Mastering Bio Ch. 12

Front 1

If there are 20 centromeres in a cell at anaphase, how many chromosomes are there in each daughter cell following cytokinesis?

80
20
30
10
40

Back 1

10

Front 2

Where do the microtubules of the spindle originate during mitosis in animal cells?

centriole
centrosome
chromatid
centromere
kinetochore

Back 2

centrosome

Front 3

Taxol is an anticancer drug extracted from the Pacific yew tree. In animal cells, Taxol disrupts microtubule formation by binding to microtubules and accelerating their assembly from the protein precursor, tubulin. Surprisingly, this stops mitosis. Specifically, Taxol must affect

the S phase of the cell cycle.
anaphase.
formation of the centrioles.
the formation of the mitotic spindle.
chromatid assembly.

Back 3

Formation of the mitotic spindle

Front 4

Which of the following are primarily responsible for cytokinesis in plant cells but not in animal cells?

actin and myosin
centrioles and centromeres
tubulin and dynein
Golgi-derived vesicles
kinetochores

Back 4

Golgi-derived vesicles

Front 5

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 did the nucleus contain 6 picograms of DNA?

G0
G2
S
M
G1

Back 5

G2

Front 6

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?

12; 16
8; 16
8; 8
16; 16
16; 8

Back 6

16;16

Front 7

The beginning of anaphase is indicated by which of the following?

Kinetochores attach to the metaphase plate.
Spindle microtubules begin to polymerize.
Cohesin attaches the sister chromatids to each other.
Cohesin is cleaved enzymatically.
Chromatids lose their kinetochores.

Back 7

Cohesin is cleaved enzymatically

Front 8

Using which of the following techniques would enable your lab group to distinguish between a cell in G2 and a cell from the same organism in G1?

fluorescence microscopy
electron microscopy
radioactive-labeled nucleotides
spectrophotometry
labeled kinetochore proteins

Back 8

Radioactive-labeled nucleotides

Front 9

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?

cell wall components and DNA
chlorophyll and cell walls
organelle density and enzymatic activity
organelle density and cell walls
chlorophyll and DNA

Back 9

Organelle density and enzymatic activity

Front 10

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 cells in G2?

The chromosomes would coil and shorten but have no spindle to which to attach.
The cells would be unable to begin M and stay in G2.
The chromosomes would segregate but in a disorderly pattern.
The cells would immediately die.
Each resultant daughter cell would also be unable to form a spindle.

Back 10

The chromosomes would coil and shorten but would have no spindle to which to attach

Front 11

Use the following information to answer the question below.

The lettered circle in the figure shows a diploid nucleus with four chromosomes. There are two pairs of homologous chromosomes, one long and the other short. One haploid set is symbolized as black and the other haploid set is gray. The chromosomes in the unlettered circle have not yet replicated. Choose the correct chromosomal conditions for the following stages.



What is the correct chromosomal condition for one daughter nucleus at telophase of mitosis?
A
B
C
D
E

Back 11

E

Front 12

The following question are based on the figure.



Which number represents DNA synthesis?

I
II
III
IV
V

Back 12

2

Front 13

The following question is based on the figure.



Which number represents the point in the cell cycle during which the chromosomes are being replicated?

I
II
III
IV
V

Back 13

2

Front 14

The following question is based on the figure.



At which of the numbered regions would you expect to find cells at metaphase?

I and IV
II only
III only
IV only
V only

Back 14

3 only

Front 15

The following information applies to the question below.

Several organisms, primarily protists, have what are called intermediate mitotic organization.


These protists are intermediate in what sense?

They reproduce by binary fission in their early stages of development and by mitosis when they are mature.
They use mitotic division but only have circular chromosomes.
None of them form spindles.
They never coil up their chromosomes when they are dividing.
They maintain a nuclear envelope during division.

Back 15

They maintain a nuclear envelope during division

Front 16

The following information applies to the question below.

Several organisms, primarily protists, have what are called intermediate mitotic organization.


What is the most probable hypothesis about these intermediate forms of cell division?

They demonstrate that these species are not closely related to any of the other protists and may well be a different kingdom.
They represent a form of cell reproduction which must have evolved completely separately from those of other organisms.
They rely on totally different proteins for the processes they undergo.
They may be more closely related to plant forms that also have unusual mitosis.
They show some but not all of the evolutionary steps toward complete mitosis.

Back 16

They show some but not all evolutionary steps toward mitosis

Front 17

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 question might be answered by such a method?

How many picograms of DNA are made per cell cycle?
When do spindle fibers attach to chromosomes?
What is the length of the S phase of the cell cycle?
How many cells are produced by the culture per hour?
When is the S chromosome synthesized?

Back 17

What is the length of the S phase during the cell cycle?

Front 18

Use the following information to answer the question below.

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 lymphocyte cultures to skip some parts of the cell cycle.
infection causes lymphocytes to divide more rapidly.
infection causes cell cultures in general to reproduce more rapidly.
their tissue culture methods needed to be relearned.

Back 18

Infection causes lymphocytes to divide more rapidly

Front 19

When a cell is in late anaphase of mitosis, which of the following will we see?
Check all that apply.

breaking down of the nuclear envelope
chromosomes clustered tightly at the center
chromosomes clustered at the poles
a clear area in the center of the cell
individual chromatids beginning to separate from one another

Back 19

A clear area in the center of the cell
Chromosomes clustered at the poles

Front 20

Which of the following is released by platelets in the vicinity of an injury?

MPF
protein kinase
cyclin
Cdk
PDGF

Back 20

PGDF

Front 21

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
Cdk
cyclin
MPF
protein kinase

Back 21

Cyclin

Front 22

Which of the following is a protein maintained at constant levels throughout the cell cycle that requires cyclin to become catalytically active?

Cdk
MPF
PDGF
cyclin
protein kinase

Back 22

CDK

Front 23

Which of the following triggers the cell's passage past the G2 checkpoint into mitosis?

cyclin
PDGF
MPF
Cdk
protein kinase

Back 23

MPF

Front 24

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 protein kinases they produce begin to compete with each other, such that the proteins produced by one cell essentially cancel those produced by its neighbor.
As cells become more numerous, the level of waste products increases, eventually slowing down metabolism.
As cells become more numerous, the cell surface proteins of one cell contact the adjoining cells and they stop dividing.
As cells become more numerous, more and more of them enter the S phase of the cell cycle.

Back 24

As cells become more numerous, the cell surface proteins of one cell contact with the adjoining cells and they stop dividing

Front 25

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.
When they stop dividing, they do so at random points in the cell cycle, and they are not subject to cell cycle controls.
They are not subject to cell cycle controls.
When they stop dividing, they do so at random points in the cell cycle; they are not subject to cell cycle controls; and they do not exhibit density-dependent inhibition when growing in culture.

Back 25

When they stop dividing, they do so at random points in the cell cycle; they are not subject to cell cycle controls; and they do not exhibit density-dependent inhibition when growing in culture

Front 26

Which of the following describe(s) cyclin-dependent kinase (Cdk)?

Cdk is inactive, or "turned off," in the presence of cyclin and it is present throughout the cell cycle.
Cdk is present throughout the cell cycle.
Cdk is inactive, or "turned off," in the presence of cyclin.
Cdk is present throughout the cell cycle and is an enzyme that attaches phosphate groups to other proteins.
Cdk is an enzyme that attaches phosphate groups to other proteins.

Back 26

CDK is present throughout the cell cycle and is an enzyme that attaches phosphate groups to other proteins.

Front 27

Why do neurons and some other specialized cells divide infrequently?

They have been shunted into G0.
They show a drop in MPF concentration.
They no longer carry receptors for signal molecules.
They no longer have active nuclei.
They can no longer bind Cdk to cyclin.

Back 27

They have been shunted into G0

Front 28

At the M phase checkpoint, the complex allows for what to occur?

Cohesins alter separase to allow chromatids to separate.
Daughter cells are allowed to pass into G1.
All microtubules are made to bind to kinetochores.
Separase enzyme cleaves cohesins and allows chromatids to separate.
Kinetochores are able to bind to spindle microtubules.

Back 28

Seperase enzyme cleaves cohesins and allows chromatids to seperate

Front 29

Anchorage dependence of animal cells in vitro or in vivo depends on which of the following?

attachment of spindle fibers to centrioles

the absence of an extracellular matrix

response of the cell cycle controls to signals from the plasma membrane
the binding of cell-surface phospholipids to those of adjoining cells
the binding of cell-surface phospholipids to the substrate

Back 29

Response of the cell cycle controls to signals from the plasma membrane

Front 30

A research team 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 originated in the nervous system.
They were originally derived from an elderly organism.
The cells are unable to form spindle microtubules.
They have altered series of cell cycle phases.
The cells show characteristics of tumors.

Back 30

The cells show characteristics of tumors

Front 31

You have a series of cells, all of which were derived from tumors, and you first need to find out which ones are malignant. What could you do?

See which ones are not overproliferating.
Time their cell cycles.
Karyotype samples to look for unusual size and number of chromosomes.
Measure metastasis.
Find out which ones have a higher rate of apoptosis.

Back 31

Karyotype samples to look for unusual size and number of chromosomes

Front 32

The following question is based on the figure.



MPF reaches its threshold concentration at the end of this stage.

I
II
III
IV
V

Back 32

3