A male rabbit that is heterozygous for both traits is crossed with a female rabbit that is
heterozygous for both traits.
Parent genotypes: ____________ X ____________
Parent genotypes: RrYy X RrYy
What is the phenotypic ratio? ______________________ ● What is the percent probability that the offspring will have short, black hair? ______________ ● What is the percent probability that the offspring will have long, white hair? ______________
The phenotypic ratio can be determined by using the Punnett square.
Punnett square:
R r
Y RRYy RrYy
y RRYy RrYy
From the Punnett square, we can see that the possible genotypes and their corresponding phenotypes are:
- 9 offspring with black, short hair (RRYY, RRYy, RRyy, RrYY, RrYy, Rryy)
- 3 offspring with black, long hair (RRYY, RRYy, RrYY)
- 3 offspring with white, short hair (RRyy, RrYy, Rryy)
- 1 offspring with white, long hair (rryy)
So, the phenotypic ratio is:
9 black, short hair : 3 black, long hair : 3 white, short hair : 1 white, long hair
which can be simplified to:
9:3:3:1
To calculate the percent probability, we add up the offspring with short, black hair and divide it by the total number of offspring multiplied by 100:
Percent probability of offspring with short, black hair:
(9 / 16) x 100 = 56.25%
Percent probability of offspring with long, white hair:
(1 / 16) x 100 = 6.25%