Font size
WorksheetsAP Biology Unit 4: Cell Communication & Cell Cycle
Total questions: 85
Worksheet time: 43mins
What could happen to the target cells in an animal that lack receptors for local regulators?
They could compensate by receiving nutrients via an a factor.
They could develop normally in response to neurotransmitters instead.
They could divide but never reach full size.
They would not be able to multiply in response to growth factors from nearby cells
From the perspective of the cell receiving the message, the three stages of cell signaling are
signal reception, signal transduction, and cellular response.
signal reception, nucleus disintegration, and new cell generation
the alpha, beta, and gamma stages.
signal reception, cellular response, and cell division.
The process of transduction usually begins
when the chemical signal is released from the alpha cell.
when the signal molecule changes the receptor protein in some way.
after the target cell divides.
after the third stage of cell signaling is completed.
Paracrine signaling
involves secreting cells acting on nearby target cells by discharging a local regulator into the extracellular fluid.
requires nerve cells to release a neurotransmitter into the synapse.
occurs only in paracrine yeast cells.
When a cell releases a signal molecule into the environment and a number of cells in the immediate vicinity respond, this type of signaling is
autocrine signaling.
paracrine signaling.
endocrine signaling
synaptic signaling.
Synaptic signaling between adjacent neurons is like hormone signaling in which of the following ways?
It sends its signal molecules through the blood.
It sends its signal molecules quite a distance.
It requires binding of a signaling molecule to a receptor.
It persists over a long period.
A small molecule that specifically binds to another molecule, usually a larger one
is called a signal transducer.
is called a ligand.
is called a polymer.
[Select all that apply] Which of the following is (are) true of ligand-gated ion channels?
They are important in the nervous system.
They lead to changes in sodium and calcium concentrations in cells.
They open or close in response to a chemical signal.
Of the following, a receptor protein in a membrane that recognizes a chemical signal is most similar to
the active site of an allosteric enzyme in the cytoplasm that binds to a specific substrate.
RNA specifying the amino acids in a polypeptide.
a particular metabolic pathway operating within a specific organelle.
genes making up a chromosome.
What would be true for the signaling system in an animal cell that lacks the ability to produce GTP?
It would not be able to activate and inactivate the G protein on the cytoplasmic side of the plasma membrane.
It could activate only the epinephrine system.
It would be able to carry out reception and transduction, but would not be able to respond to a signal.
G proteins and G-protein-linked receptors
are found only in animal cells, and only embedded in or located just beneath the cellʹs membrane.
are found only in bacterial cells, embedded in the cellʹs plasma membrane only.
are thought to have evolved very early, because of their similar structure and function in a wide variety of modern organisms.
Membrane receptors that attach phosphates to specific animo acids in proteins are
not found in humans.
called receptor tyrosine-kinases.
a class of GTP G-protein signal receptors.
Up to 60% of all medicines used today exert their effects by influencing what structures in the cell membrane?
tyrosine-kinases receptors
ligand-gated ion channel receptors
growth factors
G proteins
Testosterone functions inside a cell by
acting as a signal receptor that activates ion-channel proteins.
binding with a receptor protein that enters the nucleus and activates specific genes.
Which is true of transcription factors?
They regulate the synthesis of DNA in response to a signal.
Some transcribe ATP into cAMP.
They control which genes are expressed.
Chemical signal pathways
operate in animals, but not in plants.
are absent in bacteria, but are plentiful in yeast.
involve the release of hormones into the blood.
often involve the binding of signal molecules to a protein on the surface of a target cell.
In general, a signal transmitted via phosphorylation of a series of proteins
brings a conformational change to each protein.
requires binding of a hormone to a cytosol receptor.
cannot occur in yeasts because they lack protein phosphatases.
requires phosphorylase activity.
The general name for an enzyme that transfers phosphate groups from ATP to a protein is
phosphorylase.
phosphatase.
protein kinase
Which of the following describes cell communication systems?
Communicating cells are usually close together.
In response to a signal, the cell may alter activities by changes in cytosol activity or in transcription of RNA.
Which of the following would be inhibited by a drug that specifically blocks the addition of phosphate groups to proteins?
G-protein-linked receptor signaling
receptor tyrosine kinase activity
Caffeine is an inhibitor of phosphodiesterase. Therefore, the cells of a person who has recently consumed coffee would have increased levels of
phosphorylated proteins
GTP
cAMP
adenylyl cyclase
Which of the following is a correct association?
kinase activity and the addition of a tyrosine
GTPase activity and hydrolysis of GTP to GDP
adenylyl cyclase activity and the conversion of cAMP to AMP
At puberty, an adolescent female body changes in both structure and function of several organ systems, primarily under the influence of changing concentrations of estrogens and other steroid hormones. How can one hormone, such as estrogen, mediate so many effects?
Estrogen is produced in very large concentration and therefore diffuses widely.
Estrogen has specific receptors inside several cell types, but each cell responds in the same way to its binding.
Estrogen binds to specific receptors inside many kinds of cells, each of which have different responses to its binding.
The termination phase of cell signaling requires which of the following?
removal of the receptor
activation of a different set of relay molecules
converting ATP to camp
reversing the binding of signal molecule to the receptor
Which of the following describes the events of apoptosis?
The cell dies, it is lysed, its organelles are phagocytized, its contents are recycled.
Its DNA and organelles are fragmented, the cell shrinks and forms blebs, and the cell self-digests.
The centromere is a region in which
chromatids remain attached to one another until anaphase.
metaphase chromosomes become aligned at the metaphase plate.
What is a chromatid?
a chromosome in G1 of the cell cycle
a replicate chromosome
Starting with a fertilized egg (zygote), a series of five cell divisions would produce an early embryo with how many cells?
4
8
16
32
If there are 20 chromatids in a cell, how many centromeres are there?
10
20
30
40
How do the daughter cells at the end of mitosis and cytokinesis compare with their parent cell when it was in G1 of the cell cycle?
The daughter cells have half the amount of cytoplasm and half the amount of DNA.
The daughter cells have the same number of chromosomes and the same amount of DNA.
Which term describes centrioles beginning to move apart in animal cells?
telophase
anaphase
metaphase
prophase
Which term describes centromeres uncoupling, sister chromatids separating, and the two new chromosomes moving to opposite poles of the cell?
telophase
anaphase
metaphase
prophase
If cells in the process of dividing are subjected to colchicine, a drug that interferes with the functioning of the spindle apparatus, at which stage will mitosis be arrested?
anaphase
prophase
telophase
metaphase
A cell containing 92 chromatids at metaphase of mitosis would, at its completion, produce two nuclei each containing how many chromosomes?
12
16
23
46
If the cell whose nuclear material is shown in the Figure continues toward completion of mitosis, which of the following events would occur next?
cell membrane synthesis
spindle fiber formation
formation of telophase nuclei
If there are 20 centromeres in a cell at anaphase, how many chromosomes are there in each daughter cell following cytokinesis?
10
20
30
40
If there are 20 chromatids in a cell at metaphase, how many chromosomes are there in each daughter cell following cytokinesis?
10
20
30
40
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
contain no DNA
contain no RNA.
contain only one chromosome that is very short.
are actually in the G0 phase.
Where do the microtubules of the spindle originate during mitosis in both plant and animal cells?
centromere
centrosome
centriole
chromatid
If a cell has 8 chromosomes at metaphase of mitosis, how many chromosomes will it have during anaphase?
1
2
4
16
Cytokinesis usually, but not always, follows mitosis. If a cell completed mitosis but not cytokinesis, the result would be a cell with
a single large nucleus
two nuclei
two nuclei but with half the amount of DNA
Regarding mitosis and cytokinesis, one difference between plants and animals is that in plants
a cell plate begins to form at telophase, whereas in animals a cleavage furrow is initiated at that stage.
chromosomes become attached to the spindle at prophase, whereas in animals chromosomes do not become attached until anaphase.
Chromosomes first become visible during which phase of mitosis?
telophase
prophase
metaphase
anaphase
During which phases of mitosis are chromosomes composed of two chromatids?
from interphase through anaphase
from G1 of interphase through metaphase
from anaphase through telophase
from G2 of interphase through metaphase
Movement of the chromosomes during anaphase would be most affected by a drug that
prevents elongation of microtubules.
prevents shortening of microtubules.
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 was the nucleus with 6 picograms of DNA?
G0
G1
S
G2
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. Those cells would have picograms at the end of the S phase and picograms at the end of G2.
8; 8
8;16
16;16
The somatic cells derived from a single-celled zygote divide by which process?
meiosis
mitosis
binary fission
Imagine looking through a microscope at a squashed onion root tip. The chromosomes of many of the cells are plainly visible. In some cells, replicated chromosomes are aligned along the center (equator) of the cell. These particular cells are in which stage of mitosis?
telophase
prophase
anaphase
metaphase
Why do chromosomes coil during mitosis?
to allow the chromosomes to move without becoming entangled and breaking
to allow the sister chromatids to remain attached
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. Which of the following questions might be answered by such a method?
How many cells are produced by the culture per hour?
What is the length of the S phase of the cell cycle?
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.
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
the presence of the pathogen made the experiment too contaminated to trust the results.
infection causes lymphocytes to divide more rapidly.
infection causes lymphocyte cultures to skip some parts of the cell cycle.
If mammalian cells receive a go-ahead signal at the G1 checkpoint, they will
move directly into telophase.
complete the cycle and divide.
Cells that are in a nondividing state are in which phase?
G0
G2
G1
S
Which is a general term for enzymes that activate or inactivate other proteins by phosphorylating them?
MPF
protein kinase
cyclin
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?
PDGF
MPF
protein kinase
cyclin
Which of the following is a protein maintained at constant levels throughout the cell cycle that requires cyclin to become catalytically active?
MPF
protein kinase
cyclin
cdk
DNA is replicated at this time of the cell cycle
G0
G1
S
G2
Nerve and muscle cells are in this phase:
G0
G1
S
G2
Density-dependent inhibition is explained by which of the following?
As cells become more numerous, they begin to squeeze against each other, restricting their size and ability to produce control factors.
As cells become more numerous, the cell surface proteins of one cell contact the adjoining cells and they stop dividing.
[select all that apply] Which of the following is true concerning cancer cells?
They do not exhibit density-dependent inhibition when growing in culture.
When they stop dividing, they do so at random points in the cell cycle.
They are not subject to cell cycle controls
[select all that apply] Which of the following describe(s) cyclin-dependent kinase (Cdk)?
Cdk is inactive, or ʺturned off,ʺ in the presence of cyclin.
Cdk is present throughout the cell cycle.
Cdk is an enzyme that attaches phosphate groups to other proteins.
A particular cyclin called cyclin E forms a complex with a cyclin-dependent kinase called Cdk 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?
The amount of cyclin E is greatest during the S phase.
The amount of cyclin E is highest during G1.
Cells from an advanced malignant tumor most often have very abnormal chromosomes, and often an abnormal total number of chromosomes. Why might this occur?
Chromosomally abnormal cells can still go through cell cycle checkpoints.
Transformation introduces new chromosomes into cells.
Besides the ability of some cancer cells to overproliferate, what else could logically result in a tumor?
lack of appropriate cell death
inability to form spindles
