A male rabbit that is homozygous recessive for hair and color is crossed with heterozygous female rabbit.
With four by four square.
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 (male) X RrBb (female)
Phenotypic ratio:
To determine the phenotypic ratio, we need to look at the different combinations of alleles the offspring can inherit for hair and color.
Hair:
- rr (short hair) from the male parent
- Rr (short hair) or Rr (short hair) or RR (long hair) from the female parent
Color:
- bb (black color) from the male parent
- Bb (black color) or Bb (black color) or BB (white color) from the female parent
Combining the possibilities:
- rrbb (short black hair)
- Rrbb (short black hair)
- rrBb (short black hair)
- RrBb (short black hair)
- RRbb (long black hair)
- RRbb (long black hair)
- RRbb (long black hair)
- RRbb (long black hair)
- rrBB (short white hair)
- RrBB (short white hair)
- rrBB (short white hair)
- RrBB (short white hair)
- RRBB (long white hair)
- RRBB (long white hair)
- RRBB (long white hair)
- RRBB (long white hair)
Counting the different possibilities, we get:
- 4 offspring with short black hair (rrbb)
- 4 offspring with short white hair (rrBB or RrBB)
- 4 offspring with long black hair (RRbb)
- 4 offspring with long white hair (RRBB)
Therefore, the phenotypic ratio is 4:4:4:4.
Percent probability of offspring with short, black hair:
Counting only the offspring with short black hair (rrbb), we have 4 possibilities out of a total of 16 possibilities. So the percent probability is (4/16) * 100 = 25%.
Percent probability of offspring with long, white hair:
Counting only the offspring with long white hair (RRBB), we have 4 possibilities out of a total of 16 possibilities. So the percent probability is (4/16) * 100 = 25%.