Determine the genotype of the purple flower if (p) is dominant and white (p) is recessive

If the genotype is PP then when crossed with pp all the offspring will be Pp and purple. 
If the genotype is Pp then when crossed with pp 50% of the offspring wil be Pp (purple) and 50 % will be pp (white). 
These results will allow you to see whether the purple is homozygous (PP) or heterozygous (Pp).

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