Biology quiz 8.18-8.23

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

Which of the following statements about nondisjunction is false? In mammals, extra copies of the Y chromosome are typically inactivated. Women with a single X chromosome have Turner syndrome and are sterile. Nondisjunction in meiosis can affect autosomes and sex chromosomes. In general, a single Y chromosome is enough to produce "maleness."

can reveal alterations in chromosome number.

Karyotyping _____________________________________________________________.

Down syndrome is caused by a trisomy of chromosome 21. The incidence of Down syndrome in infants born to mothers under the age of 35 is less than 0.5%. The risk of having a baby with Down syndrome more than doubles for 45-year old mothers compared to 40-year old mothers.

Use the graph and your knowledge of Down syndrome to select the three true statements. The number of infants born with Down syndrome increases at a steady rate from maternal age 25 to 50. Down syndrome is caused by a trisomy of chromosome 21. The incidence of Down syndrome in infants born to mothers under the age of 35 is less than 0.5%. The risk of having a baby with Down syndrome more than doubles for 45-year old mothers compared to 40-year old mothers. The largest five-year increase in the incidence of Down syndrome occurs between the maternal ages of 35 and 40.

photographs of every couple at a high school prom.

A karyotype is most like...

the chromosomal changes in cancer are usually confined to somatic cells.

Cancer is not usually inherited because

1

How many generations does it take to develop a new plant species by polyploidy?

inversion

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)

nondisjunction

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

Anaphase II

Mr. and Mrs. Smith have three sons in elementary school. Two of their children are progressing normally, but their youngest son, Charles, has been much slower than his siblings in 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 could this nondisjunction have occurred?

XXY

Mr. and Mrs. Smith have three sons in elementary school. Two of their children are progressing normally, but their youngest son, Charles, has been much slower than his siblings in 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 has an increased chance of occurring in his children?

3%

On average, what percentage of infants born to 45-year-old mothers have Down syndrome?

Down syndrome is least likely to be seen in the infants of mothers over 40.

Which of the following statements regarding Down syndrome is false? Down syndrome is least likely to be seen in the infants of mothers over 40. Down syndrome is the most common serious birth defect in the United States. Trisomy 21 is the cause of Down syndrome. People with Down syndrome usually have a shorter life span than normal.

flowering plants

Which of the following types of organisms commonly demonstrates polyploidy?

Where is cat?

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

Turner syndrome

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?