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full X shrunken

Purple X yellow produces approximately 1/2 purple and 1/2 yellow. A 1:1 ratio is usually caused by a cross between a heterozygote and a homozygote. Because purple is dominant, the purple parent must be heterozygous (Pp) and the yellow parent must be homozygous (pp). The purple progeny produced by this cross will be heterozygous (Pp) and the yellow progeny must be homozygous (pp).

Now let's examine the other character. Full X shrunken produces 1/2 full and 1/2 shrunken, or a 1:1 ratio, and so these progeny phenotypes also are produced by a cross between a heterozygote (Ff) and a homozygote (ff); the full-kernel progeny will be heterozygous (Ff) and the shrunken-kernel progeny will be homozygous (ff).

Now combine the two crosses and use the multiplication rule to obtain the overall genotypes and the proportions of each genotype:

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