Question

In guinea pigs, the allele for black fur (B) is dominant over the allele for white fur (b). A black male guinea pig is mated to a white female guinea pig. The offspring were 7 black and 6 white guinea pigs. What are the genotypes of the parents?

Answer 1

Answer:

Male: Bb

Female: bb

Explanation:

1. I made punnet squares to test each genotype pairs:

BB (black male) x bb (white female)

Bb (black male) x bb (white female)

** B is dominant over b so if Bb, black will be expressed

3. I calculated the percentage of each phenotype to see if it matched the the number of white and black guinea pigs produced. I found that Bb x bb had 50% chance for white guinea pigs and 50% chance for black guinea pigs, which is about the same in the scenario above (7 black, 6 white).

4. I infered that the male black guinea pig's genotype is Bb and the female white guinea pig's genotype is bb.