Chapter 8 mastering biology

What is the risk that someone in the United States will have cancer sometime in their lifetime?

1 in 3

A fruit fly somatic cell contains 8 chromosomes. This means that ______________ different combinations of chromosomes are possible in its gametes.

16

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

G1

The centrosomes move away from each other and the nuclear envelope breaks up during which phase of mitosis?

Prophase

What must happen before a cell can begin mitosis?

The chromosomes must be duplicated.

What would be the immediate consequence of destroying a cell's centrosomes?

The mitotic spindle would not form.

Although in humans there are 22 pairs of autosomal chromosomes, only three different chromosomal trisomies are commonly seen in newborns. Of the remaining 19 autosomes, many trisomies have not been seen in newborns. Why not?

Trisomy for the other autosomal chromosomes is often lethal, and the affected embryos are miscarried.

During _____ sister chromatids separate.

anaphase II

Synapsis occurs during _____.

prophase I

During _____ a spindle forms in a haploid cell.

prophase II

Which of the following is the correct order for the four main stages of mitosis?

prophase, metaphase, anaphase, telophase

Meiosis I produces _____ cells, each of which is _____.

two ... haploid

What is the difference between a benign tumor and a malignant tumor?

Benign tumors do not metastasize; malignant tumors do.

When examining cells in the laboratory, you notice that a particular cell has half as much DNA as the surrounding cells. This observation can be explained if this cell's cell cycle halted at checkpoint _____.

G1

Immune system cells enter a resting phase after undergoing mitosis. When activated—for example, by an infection—they can reenter the sequence of events in the cell cycle that leads to cell division. What would be the correct cell cycle sequence of events for these reactivated cells?

G1, S, G2, M

_________________ is the spread of cancer cells from their site of origin to other sites in the body.

Metastasisis

Which of the following is a normal human female?

XX

The sister chromatids separate and begin moving toward opposite poles of the cell during which phase of mitosis?

anaphase

Homologous chromosomes migrate to opposite poles during _____.

anaphase I

Replication of chromosomal DNA occurs __________.

before a cell divides

A_______________is a lump of abnormal cells that, although growing out of control, remains at its original site.

benign tumor

A biochemist measured the amount of DNA in cells growing in the laboratory and found that the quantity of DNA in a cell doubled

between the G1 and G2 phases of the cell cycle.

An individual with a malignant tumor is said to have_____________

cancer

The most common type of cancer is a__________________; this type always originates in tissues that line organs.

carcinoma

A benign and a malignant tumor differ in that _____.

cells of a benign tumor remain within the tumor, whereas cells of a malignant tumor can spread to other body tissues

At the end of the mitotic (M) phase, the cytoplasm divides in a process called _________________.

cytokinesis

Meiosis II typically produces _____ cells, each of which is _____.

four ... haploid

Meiosis and cytokinesis result in the formation of __________.

four haploid cells

Chromatids are _____.

identical copies of each other if they are part of the same chromosome

A__________________is an abnormally growing mass of cells that is actively spreading through the body.

malignant tumor

The chromosomes line up in the center of the cell during which phase of mitosis?

metaphase

During _____ chromosomes align single file along the equator of a haploid cell.

metaphase II

Which of the following shows mitosis in the correct chronological order?

prophase, prometaphase, metaphase, anaphase, telophase

In meiosis II, _____.

sister chromatids separate

The chromosomes arrive at the poles and nuclear envelopes form during which phase of mitosis?

telophase

At the end of _____ and cytokinesis, haploid cells contain chromosomes that each consist of two sister chromatids.

telophase I

At the end of _____ and cytokinesis there are four haploid cells.

telophase II

It is difficult to observe individual chromosomes during interphase because

they are in the form of long, thin strands.

Mitosis and cytokinesis result in the formation of __________; meiosis and cytokinesis result in the formation of __________.

two diploid cells : four haploid cells