicine, a drug that interferes with the formation of the spindle apparatus,
at which stage will mitosis be arrested?
A) anaphase
B) prophase
C) telophase
D) metaphase
E) interphase
Answer: D
8) 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
Answer: A
9) 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
Answer: B
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.
B) anaphase.
C) formation of the centrioles.
D) chromatid assembly.
E) the S phase of the cell cycle.
Answer: A
11) 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) cyclin-dependent kinases
Answer: B
12) In which group of eukaryotic organisms does the
nuclear envelope remain intact during mitosis?
A) seedless plants
B) dinoflagellates
C) diatoms
D) dinoflagellates and diatoms only
E) seedless plants, dinoflagellates, and diatoms
Answer: D
13) 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.
Answer: D
14) 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
Answer: D
15) 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: D
16) For anaphase to begin, which of the following must
occur?
A) Chromatids must lose their kinetochores.
B) Cohesin must attach the sister chromatids to each
other.
C) Cohesin must be cleaved enzymatically.
D) Kinetochores must attach to the metaphase plate.
E) Spindle microtubules must begin to depolymerize.
Answer: C
17) Why do chromosomes coil during mitosis?
A) to increase their potential energy
B) to allow the chromosomes to move without becoming
entangled and breaking
C) to allow the chromosomes to fit within the nuclear
envelope
D) to allow the sister chromatids to remain attached
E) to provide for the structure of the centromere
Answer: B
18) Which of the following best describes how chromosomes
move toward the poles of the spindle during mitosis?
A) The chromosomes are "reeled in" by the
contraction of spindle microtubules.
B) Motor proteins of the kinetochores move the
chromosomes along the spindle microtubules.
C) Nonkinetochore spindle fibers serve to push
chromosomes in the direction of the poles.
D) The chromosomes are "reeled in" by the
contraction of spindle microtubules, and motor proteins of the kinetochores
move the chromosomes along the spindle microtubules.
E) The chromosomes are "reeled in" by the
contraction of spindle microtubules, motor proteins of the kinetochores move
the chromosomes along the spindle microtubules, and nonkinetochore spindle
fibers serve to push chromosomes in the direction of the poles.
Answer: D
19) Which of the following is a function of those spindle
microtubules that do not attach to kinetochores?
A) maintaining an appropriate spacing among the moving
chromosomes
B) producing a cleavage furrow when telophase is complete
C) providing the ATP needed by the fibers attached to
kinetochores
D) maintaining the region of overlap of microtubules in
the cell's center
E) pulling the poles of the spindles closer to one
another
Answer: D
20) During which phase of mitosis do the chromatids
become chromosomes?
A) telophase
B) anaphase
C) prophase
D) metaphase
E) cytokinesis
Answer: A
21) Which of the following was a discovery that had to be
made before human chromosomes could be correctly counted?
A) how to use a hypotonic solution to swell nuclei
B) how to visualize sperm nuclei
C) how to visualize chromosomes
D) when to see chromosomes separate from one another
E) when to see chromosomes in pairs
Answer: A
22) Which of the following is (are) required for motor
proteins to function in the movement of chromosomes toward the poles of the
mitotic spindle?
A) intact centromeres
B) an MTOC (microtubule organizing center)
C) a kinetochore attached to the metaphase plate
D) ATP as an energy source
E) synthesis of cohesin
Answer: D
23) 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
Answer: C
24) Which of the following proteins are involved in
binary fission as well as eukaryotic mitotic division?
A) cyclins
B) Cdks
C) MPF
D) actin and tubulin
E) cohesins
Answer: D
25) 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
Answer: D
26) 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
Answer: A
27) 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.
Answer: C
28) 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 its complex with a cyclin
E) the binding of PDGF to receptors on the cell surface
Answer: D
29) 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
Answer: A
30) 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
Answer: D
31) 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
Answer: E
32) 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
Answer: B
33) The cyclin component of MPF is destroyed toward the
end of which phase?
A) G₀
B) G₁
C) S
D) G₂
E) M
Answer: E
34) 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) proton pumps.
E) cyclins.
Answer: E
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.
Answer: A
36) 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.
Answer: E
37) 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.
Answer: B
38) 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.
Answer: E
39) Which of the following describe(s) 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.
Answer: E
40) A particular cyclin called cyclin E forms a complex
with Cdk 2 (cyclin-dependent kinase 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 free cyclin E is greatest during the S
phase.
B) The amount of free Cdk 2 is greater during G₁ compared
to the S phase.
C) The amount of free cyclin E is highest during G₁.
D) The amount of free Cdk 2 is greatest during G₁.
E) The activity of the cyclin E/Cdk 2 complex is highest
during G₂.
Answer: C
41) Cells from an advanced malignant tumor most often
have very abnormal chromosomes, and often an abnormal total number of
chromosomes. Why might this occur?
A) Cancer cells are no longer density dependent.
B) Cancer cells are no longer anchorage dependent.
C) Chromosomally abnormal cells can still go through cell
cycle checkpoints.
D) Chromosomally abnormal cells still have normal
metabolism.
E) Transformation introduces new chromosomes into cells.
Answer: C
42) Besides the ability of some cancer cells to
overproliferate, what else could logically result in a tumor?
A) metastasis
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
Answer: C
43) After which checkpoint is the cell first committed to
continue the cell cycle through M?
A) G₀
B) G₁
C) G₂
D) S
E) previous M
Answer: B
44) 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.
Answer: C
45) 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.
Answer: D
46) 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.
Answer: E
47) 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.
Answer: A
48) What explains anchorage dependence of animal cells in
vitro or in vivo?
A) attachment of spindle fibers to centrioles
B) response of the plasma membrane to cell cycle controls
C) the makeup of the extracellular matrix of the
substrate
D) the binding of cell-surface phospholipids to those of
adjoining cells
E) the binding of cell-surface phospholipids to the
substrate
Answer: B
49) A research team 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) They have altered series of cell cycle phases.
D) The cells show characteristics of tumors.
E) They were originally derived from an elderly organism.
Answer: D
50) 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.
Answer: E
51) 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.
Answer: C
52. The lettered circle in Figure 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
52. The lettered circle in Figure 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.
53) What is the correct chromosomal condition for one
daughter nucleus at telophase of mitosis?
A) A
B) B
C) C
D) D
E) E
Answer: E
54) If the cell whose nuclear material is shown in Figure 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
55) In the figure above, mitosis is represented by which
numbered part(s) of the cycle?
A) I
B) II
C) III
D) IV
E) V
Answer: D
56) 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
57) Which number represents DNA synthesis?
A) I
B) II
C) III
D) IV
E) V
Answer: B
58) 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
59) 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
60) MPF reaches its threshold concentration at the end of
this stage.
A) I
B) II
C) III
D) IV
E) V
Answer: C
61. Use the data in Table to answer the following
question.
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
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.
Answer: A
62. Use the data in Table to answer the following
question.
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
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.
Answer: D
Several organisms, primarily protists, have what are
called intermediate mitotic organization.
63) 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
64. 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
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.
65) 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
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.
66) 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
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.
67) 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
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.
68) 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
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.
69) 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
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.
70) 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
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.
71) 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
72) 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
73) 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
74) 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
75) 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
76) 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
77) 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
78) 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
79) 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
Anxwer : E
