Bio ch.8 pt 3 my lab

the chromosomal changes in cancer are usually confined to somatic cells

Cancer is not usually inherited because...?

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?

inversion

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

A normal watermelon has 22 chromosomes but seedless watermelons have 33 chromosomes

Polyploidy is involved in which of the following examples?

only one copy of the X chromosome is functional within any given cell, regardless of the total number of X chromosomes

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?

XO

Which of the following indicates Turner syndrome?

extra copies of the other somatic chromosomes are probably fatal

Why are individuals with an extra chromosome 21, which causes down syndrome, more numerous than individuals with an extra chromosome 3 or chromosome 16?

In trisomy there would be one extra chromosome, in a duplication, the number of chromosomes would be normal, but one chromosome would have two copies of a portion of the chromosome.

You suspect that a serious developmental disorder is due to a chromosome abnormality and prepare a karyotype from an affected individual. In analyzing the karyotype, how could you distinguish trisomy from a chromosome structural defect such as a duplication?

Karyotyping

can reveal alterations in chromosome number

Nondisjunction

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

3%

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

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___?