Sex-Linked II.

Which chromosome contains more genes?

• The X chromosome

• The Y chromosome

• They are homologous, so they contain the same amount of genes.

Males can be heterozygous for sex-linked traits.

• True

• False

What would the genotype be of a colorblind male?

• X^NY

• X^NYⁿ

• XⁿY

• XⁿYⁿ

How many recessive genes does a carrier female have for colorblindness?

• 1

• 2

• 0

Colorblindness is a sex-linked recessive trait. A colorblind woman marries a male with normal color vision. What is the percent chance of them having a color blind son?

• 0%

• 25%

• 50%

• 75%

Muscular dystrophy is a sex-linked recessive disorder. A man with muscular dystrophy marries a woman who doesn’t have this disease. Half of their daughters and half of their sons develop this disease. What is the genotype of the mother?

• X^NX^N

• X^NXⁿ

• Xⁿ

• X^N

A boy whose parents have normal vision is colorblind. What are the genotypes for his mother and father? Use X^N for normal vision and Xⁿ for colorblindness. Show the Punnett square to support your answer.

• X^bY

• X^BY

• X^BX^B

• X^BX^b

• X^bX^b

The bison herd on Konza Prairie has a sex-linked trait known as “rabbit hock” in which the knee of the back leg is slightly malformed. A male bull that is normal mates with a cow that is a carrier for rabbit hock. Of the female offspring, what percent would be carriers?

• 0%

• 25%

• 50%

• 100%

A woman who is colorblind has a mother with normal vision. Knowing that colorblindness is a sex-linked recessive gene, what is her mother’s genotype? What is her father’s genotype? Use X^N for normal vision and Xⁿ for colorblindness.

• X^NX^N

• XⁿY

• X^NXⁿ

• XⁿXⁿ

• X^NY

The woman who is colorblind marries a man with normal vision. What is the probability that their sons will be colorblind?

• 0%

• 25%

• 50%

• 100%