A pea plant with purple flowers (and unknown genotype) is crossed with a pea plant with white flowers. one-half of the offspring have purple flowers and one-half have white flowers. what are the genotypes of the parent plants? see section 11.3 (page 177).

The genotypes of the parents are Aa (heterozygous) and aa (recessive homozygous).

For example:

If the purple flower is dominant phenotype, then A is a dominant allele for it and Aa is a genotype which will give the purple colour.

In this case, white flower is recessive phenotype with aa genotype.

If we cross Aa x aa

The offspring is going to be Aa Aa aa aa (half purple and half white)