Question

In ferrets, fur color is controlled by a single gene and there are two phenotypes: brown fur and grey fur. You cross a pure-breeding brown ferret to a pure-breeding grey ferret and all the progeny are brown. You then find a brown ferret of unknown genotype and cross it to a grey ferret. In the F1 of this second cross you observe a 1:1 phenotype ratio of brown-to-grey progeny. What are the most likely genotypes of the parents in this second cross?

Answer 1

Answer:

The parents in this second cross will have genotype "Bb" and  "bb"

Explanation:

Given -

There are two alleles for fur coat.

Let "B" represents the brown fur color and

"b" represents the grey fur color

Genotype of a pure-breeding brown ferret is "BB"

Genotype of a pure-breeding grey ferret is "bb"

When BB is crossed with bb, all offspring will have genotype "Bb"

Since brown is dominant over grey fur color, hence all offspring with genotype "Bb" will have brown color.

Now this "Bb" offspring is crossed with grey ferret with genotype "bb"

The offspring produced when Bb is crossed with bb

Bb X bb

Bb, Bb, bb, bb

Brown :Grey

$2:2\\1:1$

The parents in this second cross will have genotype "Bb" and  "bb"