Final answer:
The possible phenotypes for the offspring of two heterozygous purple flower parents (Pp x Pp) are purple and white flowers. Using a Punnett square, the expected phenotypic ratio is 3 purple to 1 white, meaning 75% have purple flowers and 25% have white.
Step-by-step explanation:
When two heterozygous parents with purple flowers are crossed, the possible phenotypes of their offspring can be determined using a Punnett square. Since purple flowers are dominant (P) over white (p) and each parent is heterozygous (Pp), the potential genotypes of the offspring are PP, Pp, and pp. The phenotype for PP and Pp will be purple flowers, as the dominant allele P expresses the purple color. However, the phenotype for pp will be white flowers since there are no dominant alleles to express purple.
According to the Mendelian inheritance, the genotypic ratio for a cross between two heterozygous parents (Pp x Pp) is 1 PP : 2 Pp : 1 pp, and the phenotypic ratio is 3 purple : 1 white. This means that 75 percent of their offspring is expected to have purple flowers, and 25 percent is expected to have white flowers.