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Dihybrid Cross using Mendelian Genetics

A scientist studying diploid pea plants is interested in two particular traits of the plant: pea color and pea texture. From previous studies, the scientist knows these traits to be genetically unlinked; therefore, these traits follow the Mendelian principles of segregation and independent assortment. The scientist also knows that peas are either phenotypically green or yellow in color, with green being genotypically dominant to yellow. Peas are also either smooth or wrinkled in texture, with smooth being genotypically dominant to wrinkled. Therefore, there are four possible phenotypic combinations of these two traits in peas: green smooth peas, yellow smooth peas, green wrinkled peas, and yellow wrinkled peas.

The scientist decides to self-pollinate a pea plant that is a dihybrid for the two traits of interest. Using the principles of Mendelian genetics, determine the predicted phenotypic and genotypic ratios of the resulting progeny.

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Information we are given: Green is genotypically dominant to yellow, smooth is genotypically dominant to wrinkled. Pea color and pea texture are genetically unlinked traits, and therefore follow the Mendelian laws of segregation and independent assortment. The plant in question is a diploid, meaning that it carries two alleles for each genetic trait.

The plant that is being self-pollinated in this study is a dihybrid for the two traits of interest. This means that the plant is genotypically heterozygous for both traits (that is, it carries one dominant allele and one recessive allele for each trait).

Let us first assign alleles for the two traits: we will assign dominant alleles, represented by an uppercase letter, to the genotypically dominant version of ...