Biology HW Chapter 8

A diploid organism whose somatic (nonsex) cells each contain 32 chromosomes produces gametes containing _____ chromosomes.

16

Asexual reproduction requires ________ individual(s), whereas sexual reproduction requires _______ individual(s).

1; 2

Normal human gametes carry _____ chromosomes.

23

A human bone marrow cell in the prophase stage of mitosis contains 46 chromosomes. Therefore, there are a total of __________ sister chromatids in this cell.

92

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

Anaphase

Which of these cells is (are) haploid?

C and D

Which of the following statements regarding cell division is false?

Cell division is common in eukaryotes but rare in prokaryotes.

Which of the following statements correctly describes the timing of DNA synthesis?

DNA is synthesized in the S phase of interphase.

A skin cell of a red fox has 34 chromosomes. You look at the cell under a microscope and see that it has 34 chromosomes and one nucleus. Several hours later, you look at the same cell again and see that it has double the amount of DNA and one nucleus. A little while later, you see that it has 68 chromosomes and two nuclei. What stage of the cell cycle was this cell in when you viewed it at each time point?

First view: G1; second view: G2; third view: telophase

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

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

Metaphase

Which of the following statements regarding sexual and asexual reproduction is true?

Sexual reproduction is more likely to increase genetic variation than is asexual reproduction.

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

Telophase

Which of the following is a feature of plant cell division that distinguishes it from animal cell division?

formation of a cell plate

Consider the photograph shown below. You can determine this is a plant cell rather than an animal cell because it has __________.

formed a cell plate

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

four ... haploid

Meiosis starts with a single diploid cell and produces

four haploid cells.

During prophase I of meiosis,

homologous chromosomes stick together in pairs.

Chromatids are _____.

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

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

interphase

Eukaryotic cells spend most of their cell cycle in which phase?

interphase

Nucleoli are present during _____.

interphase

A cell preparing to undergo meiosis duplicates its chromosomes during

interphase.

Sister chromatids are

joined together at a centromere.

Gametes are produced by _____.

meiosis

During which phase of mitosis do the chromosomes line up on a plane equidistant from the two spindle poles?

metaphase

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

metaphase II

During meiosis, homologous chromosomes sometimes "stick together" and do not separate properly. This phenomenon is known as _____.

nondisjunction

A cell that has a cell wall is undergoing cell division, and the following events are observed: the formation of a cell plate and the division of the cell into two daughter cells. What type of cell is being observed and what process(es) is it going through?

plant cell; telophase and cytokinesis of mitosis

Asexual reproduction _____.

produces offspring genetically identical to the parent

The term binary fission is best applied to _____.

prokaryotes

Spindle fibers attach to kinetochores during _____.

prometaphase

Chromosomes become visible during _____.

prophase

In the telophase of mitosis, the mitotic spindle breaks down and the chromatin uncoils. This is essentially the opposite of what happens in _____.

prophase

Many cancer drugs known as "antimitotics" target microtubules. What is the first stage of mitosis at which these drugs are likely to have an effect?

prophase

Synapsis occurs during _____.

prophase I

The correct order of events during meiosis is

prophase I, metaphase I, anaphase I, telophase I, cytokinesis, meiosis II.

At the start of mitotic anaphase,

the centromeres of each chromosome come apart.

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

the mitotic phase

During mitosis, the chromosomes move because _____.

they attach to a dynamic, precisely regulated mitotic spindle

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

two ... haploid

Looking into your microscope, you spot an unusual cell. Instead of the typical rounded cell shape, the cell has a very narrow middle separating two bulging ends. It sort of looks like the number 8! You realize that this cell is

undergoing cytokinesis.

During _____ sister chromatids separate.

anaphase II

During meiosis, segments of nonsister chromatids can trade places. This recombination of maternal and paternal genetic material is a key feature of meiosis. During what phase of meiosis does recombination occur?

prophase I.

During _____ a spindle forms in a haploid cell.

prophase II

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

anaphase

What event will immediately follow the event shown in this image?

The cell will divide into two plant cells.

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.

Within one chromosome, what is the relationship between the sequence of bases in DNA of one sister chromatid compared to the other?

The sequences are identical.

You are observing a single cell under a microscope. You go home for the night, and the next day you see four cells. The four cells look similar, and when you stain them with a dye that binds to DNA they all appear to contain the same amount of DNA as the original cell. What likely happened overnight?

The single cell divided to form two new cells, and the two new cells each divided to form four total cells, all by asexual reproduction.

Which of the following occurs during mitosis?

Two daughter nuclei, one at each pole of the cell, are generated.

mitosis meiosis I only centromere 10 the start of meiosis I

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With the exception of identical twins, siblings who have the same two biological parents are likely to look similar, but not identical, to each other because they have

a similar but not identical combination of genes.

What is different concerning the DNA in bacterial cells as opposed to eukaryotic cells?

all of the above are differences between prokaryotic and eukaryotic DNA

Homologous chromosomes migrate to opposite poles during _____.

anaphase I

Bacteria divide by:

binary fission

Karyotyping

can reveal alterations in chromosome number.

Which of the following occurs during interphase?

cell growth and duplication of the chromosomes

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

cytokinesis

As a patch of scraped skin heals, the cells fill in the injured area but do not grow beyond that. This is an example of

density-dependent inhibition.

A benign tumor differs from a malignant tumor in that a benign tumor

does not metastasize.

The phase of mitosis during which the mitotic spindle begins to form is

prophase.

Prior to mitosis and after S phase, each chromosome of a eukaryotic cell consists of a pair of identical structures called

sister chromatids.

The kinetochores are __________.

sites at which microtubules attach to chromosomes

Cytokinesis often, but not always, accompanies _____.

telophase

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

telophase II

The first step of bacterial replication is _____.

DNA replication

Which of these phases encompasses all of the stages of mitosis?

E

Eukaryotic chromosomes differ from prokaryotic chromosomes in that they

are housed in a membrane-enclosed nucleus.

In many organisms, including humans, chromosomes are found in homologous pairs. Homologous chromosomes _____.

are identical in the arrangement of their genes, but some versions of the genes may differ between the chromosomes

Mature human neuron (nerve) cells and muscle cells

are permanently in a state of nondivision.

What name is given to this process?

asexual reproduction

The creation of genetically identical offspring by a single parent, without the participation of sperm and egg, is called

asexual reproduction.

A cell replicates its entire chromosomal DNA only __________.

before it is about to divide

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

telophase I

DNA replication occurs in _____.

the S phase of interphase

During prophase a homologous pair of chromosomes consists of _____.

two chromosomes and four chromatids