Question

In Labrador Retrievers, black fur is dominant to yellow fur. How is it possible that 2 retrievers with black fur reproduce puppies with yellow fur

Answer 1

Answer:  Two Labrador retrievers with black fur can reproduce puppies with yellow fur only when their genotypes are heterozygous dominant for black fur that is- Bb and Bb.

Exaplanation-

As per the given information in the question, black fur is dominant (B) to yellow fur (b). A dominant trait ( depicted by capital letter) masks the expression of recessive trait.

There can be two possible genotypes for black fur that is BB ( homozygous dominant) and Bb ( heterozygous dominant) whereas yellow fur ( which is a recessive trait) can only have one genotype that  bb ( homozygous recessive).

When 2 Labrador retrievers with heterozygous dominant genotype ( Bb) are crossed, they is 25% chance of producing a puppy with yellow fur ( bb).

Refer punnett square.