Three independently assorting genes (A, B, and C) are known to control the following biochemical pathway that provides the basis for flower color in a hypothetical plant: Three homozygous recessive mutations are also known, each of which interrupts a different one of these steps. Determine the phenotypic results in the F₁ and F₂ generations resulting from the P₁ crosses of true-breeding plants listed here: yellow (AAbbCC) × green (AABBcc)

Key Concepts

Independent Assortment

Independent assortment is a fundamental principle of genetics that states genes for different traits segregate independently of one another during gamete formation. This means that the inheritance of one trait will not affect the inheritance of another, allowing for a variety of combinations in offspring. In the context of the question, it implies that the alleles for genes A, B, and C will assort independently when determining the phenotypes of the F₁ and F₂ generations.

Homozygous and Heterozygous Genotypes

A homozygous genotype consists of two identical alleles for a particular gene, while a heterozygous genotype contains two different alleles. In the given question, the parental plants are homozygous for their respective traits (AAbbCC and AABBcc), which will influence the genotypic and phenotypic ratios in the offspring. Understanding these terms is crucial for predicting the genetic outcomes in the F₁ and F₂ generations.

Phenotypic Ratios

Phenotypic ratios refer to the relative frequencies of different phenotypes in the offspring resulting from a genetic cross. In this scenario, the phenotypic results in the F₁ and F₂ generations can be calculated based on the combinations of alleles inherited from the parents. Analyzing these ratios helps in understanding how the recessive mutations affect flower color and how they manifest in the offspring's traits.