Chapter 12 - Mastering Biology Questions :()))

Which statement provides the best description of the interphase portion of the cell cycle?

During interphase, a cell is metabolically active.

Which of the following correctly matches a phase of the cell cycle with its description?

G1: follows cell division

In the figure above, at which of the numbered regions would you expect to find cells at metaphase?

III only

The M-phase checkpoint ensures that all chromosomes are attached to the mitotic spindle. If this does not happen, cells would most likely be arrested in _____.

metaphase

The ____________________ is a cell structure consisting of microtubules, which forms during early mitosis and plays a role in cell division.

mitotic spindle(s)

The first gap in the cell cycle (G1) corresponds to _____.

normal growth and cell function

At which phase are centrioles beginning to move apart in animal cells?

prophase

DNA replication produces two identical DNA molecules, called _______________, which separate during mitosis.

sister chromatid(s)

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

10

Density-dependent inhibition is explained by which of the following?

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

What is the correct chromosomal condition at prometaphase of mitosis?

B

How do cancer cells differ from normal cells?

Cancer cells may be immortal.

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

Cohesion is cleaved enzymatically.

Cells will usually divide if they receive the proper signal at a checkpoint in which phase of the cell cycle?

G1

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.

In the figure above, which number represents DNA synthesis?

II

The cyclin component of MPF is destroyed toward the end of which phase?

M

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

MPF

How is plant cell cytokinesis different from animal cell cytokinesis?

Plant cells deposit vesicles containing cell-wall building blocks on the metaphase plate; animal cells form a cleavage furrow.

What happens if MPF (mitosis-promoting factor) is introduced into immature frog oocytes that are arrested in G2?

The cells enter mitosis.

Once a cell completes mitosis, molecular division triggers must be turned off. What happens to MPF during mitosis?

The cyclin component of MPF is degraded.

Which of the following is true of benign tumors, but not malignant tumors?

They remain confined to their original site

A cleavage furrow is _____.

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

During which phase of mitosis do the chromatids become chromosomes?

anaphase

Metaphase is characterized by _____.

aligning of chromosomes on the equator

Cyclin-dependent kinase (Cdk) is _____.

an enzyme that attaches phosphate groups to other proteins

In the cells of some organisms, mitosis occurs without cytokinesis. This will result in?

cells with more than one nucleus.

After chromosomes condense, the ____________ is the region where the identical DNA molecules are most tightly attached to each other.

centromere(s)

The _________________ are the organizing centers for microtubules involved in separating chromosomes during mitosis.

centrosome(s)

During interphase, most of the nucleus is filled with a complex of DNA and protein in a dispersed form called ______________.

chromatin

The drug cytochalasin B blocks the function of actin. Which of the following aspects of the cell cycle would be most disrupted by cytochalasin B?

cleavage furrow formation and cytokinesis

Kinetochore microtubules assist in the process of splitting centromeres by _____.

creating tension by pulling toward opposite poles

In most eukaryotes, division of the nucleus is followed by _________________, when the rest of the cell divides.

cytokinesis

Neurons and some other specialized cells divide infrequently because they _____.

have entered into G0

Scientists isolate cells in various phases of the cell cycle. They find a group of cells that have 1.5 times more DNA than G1 phase cells. The cells of this group are _____.

in the S phase of the cell cycle

In dividing cells, most of the cell's growth occurs during __________________.

interphase

During mitosis, microtubules attach to chromosomes at the _________________.

kinetochore(s)

Besides the ability of some cancer cells to overproliferate, what else could logically result in a tumor?

lack of appropriate cell death

Which of the following does NOT occur during mitosis?

replication of the DNA

Which of the following does not occur during mitosis?

replication of the DNA

Movement of the chromosomes during anaphase would be most affected by a drug that prevents _____.

shortening of microtubules