In chickens, the striped plumage gene is located on the X chromosome and is dominant.

In chickens, the striped plumage gene is located on the X chromosome and is dominant. The recessive allele is black. Y does not carry this kind of information. Which rooster and which hen should be crossed to make black hens and striped roosters?

To solve the problem, it should be remembered that homozygosity is a prerequisite under which a recessive trait acquires the ability to be realized in a phenotype.

Striped cockerels, according to the condition of the problem, will be the owners of the ХВХ? Genotype. Black chickens – XbY.

In order for all hens to be black in the offspring, the male must produce only germ cells with the recessive trait Xb, which will manifest itself in 100% of cases of the absence of a parallel gene in combination with Y. Therefore, his genotype will look like this: XbXb. Such a cock will be black.

In order for all males in the offspring to be striped, provided that they are homozygous for the recessive gene of the rooster father, the mother hen must carry the dominant gene in her only X chromosome, and her genotype will look like this: XBY. Such a chicken will be striped.