In cattle, hornlessness dominates over horniness, and coloration is controlled by a pair of genes with incomplete dominance

In cattle, hornlessness dominates over horniness, and coloration is controlled by a pair of genes with incomplete dominance – homozygous animals have a red or white color, and heterozygous animals have a roan. A hornless roan bull, when crossed with a horned white cow, gave a horned roan heifer. What are the genotypes of all these animals?

Let the gene that determines the hornlessness of cattle be B, then the gene that determines the development of horns will be b.

Let the gene for the red suit of cattle be C, the gene for the white suit – with, then the genotype of roan cows will be Cc.

Let’s start with the horned roan heifer: its genotype will be bbCc, because homozygosity for the recessive horniness gene is an indispensable condition for the phenotypic realization of this trait, and the combination of genes that determines the roan color in the phenotype is known by the condition of the problem.

The horned white cow will be bbcc, due to the recessiveness of the traits manifested in its phenotype. She produces the same type of eggs bc.

To have a horned heifer in the offspring, a hornless bull must carry the recessive gene for hornlessness in a latent form as part of its genotype. Therefore, he is BbCc.

Answer: cow – bbccc, bull – BbCc, heifer – bbCc.