bio chapter 8

Which of the following checkpoints does not occur late in G1?

A check that chromosome replication has been successfully completed

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

Malignant tumor

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

Metastasis

Karyotyping

can reveal alterations in chromosome number.

An individual with a malignant tumor is said to have ______

cancer

Meiosis differs from mitosis in that _____ only occurs in meiosis.

crossing over ---- Crossing over, the exchange of corresponding segments between nonsister chromatids of homologous chromosomes, only occurs during meiosis.

In anaphase I, __________

homologous chromosomes move toward opposite poles

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

its cells each have one set of chromosomes

Variation occurs when chromosomes are shuffled in _____.

meiosis

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

metaphase

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

1; 2

A certain species of animal has six pairs of chromosomes. How many DNA molecules are present in the nuclei of these animals during G2 phase?

24

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

Benign tumor

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

Carcinoma

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

DNA is synthesized in the S phase of interphase.

True or false. Mitosis takes place during M phase of the cell cycle, which is longer than interphase

False

Which of the following statements regarding genetic diversity is false?

Genetic diversity is enhanced by mitosis

How many pairs of autosomes do humans have?

Humans have 22 pairs of autosomes and one pair of sex chromosomes.

Which of the following is a normal human female?

XX

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

does not metastasize

After fertilization, the resulting zygote begins to divide by __________.

mitosis

During anaphase II, _____.

sister chromatids separate and migrate toward opposite poles

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

telophase

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

two diploid cells : four haploid cells --- In mitosis, a cell that has doubled its genetic material divides into two diploid daughter cells. In meiosis, a cell that has doubled its genetic material undergoes two rounds of division, resulting in the production of four haploid cells.

A cell biologist carefully measured the quantity of DNA in grasshopper cells growing in cell culture. Cells examined during the G2 phase of the cell cycle contained 200 units of DNA. What would be the amount of DNA in one of the grasshopper daughter cells?

100 units -- Recall that G2 follows S, and that during the S phase, DNA is replicated. Then, chromatids are separated during mitosis to form daughter cells

When observing a chicken skin cell in G2 under a microscope, you count 156 total chromatids. How many chromosomes does a male chicken have in its sperm cells?

39

Trisomy for most autosomes is fatal, yet trisomy or even tetrasomy (four copies) of the X chromosome is not. What is the explanation for this difference?

Only one copy of the X chromosome is functional, regardless of the total number of X chromosomes.

Which of the following variations of the sentence "Where is the cat?" is most like a chromosomal deletion?

Where is cat?

A pair of sex chromosomes found in a human male is most like

a bride and groom

Crossing over is important because it _____. Crossing over is important because it _____.

allows the exchange of genes between homologous chromosomes

The stage of mitosis during which the chromosomes move toward separate poles of the cell is _____.

anaphase

A cleavage furrow forms in an animal cell during _____.

cytokinesis

In bacterial cells, binary fission involves __________.

distribution of a copy of the single parental chromosome to each daughter cell

The diploid phase of the human life cycle begins with _____.

fertilization

Which of the following types of organisms commonly demonstrates polyploidy?

flowering plants

What is the typical result when a diploid cell undergoes meiosis?

four haploid cells

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

haploid and the sister chromatids are joined

Two chromosomes in a nucleus that carry genes controlling the same inherited characteristics are

homologous chromosomes

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

interphase

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

inversion

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

nondisjunction

Down syndrome can be the result of _____.

nondisjunction of chromosome 21 during meiosis

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

prophase

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

prophase

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

prophase I

Crossing over occurs during _____.

prophase I --During prophase I of meiosis, homologous chromosomes pair up and can exchange genetic information.

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

prophase, prometaphase, metaphase, anaphase, telophase

In humans, the haploid number of chromosomes is 23. Independent assortment has the possibility of producing __________ different gametes.

2^23 ------ For each gamete, there are two possibilities for each chromosome (the paternal or the maternal chromosome), and there are 23 different chromosomes per gamete

A human somatic cell contains _____ chromosomes.

46 ---- Human somatic cells contain 22 pairs of nonsex chromosomes (autosomes) and 2 sex chromosomes.

Each somatic cell in an individual with Down syndrome contains _ chromosomes.

47 -- Down syndrome is the result of having three copies of chromosome 21.

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 --- Mitosis follows the S phase, during which the cell's DNA is duplicated

Which of the following is a key difference between meiosis and mitosis?

Synapsis occurs

You are a medical student and are reviewing a case study about a past patient. The patient was 4 feet 8 inches tall at age 38, was unable to have children, and had an above-average intelligence. The patient also had an irregular number of chromosomes. What diagnosis would you give the patient?

Turner syndrome

Which of the following indicates Turner syndrome?

XO --- This is the sex chromosome complement of an individual with Turner syndrome.

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

cytokinesis

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

formation of a cell plate