In horses, the allele for a black coat (B) is dominant over the allele for a brown coat (b). A cross between a black horse and a brown horse produces a brown foal. Is the black horse a homozygous or heterozygous for coat color? BB x bb or Bb x bb

Question

Maverick Raymond

Biology

29 June, 18:44

In horses, the allele for a black coat (B) is dominant over the allele for a brown coat (b). A cross between a black horse and a brown horse produces a brown foal. Is the black horse a homozygous or heterozygous for coat color? BB x bb or Bb x bb

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Answers (1)

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Gloria Harper · Answer 1

Bb X bb

Explanation:

It is given that the allele B for the black coat is dominant over allele b for a brown coat. A dominant allele always leads to the expression of the dominant trait in the heterozygous condition. When a black and brown horse is crossed as given in the question and the result is a brown foal, then the genotype of the brown foal must be bb as the brown coat is a recessive trait. Since each parent contributes one allele each for a given gene, the black horse must have b allele, and hence must be heterozygous Bb. The cross is shown in the punnett square.