| F1: AaBb X AaBb | |||
| ↓ | |||
| F2 ratio | Genotype | Phenotype | Final Phenotypic ratio |
|---|---|---|---|
| 9/16 | A- B- | white |
12/16 white 3/16 yellow 1/16 green |
| 3/16 | A- bb | white | |
| 3/16 | aa B- | yellow | |
| 1/16 | aa bb | green | |
The dominant allele A results in white fruit color of the summer squash
regardless of the genotype at a second locus, B.
In the absence of a dominant A allele (the aa genotype),
BB or Bb results in yellow color,
while bb results in green color.
Crossing two white-colored double heterozygotes (AaBb) produces a
phenotypic ratio of 12:3:1.