In garden peas, one pair of alleles controls the height of the plant, and a second pair of alleles controls flower color. The allele for tall (D) is dominant to the allele for dwarf (d), and the allele for purple (P) is dominant to the allele for white (p). A tall plant with white flowers crossed with a dwarf plant with purple flowers produces 1/4 tall purple, 1/4 tall white, 1/4 dwarf purple, and 1/4 dwarf white. What is the genotype of the parents

This question involves two different genes coding for height and flower color in pea plants. The alleles for tallness (D) and purple color (P) are dominant over the alleles for dwarfness (d) and white color (p) respectively.

According to this question, a tall plant with white flowers is crossed with a dwarf plant with purple flowers to produce the following proportion of offsprings: 1/4 tall purple, 1/4 tall white, 1/4 dwarf purple, and 1/4 dwarf white.

Since some of the offsprings contain recessive alleles for both or either genes, the dominant traits of the parent is controlled by an heterozygous genotype. This means that the tall plant with white flowers has a genotype: Ddpp while the dwarf plant with purple flowers has the genotype: ddPp. In a cross between Ddpp × ddPp, 1/4 of each combination of alleles is produced in the offsprings (see punnet square in the attachment).