Chapter 12 MB

Spindle fibers attach to kinetochores during _____. a. anaphase b. metaphase c. prometaphase d. telophase e. interphase

c. prometaphase

Which of the following does NOT occur during mitosis? a. condensation of the chromosomes b. replication of the DNA c. separation of the spindle poles d. spindle formation

b. replication of the DNA

Starting with a fertilized egg (zygote), a series of five cell divisions would produce an early embryo with how many cells? a. 64 b. 32 c. 16 d. 8

b. 32

In eukaryotic cells, chromosomes are composed of _____. a. DNA and RNA b. DNA and proteins c. DNA and phospholipids d. DNA only

b. DNA and proteins

Why is it difficult to observe individual chromosomes with a light microscope during interphase? a. Sister chromatids do not pair up until division starts. b. They have uncoiled to form long, thin strands. c. The spindle must move them to the metaphase plate before they become visible. d. The DNA has not been replicated yet. e. They leave the nucleus and are dispersed to other parts of the cell.

b. They have uncoiled to form long, thin strands.

During which phase of mitosis do the chromatids become chromosomes? a. telophase b. anaphase c. prophase d. metaphase

b. anaphase

Kinetochore microtubules assist in the process of splitting centromeres by _____. a. sliding past each other like actin filaments b. creating tension by pulling toward opposite poles c. phosphorylating the centromere, thereby changing its conformation d. using motor proteins to split the centromere at specific arginine residues

b. creating tension by pulling toward opposite poles

At which phase are centrioles beginning to move apart in animal cells? a. metaphase b. prophase c. anaphase d. prometaphase

b. prophase

Which of the following correctly matches a phase of the cell cycle with its description? a. G1: follows cell division b. G2: cell division c. M: duplication of DNA d. S: immediately precedes cell division e. All of the above are correctly matched.

a. G1: follows cell division

If there are 20 centromeres in a cell at anaphase, how many chromosomes are there in each daughter cell following cytokinesis? a. 10 b. 20 c. 80 d. 40

a. 10

If there are 20 duplicated chromosomes in a cell, how many centromeres are there? a. 20 b. 40 c. 30 d. 10

a. 20

Which of the following is found in binary fission but not in mitosis? a. Duplicated chromosomes attach to the plasma membrane. b. Replicated strands of DNA separate. c. Replication of DNA begins at an origin. d. The result produces 2 nuclei. e. Following the process, a membrane separates the 2 copies.

a. Duplicated chromosomes attach to the plasma membrane.

Which of the following is true of kinetochores? a. They are sites at which microtubules attach to chromosomes. b. They attach to the ring of actin along the cytoplasmic surface of the plasma membrane, causing the actin to contract to form the cleavage furrow. c. They are located at the center of the centrosome; their function is to organize tubulin into elongated bundles called spindle fibers. d. They interdigitate at the cell's equator and then move apart, causing the cell to elongate. e. They are the primary centromere structures that maintain the attachment of the sister chromatids prior to mitosis.

a. They are sites at which microtubules attach to chromosomes.

The microtubule-organizing center found in animal cells is an identifiable structure present during all phases of the cell cycle. Specifically, it is known as the _____. a. centrosome b. kinetochore c. centromere d. microtubulere

a. centrosome

What is the final result of mitosis in a human? a. genetically identical somatic cells containing 46 chromosomes b. genetically different somatic cells containing 46 chromosomes c. genetically identical gamete cells containing 46 chromosomes d. genetically identical somatic cells containing 23 chromosomes

a. genetically identical somatic cells containing 46 chromosomes

Cytokinesis often, but not always, accompanies _____. a. telophase b. interphase c. metaphase d. anaphase e. prometaphase

a. telophase

In human and many other eukaryotic species' cells, the nuclear membrane has to disappear to permit _____. a. the attachment of microtubules to kinetochores b. the disassembly of the nucleolus c. the splitting of the centrosomes d. cytokinesis

a. the attachment of microtubules to kinetochores

Metaphase is characterized by _____. a. splitting of the centromeres b. cytokinesis c. aligning of chromosomes on the equator d. separation of sister chromatids

c. aligning of chromosomes on the equator

Centromeres divide and sister chromatids become full-fledged chromosomes during _____. a. telophase b. prometaphase c. anaphase d. metaphase e. interphase

c. anaphase

How is plant cell cytokinesis different from animal cell cytokinesis? a. The contractile filaments found in plant cells are structures composed of carbohydrates; the cleavage furrow in animal cells is composed of contractile phospholipids. b. The structural proteins of plant cells separate the two cells; in animal cells, a cell membrane separates the two daughter cells. c. Plant cells divide after metaphase but before anaphase; animal cells divide after anaphase. d. Plant cells deposit vesicles containing cell-wall building blocks on the metaphase plate; animal cells form a cleavage furrow.

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

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. a plant cell in metaphase b. an animal cell in the S phase of the cell cycle c. an animal cell in the process of cytokinesis d. a plant cell in the process of cytokinesis

d. a plant cell in the process of cytokinesis

Nucleoli are present during _____. a. metaphase b. prophase c. prometaphase d. interphase e anaphase

d. interphase

The mitotic spindle is a microtubular structure that is involved in _____. a. splitting of the cell (cytokinesis) following mitosis b. dissolving the nuclear membrane c. triggering the compaction and condensation of chromosomes d. separation of sister chromatids

d. separation of sister chromatids

Taxol is an anticancer drug extracted from the Pacific yew tree. In animal cells, Taxol disrupts microtubule formation. Surprisingly, this stops mitosis. Specifically, Taxol must affect _____. a. anaphase b. chromatid assembly c. formation of the centrioles d. the structure of the mitotic spindle

d. the structure of the mitotic spindle

During prophase a homologous pair of chromosomes consists of _____. a. four chromosomes and two chromatids b. one chromosome and four chromatids c. one chromosome and two chromatids d. two chromosomes and four chromatids e. two chromosomes and two chromatids

d. two chromosomes and four chromatids

Chromosomes become visible during _____. a. metaphase b. anaphase c. prometaphase d. interphase e. prophase

e. prophase