A male rabbit that is heterozygous for both traits is crossed with a female rabbit that is
heterozygous for both traits.
Parent genotypes: ____________ X ____________
● 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? ______________
Parent genotypes: RrBb X RrBb (R represents the dominant gene for short hair, r represents the recessive gene for long hair; B represents the dominant gene for black hair, b represents the recessive gene for white hair)
Phenotypic ratio: The phenotypic ratio can be determined by using the Punnett square method. Each parent has 4 possible gametes (RB, Rb, rB, rb). When the gametes are crossed, the possible genotypes of the offspring are RRBB, RRBb, RRbb, RrBB, RrBb, Rrbb, rrBB, rrBb, rrbb.
The phenotypic ratio is therefore:
- 9/16 will have short, black hair
- 3/16 will have short, white hair
- 3/16 will have long, black hair
- 1/16 will have long, white hair
The phenotypic ratio is 9:3:3:1.
Percent probability of offspring having short, black hair: (9/16) x 100 = 56.25%
Percent probability of offspring having long, white hair: (1/16) x 100 = 6.25%