Chapter 12 quiz

f 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) 30 D) 40 E) 80

A) 10

In the cells of some organisms, mitosis occurs without cytokinesis. This will result in A) cells with more than one nucleus. B) cells that are unusually small. C) cells lacking nuclei. D) destruction of chromosomes. E) cell cycles lacking an S phase

A) cells with more than one nucleus.

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

A) chromatids remain attached to one another until anaphase.

Vinblastine is a standard chemotherapeutic drug used to treat cancer. Because it interferes with the assembly of microtubules, its effectiveness must be related to A) disruption of mitotic spindle formation. B) inhibition of regulatory protein phosphorylation. C) suppression of cyclin production. D) myosin denaturation and inhibition of cleavage furrow formation. E) inhibition of DNA synthesis.

A) disruption of mitotic spindle formation.

During which phase of mitosis do the chromatids become chromosomes? A) telophase B) anaphase C) prophase D) metaphase E) cytokinesis

A) telophase

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 A) the formation of the mitotic spindle. B) anaphase. C) formation of the centrioles. D) chromatid assembly. E) the S phase of the cell cycle.

A) the formation of the mitotic spindle.

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

B) to allow the chromosomes to move without becoming entangled and breaking

Cells from an advanced malignant tumor most often have very abnormal chromosomes, and often an abnormal total number of chromosomes. Why might this occur? A) Cancer cells are no longer density dependent. B) Cancer cells are no longer anchorage dependent. C) Chromosomally abnormal cells can still go through cell cycle checkpoints. D) Chromosomally abnormal cells still have normal metabolism. E) Transformation introduces new chromosomes into cells.

C) Chromosomally abnormal cells can still go through cell cycle checkpoints.

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

C) Karyotype samples to look for unusual size and number of chromosomes.

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

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

What is a cleavage furrow? A) a ring of vesicles forming a cell plate B) the separation of divided prokaryotes C) a groove in the plasma membrane between daughter nuclei D) the metaphase plate where chromosomes attach to the spindle E) the space that is created between two chromatids during anaphase

C) a groove in the plasma membrane between daughter nuclei

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

C) lack of appropriate cell death

The research team established similar lymphocyte cultures from a number of human donors, including healthy teenagers of both genders, patients already suffering from long-term bacterial infections, and elderly volunteers. They found that the increase in lymphocyte incorporation after pathogen introduction was slightly lower in some of the female teenagers and significantly lower in each of the elderly persons. They repeated the study with a larger number of samples but got the same results. Which of the following investigations might be most productive to show what the data on the teenagers might indicate? A) test male teenagers B) test teenagers who say they are not sexually active C) test female teens at different times in their menstrual cycles D) test relatives of the teens previously tested E) test teenagers from different school systems

C) test female teens at different times in their menstrual cycles

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

D) The cells show characteristics of tumors.

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. Once they had determined which cells were dividing, the team wanted to use a non-radioactive method to track whether various physiological factors (such as food or body temperature) affect the action of the pathogen. Which of the following would be effective, simple, and safe? A) measuring picograms of DNA B) measuring numbers of chromosomes C) measuring numbers of chromatids D) counting the frequency of cells in mitosis E) counting newly formed plasma membranes

D) counting the frequency of cells in mitosis

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

D) prevents shortening of microtubules.

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

E) They show some but not all of the evolutionary steps toward complete mitosis.

Which of the following is true concerning cancer cells? A) They do not exhibit density-dependent inhibition when growing in culture. B) When they stop dividing, they do so at random points in the cell cycle. C) They are not subject to cell cycle controls. D) When they stop dividing, they do so at random points in the cell cycle, and they are not subject to cell cycle controls. E) 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.

E) 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.

Proteins that are involved in the regulation of the cell cycle, and that show fluctuations in concentration during the cell cycle, are called A) ATPases. B) kinetochores. C) kinases. D) proton pumps. E) cyclins.

E) cyclins.

At which phase are centrioles beginning to move apart in animal cells? A) telophase B) anaphase C) prometaphase D) metaphase E) prophase

E) prophase