Chapter 12 Biology
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?
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?
100 units
When did the United States declare a "war on cancer" by passing the National Cancer Act?
1971
How many maternal chromosomes are present in a somatic human cell when it is not engaged in cell division?
23
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?
30
Which of the following is closest to the current average annual death rate from cancer in the United States?
580 thousand
If a human somatic cell is just about to divide, it has __________ chromatids.
92
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?
94
Which event or events occur during anaphase?
All of the listed responses are correct. -Cohesins joining sister chromatids at the centromeres are cleaved during anaphase. -A spindle made of microtubules is present during anaphase. -Genetically identical chromosomes (previously sister chromatids) move to opposite poles during anaphase. -The centrioles are at opposite poles during anaphase.
At what point do sister chromatids separate?
Anaphase
Which of the following is false regarding sister chromatids?
Both of the sister chromatids end up in the same daughter cell after cytokinesis has occurred. True: -Sister chromatids are created when DNA is replicated. -Sister chromatids form in the S-phase stage of the cell cycle. -Sister chromatids are attached to one another at the centromere. -Sister chromatids are separated during mitosis.
Which of the following molecules is maintained at a relatively constant level throughout the cell cycle but requires a cyclin to become catalytically active?
Cdk
What is the difference between a benign tumor and a malignant tumor?
Cells of benign tumors do not metastasize; those of malignant tumors do.
In animal cell mitosis, the cleavage furrow forms during which stage of the cell cycle?
Cytokinesis
When a cell in S phase is fused with a cell in G1, __________.
DNA synthesis begins immediately in the original G1 nucleus
Which of the following is involved in the binary fission of most bacteria?
Distribution of a copy of the single parental chromosome to each daughter cell
Which of the following best describes the advantages of the personalized care technique described in the video?
Fruit flies make excellent models because we can create a strain of flies with a specific type of tumor, then raise thousands of flies in order to test the effects of medications.
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
Cells will usually divide if they receive the proper signal at a checkpoint in which phase of the cell cycle?
G1
During what phase in the cell cycle would you find the most DNA per cell?
G2
Which of the following characteristics would be most important for a chemotherapeutic drug designed to treat cancer cells?
It specifically inhibits the cell division cycle in rapidly dividing cells.
At which stage of mitosis are chromosomes lined up in one plane in preparation for their separation to opposite poles of the cell?
Metaphase
Which of the following represents a mismatch or incorrect description?
Metaphase: the nuclear envelope disappears
Which of the following processes does not occur in dividing bacteria?
Mitosis
You would be ,unlikely to see which of the following human cells dividing?
Nerve cell
A cell entering the cell cycle with 32 chromosomes will produce two daughter cells, each with __________.
None of the listed numbers of chromosomes -32 (not 16, not 64, not 32 pairs, not 64 pairs)
In a human skin cell that is going through the cell cycle, when do the centrosomes separate?
Prophase
Which of the following phases of mitosis is essentially the opposite of prometaphase in terms of the nuclear envelope?
Telophase
Which of the following hypotheses is best supported by observing cancer cells in a culture?
The cancer cells do not exhibit density-dependent inhibition.
Which of the following statements best describes what happens to MPF during mitosis?
The cyclin component of MPF is degraded.
The unlettered circle at the top of the accompanying figure shows a diploid nucleus with four chromosomes that have not yet replicated. The circles labeled 1 to 5 show various combinations of these chromosomes. Which chromosomal configuration would be observed in one daughter cell after telophase of mitosis?
V
The region of a chromosome in which the two double strands of replicated DNA are held together is called __________.
a centromere
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 plant cell in the process of cytokinesis.
Which of the following statements describes a characteristic feature of metaphase?
alignment of chromosomes on the equator of the cell
Which of these is NOT a carcinogen?
all of the above are carcinogens: cigarette smoke, fat, UV light, testosterone -carcinogens can cause cancer
The phase of mitosis during which the chromosomes move toward separate poles of the cell is __________.
anaphase
The function of the mitotic cell cycle is to produce daughter cells that __________.
are genetically identical to the parent cell (assuming no mutation has occurred)
Since 1991, deaths from breast and colorectal cancer in the United States are down 35%. What is the main reason for this?
better screening
A biochemist measured the amount of DNA in cells growing in the laboratory and found that the quantity of DNA in the cells doubled __________.
between the G1 and G2 phases
Based on the information in the video, which of the following correctly answers these three questions: What was the leading cause of death in the United States in the early 1970s? What is the leading cause of death in the United States today? What is predicted to be the leading cause of death in the United States 10 years from now?
cancer; cardiovascular disease; cancer
In the cells of some organisms, mitosis occurs without cytokinesis. This will result in
cells with more than one nucleus.
What is the name of the microtubule-organizing center found in animal cells as an identifiable structure present during all phases of the cell cycle?
centrosome
The complex of DNA and protein that makes up a eukaryotic chromosome is properly called
chromatin
The complex of DNA and protein that makes up a eukaryotic chromosome is properly called __________.
chromatin
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
One difference between cancer cells and normal cells is that cancer cells
continue to divide even when they are tightly packed together.
Which of the following molecules is synthesized at specific times during the cell cycle and forms an active complex with a kinase?
cyclin
Which of the following pairs of molecules make up an active MPF?
cyclin and a cyclin-dependent kinase
During interphase, the genetic material of a typical eukaryotic cell is __________.
dispersed in the nucleus as long strands of chromatin
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
disruption of mitotic spindle formation.
Vinblastine is a standard chemotherapeutic drug used to treat cancer. Because it interferes with the assembly of microtubules, its effectiveness must be related to
disruption of mitotic spindle formation.
Which of the following is found in binary fission but not in mitosis?
duplicated chromosomes attach to the plasma membrane
Which of the following events characterizes the beginning of anaphase?
enzymatic cleavage of cohesin
_____ is a carcinogen that promotes colon cancer.
fat
Tissue culture experiments with PDGF demonstrate that without this substance, __________.
fibroblasts fail to divide (PDGF is a growth factor)
Chromatids are __________.
identical copies of each other if they are part of the same duplicated chromosome
Students in a biology lab isolated cells in various phases of the cell cycle. A population of cells that have twice the DNA of G1 phase cells was most likely isolated from which of the following part of the cell cycle?
in the G2 phase
You would know that a dividing cell was a plant cell rather than an animal cell if you saw that __________.
it had formed a cell plate
Which of the following organisms would be most similar to humans in a study that involved the response of cancer cells to various medications?
primates
In telophase of mitosis, the mitotic spindle breaks down and the chromatin uncoils. This is essentially the opposite of what happens in __________.
prophase
Which of the following does not occur during mitosis?
replication of chromosomes
The centromere is a region in which __________.
sister chromatids are attached to one another in prophase
DNA replication occurs in __________.
the S phase of interphase
One event occurring during prophase is __________.
the beginning of the formation of a spindle apparatus
The decline of MPF activity at the end of mitosis is due to
the degradation of cyclin.
"Cytokinesis" refers to __________.
the division of the cytoplasm
Why is the "personalized care" plan described in the video, in which treatments are tailored for each individual, much more promising than previous treatment plans?
the genetic mutations that cause cancer vary from patient to patient
During binary fission in a bacterium, __________.
the origins of replication move apart
Which of the following is true of benign tumors, but not malignant tumors?
they remain confined to their original site
Following cytokinesis in an animal cell, how many centrioles does each new daughter cell possess?
two
