Question

In Labrador Retrievers, the allele for a black coat color (B) is dominant over the allele for a brown coat color (b). If a brown Labrador Retriever is crossed with a heterozygous black Labrador Retriever, which of the following genotypic ratios can be expected?

a) 1 BB : 2 Bb : 1 bb

b) 1 BB : 1 Bb : 2 bb

c) 2 BB : 2 Bb : 0 bb

d) 0 BB : 1 Bb : 1 bb

Answer 1

The genotypic ratios can be expected to be 1 BB : 1 Bb : 2 bb.

Step-by-step explanation:

To determine the genotypic ratios, we need to use a Punnett square. In this case, we have a brown Labrador Retriever (bb) crossed with a heterozygous black Labrador Retriever (Bb). The Punnett square for this cross would be as follows:

BbbBbbb

The genotypic ratios are 1 Bb : 1 bb, so the correct answer is b) 1 BB : 1 Bb : 2 bb.