The Phenotypes in a Monohybrid Cross

Understanding Phenotypes in a Monohybrid Cross

When we talk about phenotypes in a monohybrid cross, we are referring to the observable traits or characteristics of an organism resulting from the interaction of its genetic makeup (genotype) with the environment. In a monohybrid cross, two individuals that are true-breeding for different traits are crossed to study the inheritance of a single trait.

During this cross, the F1 generation is produced, which consists of offspring that are all heterozygous for the trait in question. It is important to understand how these heterozygotes display their phenotypes in relation to their parents.

The Phenotypes of F1 Heterozygotes

Final answer:

In a monohybrid cross, the F1 heterozygotes display the dominant phenotype, which mirrors that of the homozygous dominant parent. This is indicative of the inheritance pattern of dominant and recessive alleles, where the F1 generation expresses the dominant trait.

Explanation:

Regarding the phenotypes in a monohybrid cross, the F1 heterozygotes display the same phenotype as the homozygous dominant parent. This occurs because in inheritance patterns involving dominant and recessive alleles, the dominant phenotype is expressed in the F1 generation. The heterozygous F1 offspring result from a cross between two true-breeding, or homozygous, parents exhibiting different traits.

When these F1 heterozygotes are self-crossed to produce F2 offspring, the resultant traits show a phenotypic ratio of approximately 3:1, where three-quarters of the offspring display the dominant phenotype and one-quarter display the recessive phenotype. This is because the genotypic ratio in the F2 generation follows the pattern of one quarter homozygous dominant, one half heterozygous, and one quarter homozygous recessive, with the homozygous dominant and heterozygous individuals being phenotypically indistinguishable.