In peas, purple flowers are dominant to white. If a purple-flowered, heterozygous plant were crossed with a white-flowered plant, what is the expected ratio of genotypes and phenotypes among the F1 offspring? If two of the purple-flowered F1 offspring were randomly selected and crossed, what is the expected ratio of genotypes and phenotypes among the F2 offspring?

Key Concepts

Mendelian Genetics

Mendelian genetics is the study of how traits are inherited through generations, based on the principles established by Gregor Mendel. It involves understanding dominant and recessive alleles, where dominant alleles mask the expression of recessive ones. In this case, the purple flower trait is dominant over the white flower trait in peas.

Punnett Square

A Punnett square is a diagram used to predict the genotypes and phenotypes of offspring from a genetic cross. It organizes the possible combinations of alleles from the parents, allowing for easy visualization of the expected ratios. For the cross between a heterozygous purple-flowered plant and a white-flowered plant, the Punnett square helps determine the expected ratios of the F1 generation.

Genotype and Phenotype Ratios

Genotype refers to the genetic makeup of an organism, while phenotype refers to the observable traits. In the context of the F1 and F2 generations, the expected genotype and phenotype ratios can be calculated based on the alleles inherited. For example, the F1 generation from the initial cross will show a specific ratio of purple to white flowers, while the F2 generation will exhibit a different ratio due to the combination of alleles from the F1 offspring.