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Biology quiz 8

Which of the following statements about nondisjunction is false?

In mammals, extra copies of the Y chromosome are typically inactivated.

Which of the following statements regarding the function of mitosis is false?

Mitosis allows organisms to generate genetic diversity.

Eukaryotic chromosomes differ from prokaryotic chromosomes in that they

are housed in a membrane-enclosed nucleus.

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

cytokinesis.

The phase of mitosis during which the nuclear envelope fragments and the nucleoli disappear is called

prophase

You are asked to culture an unidentified sample of animal tissue. You notice that the cells seem to fail to exhibit density-dependent inhibition. The source of this tissue sample is most likely

a cancer.

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.

Cancer is not usually inherited because

the chromosomal changes in cancer are usually confined to somatic cells

If the S phase were eliminated from the cell cycle, the daughter cells would

have half the genetic material found in the parent cell.

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

metaphase

At the start of mitotic anaphase,

the centromeres of each chromosome come apart.

Which of the following is probably the main factor responsible for the phenomenon of density-dependent inhibition?

availability of growth factors

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

does not metastasize.

Mature human nerve cells and muscle cells

are permanently in a state of nondivision.

Karyotyping

can reveal alterations in chromosome number.

Which of the following statements regarding Down syndrome is false?

Women with Down syndrome cannot reproduce.

If a chromosome fragment breaks off and then reattaches to the original chromosome, but in the reverse direction, the resulting chromosomal abnormality is called a(n)

inversion.

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

telophase

During which stage of meiosis does synapsis and the formation of tetrads occur?

prophase I

If these four cells resulted from cell division of a single cell with diploid chromosome number 2n = 4, what best describes what just occurred?

meiosis with nondisjunction in meiosis II

Which of the following features likely accounts for the difference between plant and animal cell cytokinesis?

Plant cell division must maintain the integrity of the cell wall.

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.

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.

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

possible combinations of characteristics.

After reading the following paragraph, answer the question(s) below.
Mr. and Mrs. Smith have three sons in elementary school. Two of their children are progressing normally, but their last son, Charles, has been much slower than his siblings at developing speech and language skills. His parents are concerned that he has a learning disability and decide to investigate further. Since some learning disabilities can be genetically based, their pediatrician recommends a chromosomal analysis.
The results show that Charles has a trisomy of the sex chromosomes, diagnosed as XYY, which is caused by nondisjunction in the formation of the father's sperm. The nondisjunction resulted in an extra copy of the Y chromosome. The extra copy was passed on to Charles during fertilization. Most often, this chromosomal change causes no unusual physical features or medical problems, but those with trisomy of the sex chromosomes do have a higher than normal risk of delays in learning development.
During which stage of meiosis must this nondisjunction have occurred?

metaphase II

Which of the following occurs during interphase?

cell growth and duplication of the chromosomes

Sister chromatids are

tightly linked together at a centromere.

After reading the following paragraph, answer the question(s) below.
Mr. and Mrs. Smith have three sons in elementary school. Two of their children are progressing normally, but their last son, Charles, has been much slower than his siblings at developing speech and language skills. His parents are concerned that he has a learning disability and decide to investigate further. Since some learning disabilities can be genetically based, their pediatrician recommends a chromosomal analysis.
The results show that Charles has a trisomy of the sex chromosomes, diagnosed as XYY, which is caused by nondisjunction in the formation of the father's sperm. The nondisjunction resulted in an extra copy of the Y chromosome. The extra copy was passed on to Charles during fertilization. Most often, this chromosomal change causes no unusual physical features or medical problems, but those with trisomy of the sex chromosomes do have a higher than normal risk of delays in learning development.
If Charles gets married and starts a family, which of the following chromosomal abnormalities might be found in his children?

XXY

Which of the following types of organisms commonly demonstrates polyploidy?

flowering plants

Nondisjunction occurs when

members of a chromosome pair fail to separate.

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