"Plants from two pure lines", one with purple flowers (P/P) and the other with white flowers (p/p), are crossed. The resulting F1 generation has only purple flowers. When these F1 plants are selfed, what is the ratio of flower color genotypes in the progeny?

3/4 purple : 1/4 white

Explanation:

The pure breeding parent plants have genotype PP and pp. The plant with the "PP" genotype will make all the gametes with the "P" allele while the plant with "pp" genotype will make all the gametes with the "p" allele. The random fusion of these gametes produces F1 progeny with the "Pp" genotype and purple phenotype. A cross between two F1 plants (Pp x Pp) produce progeny in the following phenotype ratio=

Pp x Pp = 3/4 purple : 1/4 white

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explanation: