chapter 12 mastering

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Which of the following statements best describes how cytokinesis differs between plant and animal cells?

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

discrete chromosomes are now visible; each consists of two aligned, identical sister chromatids. Later the nuclear envelope will fragment.

Prometaphase

the chromosomes are condensing and the nucleolus is beginning to disappear. The mitotic spindle is starting to form

Prophase

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___ 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

Cytochalasin B is a chemical that disrupts microfilament formation. With which aspect of cell division would cytochalasin B interfere?

cleavage

If there are 24 centromeres in a cell at anaphase of mitosis, how many chromosomes will be found in each daughter cell following cytokinesis?

12

Which of the following properties is associated with a cyclin-dependent kinase (Cdk)?

A Cdk is an enzyme that attaches phosphate groups to other proteins.

the chromatids of each chromosome have separated, and the daughter chromosomes are moving to the ends of the cell as their kinetochore microtubules shorten.

Anaphase

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

Which of the following events characterizes the beginning of anaphase?

enzymatic cleavage of cohesin

Eukaryotic chromatin is composed of which of the following macromolecules?

DNA and proteins

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

During interphase, a cell is metabolically active.

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.

Cell A has half as much DNA as cells B, C, and D in a mitotically active tissue. Cell A 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 of the following correctly matches a phase of the cell cycle with its description?

G1, follows cell division

Nucleoli are present during _____.

Interphase

he spindle is complete, and the chromosomes, attached to microtubules at their kinetochores, are all at the plate.

Metaphase

daughter nuclei are forming. Cytokinesis has started: The cell plate, which will divide the cytoplasm in two, is growing toward the perimeter of the parent cell.

Telophase

Which of the following statements best describes cells in culture that do not exhibit either density-dependent inhibition or anchorage dependence?

The cells show characteristics of tumors.

Which of the following statements describing kinetochores is correct?

They are sites at which microtubules attach to chromosomes.

Which of the following statements best describes 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.

Which of the following statements describes a characteristic feature of metaphase?

alignment of chromosomes on the equator of the cell

Centromeres divide and sister chromatids become full-fledged chromosomes during _____.

anaphase

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

centromere(s)

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

In most eukaryotes, division of the nucleus is followed by___when the rest of the cell divides.

cytokinesis

During telophase, the nonkinetochore microtubules___

disassemble

Students in a biology lab isolated cells in various phases of the cell cycle. A population of cells that have 1 1/2 times the DNA of G1 phase cells was most likely isolated from which of the following parts of the cell cycle?

in the S phase

During _____ the cell grows and replicates both its organelles and its chromosomes.

interphase

Why is it difficult to observe individual chromosomes with a light microscope during interphase?

interphase chromosomes are long, thin strands unlike the condensed chromosomes visible in mitosis

In dividing cells, most of the cell's growth occurs during____

interphase.

During mitosis, microtubules attach to chromosomes at the____

kinetochore(s)

During prophase, the microtubules of the mitotic spindle___

lengthen

During anaphase, the nonkinetochore microtubules___ and move past each other, and the kinetochore microtubules____

lengthen, shorten

The mitotic phase encompasses both

mitosis and cytokinesis

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

mitotic spindle(s)

Which of the following cellular events occur in the G1 phase of the cell division cycle?

normal growth and cell function

Spindle fibers attach to kinetochores during _____.

prometaphase

Chromosomes become visible during _____.

prophase

Which of the following occurs during S phase?

replication of the DNA

The mitotic spindle plays a critical role in which of the following processes?

separation of sister chromatids

Movement of the chromosomes during anaphase would be most directly affected by a drug that prevents which of the following events?

shortening of microtubules

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

sister chromatid(s)

After DNA replication, each duplicated chromosome consists of two of which of the following structures?

sister chromatids

Cytokinesis often, but not always, accompanies _____.

telophase

What is the name of the region on duplicated chromosomes where the sister chromatids are most closely attached to each other?

the centromere

During _____ both the contents of the nucleus and the cytoplasm are divided.

the mitotic phase


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