biology chapter 9 test
If there are 20 centromeres in a cell at anaphase of mitosis, how many chromosomes are there in each daughter cell following cytokinesis?
10
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?
16;16
When did the United States declare a "war on cancer" by passing the National Cancer Act?
1971
Approximately what proportion of human genes are thought to encode protein kinases?
2%
Beginning with a fertilized egg (zygote), a series of five cell divisions would produce an early embryo with how many cells?
32
Which of the following is closest to the current average annual death rate from cancer in the United States?
580 thousand
A group of cells is assayed for DNA content immediately before beginning mitosis and is found to have an average of 16 picograms of DNA per nucleus. How many picograms would be in a cell nucleus following completion of mitosis and cytokinesis?
8
A human bone marrow cell, in prophase of mitosis, contains 46 chromosomes. How many chromatids does it contain?
92
Select the statement that makes a correct prediction about natural phenomena that could occur during the cell cycle to prevent cell growth.
As cells become more numerous, the amount of required growth factors and nutrients per cell becomes insufficient to allow for cell growth.
Density-dependent inhibition is explained by which of the following?
As cells become more numerous, the cell surface proteins of adjacent cells bind to each other and send signals that inhibit cell division.
What is the correct chromosomal condition for a nucleus at prophase of mitosis?
B (different lengths of double things with different color)
Cells from advanced malignant tumors frequently have very abnormal chromosomes as well as an abnormal number of chromosomes. What might explain the association between malignant tumors and chromosomal abnormalities?
Cell cycle checkpoints are not in place to stop cells with chromosome abnormalities.
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 animal cells in G2?
Chromosome condensation would occur, but the chromosomes would fail to align at the metaphase plate.
Select the part of the cell cycle where the cell actually produces two new identical cells.
Cytokinesis when the cytoplasm divides forming two new cells.
Eukaryotic chromatin is composed of
DNA and proteins.
Which statement provides the best description of the interphase portion of the cell cycle?
During interphase, a cell is metabolically active.
What is the correct chromosomal condition for a nucleus in G1 of the cell division cycle?
E (different lengths of singular things with different color)
Which image displays the chromosomal composition of one daughter nucleus at telophase of mitosis?
E (different lengths of singular things with different color)
If a eukaryotic cell is in the G1 phase of the cell cycle, which statement about the cell's chromosomes must be correct?
Each chromosome is made of a complex of DNA and associated proteins.
How can one hormone, such as estrogen, mediate so many effects?
Estrogen binds to specific receptors inside many kinds of cells, each of which has different responses to its binding.
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.
Following activation of a receptor, which sequence below represents the correct order in which components will be involved in a signaling pathway that utilizes the second messenger cAMP?
G protein → adenyl cyclase → cAMP → protein kinase
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
Which is the first checkpoint in the cell cycle where a cell will be caused to exit the cycle if this point is not passed?
G1
Which of the following correctly matches a phase of the cell cycle with its description?
G1: follows cell division
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 would the nucleus contain 6 picograms of DNA?
G2
Which of the following is the most plausible explanation for the difference in time spent in S phase by beta and gamma?
Gamma contains more DNA than beta.
The cell cycle control systems of cancer cells differ from those of normal cells. Select the best explanation for this fact.
Genetic changes alter the function of the cancer cell's protein products.
Which of the following is the greatest advantage of having multiple steps in a transduction pathway?
Having multiple steps provides for greater possible amplification of a signal.
G1 is represented by which numbered part(s) of the cycle?
I or V (low flat parts)
In the figure, G1 is represented by which numbered parts of the cycle?
I or V (low flat parts)
In the figure, DNA synthesis is represented by which numbered parts of the cycle?
II (increasing slope)
In the figure, which number represents the point in the cell cycle during which the chromosomes are replicated?
II (increasing slope)
In the figure, G2 is represented by which numbered parts of the cycle?
III only (top flat part)
In the figure, which of the numbered regions would contain cells at metaphase?
III only (top flat part)
For a chemotherapeutic drug to be useful for treating cancer cells, which of the following is most desirable?
It targets only rapidly dividing cells.
If an animal cell suddenly lost the ability to produce GTP, what might happen to its signaling system?
It would not be able to activate G proteins on the cytoplasmic side of the plasma membrane.
Which of the following is released by platelets in the vicinity of an injury?
PDGF
Which of the following characteristics is unique to plant hormones?
Plant hormones may be delivered to target cells through the air.
You have a series of cells, all of which were derived from tumors. How might you determine which ones are malignant?
Prepare karyotypes to identify the ones with aberrant chromosome number or structure.
Researchers 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?
The cells show characteristics of tumors.
Which of the following is the first event that occurs following the binding of a ligand by a membrane receptor protein?
The membrane receptor protein undergoes a conformational change.
Diatoms and some yeasts are unicellular eukaryotes that have mechanisms of nuclear division that may resemble intermediate steps in the evolution of mitosis. Which of the following is a characteristic feature of nuclear division in these organisms?
The nuclear envelope remains intact during division.
Which of the following is true of steroid receptors?
The receptor molecules may be soluble proteins in the cytoplasm.
Which of the following is true of kinetochores?
They are sites at which microtubules attach to chromosomes.
Which of the following is true concerning cancer cells?
They evade the normal controls that trigger programmed cell death.
Why do neurons and some other specialized cells divide infrequently?
They have been shunted into G0.
What is true of all cancers?
They have escaped normal cell cycle controls.
Why is it difficult to observe individual chromosomes with a light microscope during interphase?
They have uncoiled to form long, thin strands.
Why do some species employ both mitosis and meiosis, whereas other species use only mitosis?
They need both if they are reproducing sexually.
Which of the following is true of benign tumors but not malignant tumors?
They remain confined to their original site.
Several organisms, including a number of protists, have intermediate mitotic organization. Which of the following is the most probable hypothesis regarding these intermediate forms of cell division?
They show some but not all of the evolutionary steps toward complete mitosis.
Which of the following is the most likely fate of animal cells that lack receptors for local paracrine signal molecules?
They would be unable to grow and divide in response to growth factors from nearby cells.
Which of the following question might be answered by such a method?
What is the length of the S phase of the cell cycle?
When a cell is in late anaphase of mitosis, which of the following may be seen?
a clear area in the center of the dividing cell
A drug designed to inhibit the response of cells to testosterone would almost certainly result in which of the following?
a decrease in transcriptional activity of certain genes
What is a cleavage furrow?
a groove in the plasma membrane between daughter nuclei
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
The primary function of kinases in signal transduction is to
activate protein kinases or other relay molecules in a series.
Immediately following binding of a growth factor, an activated receptor would most likely stimulate
activation of a protein kinase.
Which of these is NOT a carcinogen?
all of the above are carcinogens
In which of the following ways could signal transduction most probably be explored in research to treat cancer?
alteration of protein kinases in cell cycle regulation in order to slow cancer growth
At which phase of mitosis do the sister chromatids become daughter chromosomes?
anaphase
Centromeres divide and sister chromatids become full-fledged chromosomes during _____.
anaphase
(chart showing Minutes Spent in Cell Cycle Phases) The best conclusion concerning delta is that the cells
are actually in the G0 phase.
The loop on the cytosol side between helices 5 and 6 is usually substantially longer than the others.The coupled G protein most likely interacts with this receptor
at the loop between helices 5 and 6.
Since 1991, deaths from breast and colorectal cancer in the United States are down 35%. What is the main reason for this?
better screening
The mechanism by which testosterone alters cell function is by
binding to a receptor protein that enters the nucleus and activates specific genes.
How do cancer cells differ from normal cells?
cancer cells may be immortal
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
Most animal cells exhibit anchorage dependence, which means that in order to divide
cells must be attached to a substrate or extracellular matrix of a tissue.
In the cells of some organisms, mitosis occurs WITHOUT cytokinesis. This will result in __________.
cells with more than one nucleus
Where do the microtubules of the spindle originate during mitosis in animal cells?
centrosome
Cytochalasin B is a chemical that disrupts microfilament formation. How would this interfere with cell division?
cleavage
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
The protein complex that activates progress through the M phase checkpoint will allow which of the following to occur?
cleavage of cohesin proteins by separase
The cell cycle is regulated at the molecular level by a set of proteins known as
cyclins
Which of the following would provide evidence that this is related to cell signaling?
decreased affinity of growth factor receptors for their respective ligands
The beginning of anaphase is indicated by which of the following?
enzymatic cleavage of cohesin
_____ is a carcinogen that promotes colon cancer.
fat
Which of the following are primarily responsible for cytokinesis in plant cells but not in animal cells?
golgi-derived vesicles
The primary function of phosphatases in signal transduction is to
inactivate protein kinases to turn off signal transduction.
Sutherland discovered that the signaling molecule epinephrine
increases concentrations of cyclic AMP in the cytoplasm.
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
infection causes lymphocytes to divide more rapidly.
During _____ the cell grows and replicates both its organelles and its chromosomes.
interphase
Nucleoli are present during _____.
interphase
Which of the following enzymes adds a phosphate group to target proteins?
kinase
Besides the ability of some cancer cells to divide uncontrollably, what else could logically result in a tumor?
lack of appropriate cell death
In some organisms, such as certain fungi and algae, cells undergo the cell cycle repeatedly without subsequently undergoing cytokinesis. What would result from this?
large cells containing many nuclei
A signal molecule is also known as a(n) _____.
ligand
Taxol is an anticancer drug extracted from the Pacific yew tree that binds to microtubules and prevents their depolymerization. Actively dividing cells treated with Taxol become blocked in which phase of mitosis?
metaphase
Which of these is a receptor molecule?
molecule inside of cell
Compared to most prokaryotic cells, eukaryotic cells typically have
more DNA molecules and larger genomes.
In the figure, the dots in the space between the two structures represent which of the following?
neurotransmitters
Where are the motor proteins that move chromosomes toward the poles of the mitotic spindle located?
on the kinetochores
What is produced if a cell completes mitosis but does not undergo cytokinesis?
one cell with two nuclei, each identical to the nucleus of the parent cell
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?
organelle density and enzymatic activity
The secretion of a signal molecule by a cell into the local environment, followed by a response by a number of cells in the immediate vicinity, is an example of
paracrine signaling
Which of the following correctly describes the relationship between an enzyme and its function?
phosphatase: removal of a phosphate group
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
Spindle fibers attach to kinetochores during _____.
prometaphase
Chromosomes become visible during _____.
prophase
During mitosis in animal cells, at which phase do centrioles begin to move apart?
prophase
Which of the following does NOT occur during mitosis?
replication of DNA
In general, a signal transmitted via a phosphorylation cascade
results in a conformational change in each phosphorylated protein.
If the cell whose nuclear material is shown in the figure continues toward completion of mitosis, which of the following events would occur next?
segregation of daughter chromosomes toward the poles
Movement of the chromosomes during anaphase would be most affected by a drug that prevents
shortening of microtubules.
A signal transduction pathway is initiated when a _____ binds to a receptor.
signal molecule
When a neuron responds to a particular neurotransmitter by opening gated ion channels, the neurotransmitter is serving as which part of the signal pathway?
signal molecule
Which of these is a signal molecule?
smaller molecule outside of cell
Which of the following types of signaling is represented between the nerve cells in the figure?
synaptic
Cytokinesis often, but not always, accompanies _____.
telophase
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 _____ both the contents of the nucleus and the cytoplasm are divided.
the mitotic phase
The primary function of transcription factors is
to regulate gene expression.
The primary function of G proteins in signal transduction is
transducing the signal from an activated receptor to the next protein in the pathway.
Which of these is the second of the three stages of cell signaling?
transduction
Humans produce skin cells by mitosis and gametes by meiosis. The nuclei of skin cells produced by mitosis will have
twice as much DNA as the nuclei of gametes produced by meiosis.