Answer to Question #64961 in Biology for DD

Question

Black and white coloration in cows is dominant to brown and white. Black and white cows were crossed over several years and the following progeny were produced: 8 black and white and 3 brown and white. What is the most probable genotype of each parent?

What is the expected genotypic and phenotypic ratio expected for the progeny in the previous question?

Answer 1

Let B denote black and white color, and b denote brown and white color
Genotypes corresponding to black and white color are BB and Bb
Genotype corresponding to brown and white color is bb
As brown and white offspring were produced, both parents with black and white color must have the recessive allele
Thus, both parents have genotypes Bb.

So, the cross was the following:

P: Bb Bb
G: B and b B and b
F1: BB Bb Bb bb

The expected phenotypic ratio is 3 black and white : 1 brown and white
The genotypic ratio is 1 BB: 2 Bb: bb