Chapter 12 Quiz- BIO110

Suppose a biologist can separate one of a dozen pieces of chromatin from a eukaryotic (animal) nucleus. It might consist of which of the following? one-twelfth of the genes of the organism a single circular piece of DNA two chromosomes, each with six chromatids two chromatids attached together at a centromere two long strands of DNA plus proteins

two long strands of DNA plus proteins

Where do the microtubules of the spindle originate during mitosis in both plant and animal cells? centriole centromere centrosome kinetochore chromatid

centrosome

One difference between cancer cells and normal cells is that cancer cells cannot function properly because they are affected by density-dependent inhibition. are unable to synthesize DNA. are arrested at the S phase of the cell cycle. continue to divide even when they are tightly packed together. are always in the M phase of the cell cycle.

continue to divide even when they are tightly packed together.

Besides the ability of some cancer cells to overproliferate, what else could logically result in a tumor? metastasis inability to form spindles inability of chromosomes to meet at the metaphase plate changes in the order of cell cycle stages lack of appropriate cell death

lack of appropriate cell death

Movement of the chromosomes during anaphase would be most affected by a drug that prevents shortening of microtubules. prevents attachment of the microtubules to the kinetochore. increases cyclin concentrations. prevents elongation of microtubules. reduces cyclin concentrations.

prevents shortening of microtubules.

At which phase are centrioles beginning to move apart in animal cells? anaphase metaphase telophase prophase prometaphase

prophase

The centromere is a region in which -the nucleus is located prior to mitosis. -metaphase chromosomes become aligned at the metaphase plate. -chromosomes are grouped during telophase. -chromatids remain attached to one another until anaphase. -new spindle microtubules form at either end.

-chromatids remain attached to one another until anaphase.

If there are 20 chromatids in a cell, how many centromeres are there? 40 30 20 10 80

10

For anaphase to begin, which of the following must occur? Cohesin must attach the sister chromatids to each other. Cohesin must be cleaved enzymatically. Chromatids must lose their kinetochores. Spindle microtubules must begin to depolymerize. Kinetochores must attach to the metaphase plate.

Cohesin must be cleaved enzymatically.

A particular cell has half as much DNA as some other cells in a mitotically active tissue. The cell in question is most likely in metaphase. anaphase. G1 prophase. G2

G1

Which of the following are primarily responsible for cytokinesis in plant cells but not in animal cells? cyclin-dependent kinases centrioles and centromeres actin and myosin Golgi-derived vesicles kinetochores

Golgi-derived vesicles

Which of the following most accurately describes a cyclin? It decreases in concentration when MPF activity increases. It is activated to phosphorylate by complexing with a Cdk. It is present in similar concentrations throughout the cell cycle. It activates a Cdk when its concentration is decreased. It activates a Cdk molecule when it is in sufficient concentration.

It activates a Cdk molecule when it is in sufficient concentration.

The cyclin component of MPF is destroyed toward the end of which phase? G2 G0 S G1 M

M

Which of the following triggers the cell's passage past the G2 checkpoint into mitosis? cyclin protein kinase Cdk PDGF MPF

MPF

A mutation results in a cell that no longer produces a normal protein kinase for the M phase checkpoint. Which of the following would likely be the immediate result of this mutation? The cell would never leave metaphase. The cell would undergo normal mitosis, but fail to enter the next G1 phase. The cell would never enter metaphase. The cell would never enter prophase. The cell would prematurely enter anaphase.

The cell would undergo normal mitosis, but fail to enter the next G1 phase.

Which of the following best describes how chromosomes move toward the poles of the spindle during mitosis? The chromosomes are "reeled in" by the contraction of spindle microtubules, motor proteins of the kinetochores move the chromosomes along the spindle microtubules, and nonkinetochore spindle fibers serve to push chromosomes in the direction of the poles. The chromosomes are "reeled in" by the contraction of spindle microtubules. The chromosomes are "reeled in" by the contraction of spindle microtubules, and motor proteins of the kinetochores move the chromosomes along the spindle microtubules. Motor proteins of the kinetochores move the chromosomes along the spindle microtubules. Nonkinetochore spindle fibers serve to push chromosomes in the direction of the poles.

The chromosomes are "reeled in" by the contraction of spindle microtubules, and motor proteins of the kinetochores move the chromosomes along the spindle microtubules.

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 bacterial cell dividing. an animal cell in the S phase of the cell cycle. a plant cell in metaphase. an animal cell in the process of cytokinesis. a plant cell in the process of cytokinesis.

a plant cell in the process of cytokinesis.

The MPF protein complex turns itself off by activating the anaphase-promoting complex. activating an enzyme that stimulates cyclin. exiting the cell. binding to chromatin. activating a process that destroys cyclin components.

activating a process that destroys cyclin components.

Which of the following does not occur during mitosis? separation of sister chromatids replication of the DNA condensation of the chromosomes spindle formation cell cycles lacking an S phase.

replication of the DNA

Why do chromosomes coil during mitosis? to allow the chromosomes to move without becoming entangled and breaking to provide for the structure of the centromere to allow the chromosomes to fit within the nuclear envelope to increase their potential energy to allow the sister chromatids to remain attached

to allow the chromosomes to move without becoming entangled and breaking