In a plant, a tall variety was crossed with a dwarf variety. All F₁ plants were tall. When F₁xF₁ plants were interbred, 9/16 of the F₂ were tall and 7/16 were dwarf. What proportion of the F₂ plants will be true breeding if self-fertilized? List these genotypes.

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 traits mask the expression of recessive ones. In this case, the tall variety is dominant over the dwarf variety, leading to all F₁ plants being tall.

Genotype and Phenotype

The genotype refers to the genetic makeup of an organism, while the phenotype is the observable physical or biochemical characteristics. In the given scenario, the F₁ plants are heterozygous (Tt), resulting in a tall phenotype. The F₂ generation's phenotypic ratio of 9:7 indicates the presence of both homozygous dominant (TT) and heterozygous (Tt) genotypes contributing to the tall phenotype.

True Breeding

True breeding refers to organisms that, when self-fertilized, produce offspring with the same phenotype and genotype. In this context, true breeding tall plants would be homozygous dominant (TT), while true breeding dwarf plants would be homozygous recessive (tt). The proportion of true breeding plants in the F₂ generation can be calculated from the genotypic ratio derived from the Punnett square analysis of the F₁ cross.