Question

In cats, females usually have two X chromosomes, and males usually have one X and one Y chromosome. In cats, black fur color is caused by an X-linked allele; the other allele at this locus causes orange color. The heterozygote is tortoiseshell. What kinds of offspring would you most commonly expect from the cross of an XX black female and an XY orange male? In cats, females usually have two X chromosomes, and males usually have one X and one Y chromosome. In cats, black fur color is caused by an X-linked allele; the other allele at this locus causes orange color. The heterozygote is tortoiseshell. What kinds of offspring would you most commonly expect from the cross of an XX black female and an XY orange male?

a. tortoiseshell females.
b. tortoiseshell males tortoiseshell females.
c. black males orange females.
d. orange males black females.
e. orange males orange females.
f. black males

Answer 1

a and f (Tortoise shell females and black males).

Step-by-step explanation:

Let black fur colour allele be AA, orange will be aa and tortoiseshell will be Aa. Since the trait is X-linked;

• Black female will be
  `X^(A) X^(A)`
• Orange male will be
  `X^(a)Y` (Y chromosome is assumed to not carry any trait, hence, the male can either be black or orange, they can never be heterozygote)

Crossing

`X^(A) X^(A)` x
`X^(a)Y`

Progeny:
`X^(A)X^(a)`,
`X^(A)X^(a)`,
`X^(A)Y`,
`X^(A)Y`

• Two heterozygote/tortoiseshell fur colour females
• Two black males

The correct answer is a and f.