Epistasis occurs when the the alleles of one gene mask the phenotypic effects of the alleles of another gene at a different locus. This phenomenon can be observed in the sweet pea, Lathyrus odoratus:
* C (one purple color producing) allele is dominant to c (white)
* P (another purple color producing) allele is dominant to p (white)
* cc or pp masks the P or C alleles, producing white color
Determine the genotypic and phenotypic ratios of a cross between a purple and white sweet pea: CcPp x ccPP