Question

A yellow cat is crossed with a black cat. You know that the black and yellow fur color traits are carried on the X chromosome and only one X chromosome is expressed in a cell. You observe that half the offspring are calico (patches of black and yellow) and half are black. Your friend Tien tells you that the black cat was the mother, the yellow cat was the father, and all the calico kittens are females. Is he correct? Write out all the possible crosses to test his answer.

Answer 1

Answer:

Tien is correct with his answer that all the calico kittens are females.

The reason and the possible crosses to test the answer are given below

Explanation:

First of all, the coat color in cats is hugely decided by the sex-linked  X chromosome in the female. This X chromosome found in cats makes cats exhibit codominant traits. The calico cat is a blend of black and yellow patches. To be considered calico, a cat must carry an allele for the black color and an allele for the yellow color.

The male is no heterozygotes and since the Y- chromosome in the male doesn't affect the result of the coat color in the offspring, there has to be a rare genetic disorder that will result in a calico kitten that is male.

The possible crosses to test his answer:

Cross 1:

If the black cat was the mother her genotype would be: Xb Xb

If the yellow cat was the father his genotype would be: Xy Y

The possible offspring from the cross would result in:

XbXy XbY XbY XbXy ( where XbXy are calico females and XbY are black males)

Cross 2:

If the yellow cat was the mother her genotype would be: Xy Xy

If the black cat was the father his genotype would be: Xb Y

The possible offspring from the cross would result in:

XyXb  XyY XyXb XyY (where XbXy are calico females and XyY are the yellow males)