Final answer:
The parent plants of four o'clocks with 50% white and 50% pink offspring likely have heterozygous genotypes, represented as 'Pw', where 'P' signifies the allele for the pink color and 'w' for white. This suggests incomplete dominance, where the heterozygous genotype leads to a blended pink phenotype.
Step-by-step explanation:
The student's question relates to a classic genetics problem, which can be illuminated by Gregor Mendel's experiments with pea plants. In Mendel's monohybrid cross experiments, he observed that certain traits followed specific patterns of inheritance, with his most famous being the observation of purple and white flowers in pea plants. Mendel crossed true-breeding purple flower plants (with the genotype 'BB', where 'B' represents the dominant allele for purple color) with true-breeding white flower plants (with the genotype 'bb', where 'b' represents the recessive allele for white color). The F1 generation displayed all purple flowers due to the dominance of the 'B' allele. When these F1 plants were self-pollinated, the resulting F2 generation had a phenotypic ratio of approximately 3:1, with 75% displaying purple flowers and 25% displaying white flowers.
In the scenario described by the student, Matthew planted four o'clocks, and the seeds came from one set of parents, resulting in 50% white and 50% pink flowers. This implies that pink is a result of incomplete dominance, where neither allele is completely dominant over the other, resulting in a blend of parental traits.
Therefore, the parent plants would both have to be heterozygous (having one of each allele), which we can represent as 'Pw' where 'P' is the allele for pink and 'w' is the allele for white. When these heterozygous plants are crossed (Pw x Pw), the expected phenotypic outcome would be 25% 'PP' (pink), 50% 'Pw' (also pink due to incomplete dominance), and 25% 'ww' (white). However, in this specific question, if the student only observes pink and white flowers at a 1:1 ratio, it's possible that 'pink' and 'white' are the only visible phenotypes due to the incomplete dominance phenomena, with the 'PP' classification also displaying as pink.