Question

In dogs, the color black is dominant to white and follows the rules of simple Mendelian inheritance. What would be the phenotype ratio of a heterozygous black dog was crossed with a white dog?

Answer 1

If the color black is dominant to white, then black is a dominant trait and white is  a recessive trait. If the genotype of a pure black dog is BB, then the genotype of a white dog is bb, and the genotype of a heterozygous black dog is Bb. Using Punnett square, the results of a heterozygous black dog crossed with a white dog is Bb, Bb, bb, bb. So, the phenotype ratio is 2:2 or 1:1.