Use the following information to answer the questions below.
The unlettered circle at the top of the figure 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 to
E show various combinations of these chromosomes.
Answers:
B C D E
1
Which of the following triggers the cell's passage past the
G2 checkpoint into mitosis?
Answers:
PDGF MPF cyclin Cdk
2
What is the final result of mitosis in a human?
Answers:
genetically identical 2n somatic cells genetically
different 2n somatic cells genetically identical 1n somatic
cells genetically identical 2n gamete cells
1
In eukaryotic cells, chromosomes are composed of _____.
Answers:
DNA and RNA DNA only DNA and proteins
DNA and phospholipids
3
The M-phase checkpoint ensures that all chromosomes are attached to
the mitotic spindle. If this does not happen, cells would most likely
be arrested in _____.
Answers:
telophase prophase prometaphase
metaphase
4
If there are 20 duplicated chromosomes in a cell, how many
centromeres are there?
Answers:
10 20 30 40
2
The microtubule-organizing center found in animal cells is an
identifiable structure present during all phases of the cell cycle.
Specifically, it is known as the _____.
Answers:
microtubulere centrosome centromere
kinetochore
2
Motor proteins require which of the following to function in the
movement of chromosomes toward the poles of the mitotic spindle?
Answers:
intact centromeres a microtubule-organizing
center ATP as an energy source synthesis of
cohesin
3
At which phase are centrioles beginning to move apart in animal cells?
Answers:
anaphase prometaphase metaphase
prophase
4
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 _____.
Answers:
an animal cell in the process of cytokinesis a plant
cell in the process of cytokinesis an animal cell in the S
phase of the cell cycle a plant cell in metaphase
2
How is plant cell cytokinesis different from animal cell cytokinesis
Answers:
The contractile filaments found in plant cells are structures
composed of carbohydrates; the cleavage furrow in animal cells is
composed of contractile phospholipids. Plant cells deposit
vesicles containing cell-wall building blocks on the metaphase
plate; animal cells form a cleavage furrow. The structural
proteins of plant cells separate the two cells; in animal cells, a
cell membrane separates the two daughter cells. Plant cells
divide after metaphase but before anaphase; animal cells divide
after anaphase.
2
Scientists isolate cells in various phases of the cell cycle. They
find a group of cells that have 1 and 1/2 times more DNA than
G1 phase cells. The cells of this group are _____.
Answers:
between the G1 and S phases in the cell cycle
in the G2 phase of the cell cycle in the M
phase of the cell cycle in the S phase of the cell
cycle
4
Metaphase is characterized by _____.
Answers:
aligning of chromosomes on the equator splitting of
the centromeres cytokinesis separation of sister
chromatids
1
The first gap in the cell cycle (G1) corresponds to _____.
Answers:
normal growth and cell function the phase in which
DNA is being replicated the beginning of mitosis
the phase between DNA replication and the M phase
1
Which of the following does NOT occur during mitosis?
Answers:
condensation of the chromosomes replication of the
DNA spindle formation separation of the spindle
poles
2
A cleavage furrow is _____.
Answers:
a ring of vesicles forming a cell plate the
separation of divided prokaryotes a groove in the plasma
membrane between daughter nuclei the space that is created
between two chromatids during anaphase
3
In human and many other eukaryotic species' cells, the nuclear
membrane has to disappear to permit _____.
Answers:
cytokinesis the attachment of microtubules to
kinetochores the splitting of the centrosomes the
disassembly of the nucleolus
2
During which phase of mitosis do the chromatids become chromosomes?
Answers:
telophase anaphase prophase
metaphase
2
If the cell whose nuclear material is shown in the accompanying
figure continues toward completion of mitosis, which of the following
events would occur next?
Answers:
spindle fiber formation nuclear envelope
breakdown formation of telophase nuclei synthesis of
chromatids
3
The beginning of anaphase is indicated by which of the following?
Answers:
Chromatids lose their kinetochores. Cohesin attaches
the sister chromatids to each other. Cohesin is cleaved
enzymatically. Spindle microtubules begin to polymerize.
3