Chapter 10
Sickle-cell anemia is an inherited chronic blood disease caused by an autosomal recessive allele. Suppose a man who is homozygous recessive for the sickle-cell gene fathers a child by a woman who is a carrier for sickle-cell. What are the chances their children will exhibit the disease? (Note: A Punnett square may be useful.)
50%
All humans are capable of producing gametes containing different sex chromosomes.
False
Males with a recessive X-linked allele that causes a disorder do not always show symptoms because they can also carry a dominant allele on their Y chromosome.
False
Which of the following statements about crossing-over is true?
It disrupts the linkage between genes.
Sex-linked genes are found on either the X chromosome or the Y chromosome but not both.
True
Down syndrome in humans is an example of
a change in the overall number of chromosomes.
Which of the following genetic changes would not be heritable?
a mutation in a skin cell
Most inherited human disorders are the result of
recessive mutations of genes located on autosomes.
The probability that two genes will be separated by crossing-over is related to:
the distance between the two genes on the chromosome.
On chromosomes, a pair of linked genes will be found only on
the same chromosome