A geneticist from an alien planet that prohibits genetic research brought with him to Earth two pure-breeding lines of frogs. One line croaks by uttering 'rib-it rib-it' and has purple eyes. The other line croaks more softly by muttering 'knee-deep knee-deep' and has green eyes. With a newfound freedom of inquiry, the geneticist mated the two types of frogs, producing F₁ frogs that were all utterers and had blue eyes. A large F₂ generation then yielded the following ratios: 27/64 blue-eyed, 'rib-it' utterer 12/64 green-eyed, 'rib-it' utterer 9/64 blue-eyed, 'knee-deep' mutterer 9/64 purple-eyed, 'rib-it' utterer 4/64 green-eyed, 'knee-deep' mutterer 3/64 purple-eyed, 'knee-deep' mutterer After years of experiments, the geneticist isolated pure-breeding strains of all six F₂ phenotypes. Indicate the F₁ and F₂ phenotypic ratios of the following cross using these pure-breeding strains: blue-eyed, 'knee-deep' 'rib-it' utterer.

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. This framework helps predict the phenotypic ratios of offspring from specific parental crosses, which is essential for analyzing the genetic outcomes in the given question.

Phenotypic Ratios

Phenotypic ratios represent the relative frequencies of different observable traits (phenotypes) in the offspring resulting from a genetic cross. In the context of the question, the F₂ generation's phenotypic ratios provide insight into the inheritance patterns of traits such as eye color and croaking sounds. Understanding these ratios is crucial for predicting the outcomes of further crosses involving the identified pure-breeding strains.

Pure-Breeding Lines

Pure-breeding lines consist of organisms that consistently produce offspring with the same phenotype when mated together. These lines are homozygous for specific traits, meaning they carry identical alleles. In the scenario presented, the geneticist's isolation of pure-breeding strains for each F₂ phenotype allows for controlled crosses to determine the inheritance patterns of traits, which is vital for answering the question about the F₁ and F₂ ratios.