Mendel crossed peas having green seeds with peas having yellow seeds. The F₁ generation produced only yellow seeds. In the F₂, the progeny consisted of 6022 plants with yellow seeds and 2001 plants with green seeds. Of the F₂ yellow-seeded plants, 519 were self-fertilized with the following results: 166 bred true for yellow and 353 produced an F₃ ratio of 3/4 yellow: 1/4 green. Explain these results by diagramming the crosses.

Key Concepts

Mendelian Inheritance

Mendelian inheritance refers to the principles of heredity established by Gregor Mendel through his experiments with pea plants. He discovered that traits are inherited in discrete units, now known as genes, and that these traits segregate independently during gamete formation. This concept is foundational for understanding dominant and recessive traits, where dominant traits mask the expression of recessive ones in heterozygous individuals.

Phenotypic Ratios

Phenotypic ratios describe the relative frequencies of different phenotypes in the offspring resulting from a genetic cross. In Mendel's experiments, the F₂ generation exhibited a typical 3:1 ratio of dominant to recessive traits when self-fertilizing heterozygous individuals. This ratio helps predict the expected distribution of traits based on the genotypes of the parents and is crucial for analyzing the results of genetic crosses.

Self-Fertilization and True Breeding

Self-fertilization occurs when a plant's pollen fertilizes its own ovules, leading to offspring that are genetically similar to the parent. True breeding refers to organisms that consistently produce offspring with a specific phenotype when self-fertilized. In the context of the F₂ generation, the results of self-fertilization of yellow-seeded plants demonstrate the segregation of alleles and the potential for both yellow and green seeds to appear in subsequent generations.