Datura stramonium (the Jimsonweed) expresses flower colors of purple and white and pod textures of smooth and spiny. The results of two crosses in which the parents were not necessarily true breeding are shown below. Assuming that true-breeding strains of all combinations of traits are available, what single cross could you execute and carry to an F₂ generation that will prove or disprove your hypothesis? Assuming your hypothesis is correct, what results of this cross will support it?

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, genotype versus phenotype, and how these factors influence the inheritance patterns observed in offspring. This framework is essential for predicting the outcomes of genetic crosses, such as those involving Datura stramonium.

Punnett Square

A Punnett square is a diagram used to predict the genotypic and phenotypic ratios of offspring from a genetic cross. By organizing the alleles of the parents, it allows for a visual representation of all possible combinations in the offspring. In the context of the question, constructing a Punnett square for the Datura stramonium traits will help determine the expected ratios of flower colors and pod textures in the F₂ generation.

Phenotypic Ratios

Phenotypic ratios represent the relative frequencies of different phenotypes in the offspring resulting from a genetic cross. These ratios are derived from the combinations of alleles and can provide evidence to support or refute a hypothesis about inheritance patterns. In the case of Datura stramonium, understanding the expected phenotypic ratios from a specific cross will be crucial for validating the proposed hypothesis regarding flower color and pod texture.