Chapter 12 Practice test
During what phase in the cell cycle would you find the most DNA per cell? ( Concept 12.2) prophase II G2 G1 S S1
G2 Chromosomes are duplicated only during the S phase ("S" stands for synthesis of DNA). The phase following completion of the S phase is G2.
In a human skin cell that is going through the cell cycle, when do the centrosomes separate? (Concept 12.2) metaphase G2 phase S phase prophase anaphase
prophase The centrosomes move away from each other during prophase, apparently propelled along the surface of the nucleus by the lengthening bundles of microtubules between them.
Assume that you are dealing with a species in which the number of chromosomes in each somatic cell is 14. How many sister chromatids are present in the early telophase of mitosis? ( Concept 12.2) 14 0 28 7 None of the listed responses is correct.
0
A cell biologist carefully measured the quantity of DNA in grasshopper cells growing in cell culture. Cells examined during the G2 phase of the cell cycle contained 200 units of DNA. What would be the amount of DNA at G1 of the cell cycle in one of the grasshopper daughter cells? ( Concept 12.2) 100 units 50 units 400 units 200 units between 50 and 100 units
100 units Recall that G2 follows S and that during the S phase, DNA is replicated.
How many maternal chromosomes are present in a somatic human cell not engaged in cell division? (Concept 12.1) 184 92 46 23 None of the listed responses is correct.
23 Each human somatic cell has a total of 46 chromosomes. Only half are maternal chromosomes.
In telophase of mitosis, the mitotic spindle breaks down and the chromatin uncoils. This is essentially the opposite of what happens in _____. ( Concept 12.2) prophase S phase interphase anaphase metaphase
prophase During prophase, we observe the formation of the spindle, the condensation of chromatin, and the disappearance of the nucleolus.
Following cytokinesis in an animal cell, how many centrioles does each new daughter cell possess? (Concept 12.2) four one two zero eight
two Each daughter cell inherits a single centrosome following cytokinesis and each centrosome contains two centrioles.
If a cell contains 60 chromatids at the start of mitosis, how many chromosomes will be found in each daughter cell at the completion of the cell cycle? ( Concept 12.2) 45 15 30 60 120
30 In this case, mitosis starts with 30 chromosomes, each of which consists of two chromatids. At the completion of mitosis, each daughter cell will contain 30 chromosomes.
If a somatic human cell is just about to divide, it has _____ chromatids. ( Concept 12.2) 23 46 92 There is insufficient information to answer the question. 0
92 Human somatic cells have 92 chromatids just prior to cell division due to the replication of the 46 chromosomes that occurred during the S phase.
Down syndrome is characterized by cells having three copies of chromosome 21. As a cell in an individual with Down syndrome prepares to enter mitosis, how many chromatids would be present? (Concept 12.2) 94 46 98 92 23
94 Cells from an individual with Down syndrome would have 23 pairs of chromosomes, plus an extra chromosome for a total of 47. At S phase those chromosomes replicate to produce 94 sister chromatids.
Which event or events occur during anaphase? ( Concept 12.2) identical chromatids move to opposite poles the centromeres divide the centrioles are at opposite poles a spindle made of microtubules is present All of the listed responses are correct.
All are correct. Correct. Anaphase begins when the paired centromeres of each chromosome separate, liberating the sister chromatids, which begin moving toward opposite poles of the cell.
Which of the following is false regarding sister chromatids? ( Concept 12.1) Sister chromatids are created when DNA is replicated. Sister chromatids are attached to one another at the centromere. Both of the sister chromatids end up in the same daughter cell after cytokinesis has occurred. Sister chromatids form in the S-phase stage of the cell cycle. Sister chromatids are separated during mitosis.
Both of the sister chromatids end up in the same daughter cell after cytokinesis has occurred. This statement is false. Each of the sisters ends up in a different cell after cell division.
What is the difference between a benign tumor and a malignant tumor? ( Concept 12.3) Benign tumors will not kill you; malignant tumors will. Benign tumors do not arise by transformation; malignant tumors do. Benign tumors arise by transformation; malignant tumors do not. Cells of benign tumors do not metastasize; those of malignant tumors do. Cells of benign tumors metastasize; those of malignant tumors do not.
Cells of benign tumors do not metastasize; those of malignant tumors do. Cells of malignant tumors spread from their site of origin to other parts of the body.
When a cell in S phase is fused with a cell in G1, _____. ( Concept 12.3) the replication of DNA occurring in the original S nucleus is terminated the chromosomes of the original G1 nucleus condense in preparation for mitosis the two nuclei fuse and further division is arrested DNA synthesis begins immediately in the original G1 nucleus the original G1 cell will divide immediately
DNA synthesis begins immediately in the original G1 nucleus DNA synthesis begins immediately in the original G1 nucleus
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 G1. prophase. G2. anaphase. metaphase.
G1
A cell entering the cell cycle with 32 chromosomes will produce two daughter cells, each with _____. (Concept 12.1) 64 pairs of chromosomes 64 chromosomes 32 pairs of chromosomes 16 chromosomes None of the listed responses is correct.
None of the listed responses is correct. There would be 32 chromosomes present in each of the daughter cells.
The person credited with first recognizing (in the 1860s) that living cells cannot arise spontaneously, but arise only from previously existing cells, is _____. ( Overview) Louis Pasteur Anton van Leeuwenhoek Robert Hooke Rudolf Virchow Watson
Rudolf Virchow Correct. In 1855 Rudolf Virchow stated, "Where a cell exists, there must have been a preexisting cell."
The region of a chromosome holding the two double strands of replicated DNA together is called _____. ( Concept 12.1) a centromere a centriole a chromatid an aster chromatin
a centromere The chromosome has a narrow "waist" at a specialized region, called the centromere, where the two chromatids are attached to each other.
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 an animal cell in the process of cytokinesis. an animal cell in the S phase of the cell cycle. a plant cell in metaphase. a plant cell in the process of cytokinesis. a bacterial cell dividing.
a plant cell in the process of cytokinesis.
During which stage of the cell cycle do sister chromatids separate? ( Concept 12.2) anaphase prophase G2 phase metaphase G1 phase
anaphase Anaphase begins when the paired centromeres of each chromosome separate, liberating the sister chromatids, which begin moving toward opposite poles of the cell.
The phase of mitosis during which the chromosomes move toward separate poles of the cell is _____. ( Concept 12.2) prophase metaphase telophase prometaphase anaphase
anaphase Anaphase begins when the paired centromeres of each chromosome separate, liberating the sister chromatids, which begin moving toward opposite poles of the cell.
The function of the mitotic cell cycle is to produce daughter cells that _____. ( Concept 12.1) have the same number of chromatids as the parent cell had chromosomes are genetically identical to the parent cell (assuming no mutation has occurred) have the same number of chromosomes as the parent cell but not the same genetic content have a random assortment of maternal and paternal chromosomes None of the listed responses is correct.
are genetically identical to the parent cell (assuming no mutation has occurred) Cell division involves the distribution of identical genetic material (DNA) to two daughter chromosomes.
A biochemist measured the amount of DNA in cells growing in the laboratory and found that the quantity of DNA in the cells doubled _____. ( Concept 12.2) between prophase and anaphase between the G1 and G2 phases between the G2 phase and prophase between anaphase and telophase during the M phase of the cell cycle
between the G1 and G2 phases Between these two phases of the cell cycle, the DNA is replicated during the S phase.
In the cells of some organisms, mitosis occurs without cytoki-nesis. This will result in destruction of chromosomes. cell cycles lacking an S phase. cells that are unusually small. cells with more than one nucleus. cells lacking nuclei.
cells with more than one nucleus.
The complex of DNA and protein that makes up a eukaryotic chromosome is properly called _____. (Concept 12.1) chromatin a centromere a chromoplast a chromatid a centrosome
chromatin Correct. The DNA-protein complex called chromatin is organized into a long, thin fiber.
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? cleavage furrow formation and cytokinesis DNA synthesis spindle formation spindle attachment to kinetochores cell elongation during anaphase
cleavage furrow formation and cytokinesis
One difference between cancer cells and normal cells is that cancer cells are unable to synthesize DNA. are always in the M phase of the cell cycle. are arrested at the S phase of the cell cycle. continue to divide even when they are tightly packed together. cannot function properly because they are affected by density-dependent inhibition.
continue to divide even when they are tightly packed together.
In animal cell mitosis, the cleavage furrow forms during which stage of the cell cycle? ( Concept 12.2) cytokinesis the G1 phase metaphase anaphase prophase
cytokinesis Cytokinesis is usually well under way by telophase. In animal cells, cytokinesis involves the formation of a cleavage furrow, which pinches the cell in two.
During interphase, the genetic material of a typical eukaryotic cell is _____. ( Concept 12.2) transported through the nuclear pores attached to microtubule spindle fibers dispersed in the cytoplasm as long strands of chromatin dispersed in the nucleus as long strands of chromatin condensed and the chromosomes are often visible under the light microscope
dispersed in the nucleus as long strands of chromatin During interphase, the chromosomes cannot be distinguished individually because they are still in the form of loosely packed chromatin fibers.
Vinblastine is a standard chemotherapeutic drug used to treat cancer. Because it interferes with the assembly of micro-tubules, its effectiveness must be related to suppression of cyclin production. disruption of mitotic spindle formation. inhibition of DNA synthesis. inhibition of regulatory protein phosphorylation. myosin denaturation and inhibition of cleavage furrow formation.
disruption of mitotic spindle formation.
Which of the following is involved in the binary fission of bacteria? ( Concept 12.2) formation of a cell plate formation of a spindle apparatus distribution of a copy of the single parental chromosome to each daughter cell disintegration of the nuclear membrane prophase, prometaphase, metaphase, anaphase, and telophase
distribution of a copy of the single parental chromosome to each daughter cell distribution of a copy of the single parental chromosome to each daughter cell
"Cytokinesis" refers to _____. ( Concept 12.1) movement of a cell from one place to another reduction in the number of chromosomes division of the cytoplasm division of the entire cell division of the nucleus
division of the cytoplasm Cytokinesis is the division of the cytoplasm that follows the mitotic division of the nucleus.
Observations of cancer cells in culture support the hypothesis that cancer cells _____. ( Concept 12.3) spend the majority of their time in the G0 phase exhibit anchorage dependence produce molecules that inhibit the growth factors required for cell division do not exhibit density-dependent inhibition All of the listed responses are correct.
do not exhibit density-dependent inhibition Correct. Normal cells respond to density-dependent inhibition by growing in culture to form a single layer of cells.
Tissue culture experiments with PDGF demonstrate that without this substance _____. ( Concept 12.3) animal cells are unable to attach to the substratum cells divide in an uncontrolled fashion, confirming PDGF's role as a cell division inhibitor the various kinases, such as MPF, are unable to bind to cyclin fibroblasts fail to divide bacterial cells lose their resistance to antibiotics
fibroblasts fail to divide PDGF is a specific growth factor for fibroblasts.
Chromatids are _____. ( Concept 12.1) identical copies of each other if they are part of the same chromosome composed of RNA found only in aberrant chromosomes held together by the centrioles the bacterial equivalent of eukaryotic chromosomes
identical copies of each other if they are part of the same chromosome Each duplicated chromosome consists of two identical sister chromatids.
You would know a dividing cell was a plant cell rather than an animal cell if you saw that _____. (Concept 12.2) it had two pairs of centrioles during prophase it had microtubules it had formed a cell plate it had formed a cleavage furrow the nucleolus was visible during metaphase
it had formed a cell plate The cell plate, which divides the cytoplasm in two, forms during the telophase of mitosis in a plant cell.
At which stage of mitosis are chromosomes lined up in one plane in preparation for their separation to opposite poles of the cell? ( Concept 12.2) interphase telophase prophase anaphase metaphase
metaphase The chromosomes convene on the metaphase plate, an imaginary plane that is equidistant from the spindle's two poles.
Which of the following represents a mismatch or incorrect description? ( Concept 12.2) metaphase: the nuclear envelope disappears prophase: chromosomes become more tightly coiled anaphase: there is movement of the chromosomes to the poles telophase: chromosomes become more extended metaphase: chromosomes line up on the equatorial plane
metaphase: the nuclear envelope disappears During prometaphase, the nuclear envelope fragments.
Which of the following processes does NOT occur in dividing bacteria? ( Concept 12.2) mitosis binary fission separation of the origins of replication replication of DNA inward growth of the plasma membrane
mitosis Mitosis does not occur in dividing bacteria. Mitosis might have had its origins in simpler bacterial mechanisms of cell reproduction. Prokaryotes (bacteria) reproduce by a type of cell division called binary fission.
You would be unlikely to see which of the following human cells dividing? ( Concept 12.3) skin cell cancer cell cell from an embryo nerve cell intestinal lining cell
nerve cell Nerve cells are quite complex and specialized. After reaching maturity, they enter the G0 phase.
Which of the following does NOT occur during mitosis? ( Concept 12.2) replication of chromosomes condensation of chromatin alignment of chromosomes along the cell's equator separation of chromatids the movement of chromosomes to opposite poles
replication of chromosomes The DNA of the chromosomes is replicated in the S phase before mitosis.
Which of the following does not occur during mitosis? replication of the DNA spindle formation separation of the spindle poles condensation of the chromosomes separation of sister chromatids
replication of the DNA
The centromere is a region in which _____. ( Concept 12.1) the new cell plate forms in telophase microtubules are fastened to the centrioles during anaphase chromosomes become aligned during metaphase sister chromatids are attached to one another in prophase the chromosomes are connected to the cell plate in metaphase
sister chromatids are attached to one another in prophase The chromosome has a narrow "waist" at a specialized region called the centromere, where sister chromatids are attached.
Which of the following phases of mitosis is essentially the opposite of prometaphase in terms of the nuclear envelope? ( Concept 12.2) S phase interphase anaphase telophase metaphase
telophase Correct. In prometaphase the nuclear envelope fragments and the kinetochores attach to microtubules. During telophase, fragments of the nuclear envelope begin to reassemble along with portions of the endomembrane system.
DNA replication occurs in _____. ( Concept 12.2) prophase of both mitosis and meiosis the cytokinesis portion of the cell's life cycle metaphase of meiosis only the S phase of interphase in both somatic and reproductive cells the G1 phase of interphase in reproductive cells only
the S phase of interphase in both somatic and reproductive cells Chromosomes are duplicated only during the S phase ("S" stands for synthesis of DNA).
One event occurring during prophase is _____. ( Concept 12.2) the alignment of chromosomes in a single plane division of the centromere the synthesis of a new nuclear envelope the beginning of the formation of a spindle apparatus cytokinesis
the beginning of the formation of a spindle apparatus During prophase, the mitotic spindle begins to form.
The decline of MPF activity at the end of mitosis is due to the accumulation of cyclin. the degradation of cyclin. decreased synthesis of Cdk. synthesis of DNA. the destruction of the protein kinase Cdk.
the degradation of cyclin.
During binary fission in a bacterium _____. ( Concept 12.2) the two DNA molecules attach to the centrioles the origins of replication move apart the two DNA molecules break up into plasmids the two DNA molecules float free in the cell and are guided to daughter cells by a spindle-like apparatus the two DNA molecules divide in half, forming four DNA fragments
the origins of replication move apart the origins of replication move apart
