Biology Chapter 8

An example of a cell that is 2n is a __________.

Somatic Cell

During which phase of mitosis does the nuclear envelope re-form?

Telophase

Which of the following statements regarding the cell cycle control system is false?

The cell cycle control system operates independently of the growth factors.

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

The cell will divide into two plant cells.

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

The mitotic spindle would not form.

Chromatids are ______.

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

A fragment of chromosome 21 reattaches to chromosome 21, but in the reverse direction. What is the name given to this change?

Inversion

During binary fission, each copy of the duplicating chromosome moves to opposite ends of the cell. What does this achieve?

It ensures that each daughter cell receives one copy of the chromosome.

Which of the following statements correctly describes the behavior of a tetrad during anaphase I of meiosis?

It splits into two pairs of sister chromatids, and one pair goes to each pole of the dividing cell.

Nondisjunction occurs when

Members of a chromosome pair fail to separate.

The term binary fission is best applied to _____.

Prokaryotes

Which of the following helps maintain the structure of chromosomes and control the activity of genes?

Proteins

Prior to mitosis, each chromosome of a eukaryotic cell consists of a pair of identical structures called

Sister Chromatids

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

Which of the following occurs during interphase?

cell growth and duplication of the chromosomes

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

When we say that an organism is haploid, we mean that _____.

its cells each have one set of chromosomes

How many pairs of autosomes do humans have?

22

In a cell containing 10 chromosomes, meiosis results in the formation of daughter cells containing _____ chromosomes.

5

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

Imagine that a human skin cell went through mitosis but did not undergo cytokinesis. How many chromosomes would be in the cell?

92

A cell replicates its entire chromosomal DNA only __________.

Before it is about to divide

In the laboratory, cancer cells fail to show density-dependent inhibition of growth in cell culture. What is one explanation that could account for this?

Cancer cells continuously secrete growth factors into the cell culture medium.

During meiosis I, homologous chromosomes form a tetrad and crossing over occurs. What is the outcome of crossing over?

Crossing over creates new combinations of genes present on a single chromosome.

The process by which the cytoplasm of a eukaryotic cell divides to produce two cells is called

Cytokisnesis

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

DNA is synthesized in the S phase of interphase.

When animal cells are grown in a petri dish, they typically stop dividing once they have formed a single, unbroken layer on the bottom of the dish. This arrest of division is an example of

Density-dependent inhibition

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

Formation of a cell plate

In theory, when a nondisjunction for chromosome 18 occurs during meiosis I, four gametes can be produced. If these gametes are fertilized with unaffected gametes from the second parent, what observations would you make concerning the resulting embryos?

Two of the embryos will be trisomic for chromosome 18, and two will contain a single copy of chromosome 18

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

Which of the following is a normal human female?

XX

The function of meiosis is to make __________.

four cells with a haploid number of chromosomes

At the conclusion of meiosis I, the daughter cells are _____.

haploid and the sister chromatids are joined

The exchange of parts between nonhomologous chromosomes is called _____.

reciprocal translocation

Down syndrome can be the result of _____.

nondisjunction of chromosome 21 during meiosis

In meiosis II, _____.

sister chromatids are separated

At the start of mitotic anaphase,

the centromeres of each chromosome come apart.

Crossing over is _____.

the exchange of homologous portions of nonsister chromatids

Which of the following statements regarding mitosis and meiosis is false?

Mitosis produces daughter cells with half the number of chromosomes as the parent cell.

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

Nondisjunction

Both mitosis and meiosis are preceded by

Interphase

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

Interphase

If a fragment of a chromosome breaks off and then reattaches to the original chromosome at the same place but in the reverse direction, the resulting chromosomal abnormality is called _____.

An inversion

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

Asexual Reproduction

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

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

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

Independent orientation of chromosomes at metaphase I results in an increase in the number of

possible combinations of characteristics.

During which stage of meiosis do synapsis and crossing over occur?

prophase I

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

prophase, prometaphase, metaphase, anaphase, telophase