Question

You are examining two traits of a plant called Trait A and Trait B. Each trait is associated with a different gene on a different chromosome. Trait A shows: the same phenotype for both the heterozygous and homozygous dominant allele combinations a different phenotype for the homozygous recessive allele combination. Trait B shows: three different phenotypes, each associated with only one of the three possible allele combinations. A) Describe the type of inheritance associated with Trait A and describe the type of inheritance associated with Trait B. In your own words explain how you arrived at each of your answers. B) Your plant is displaying the Trait A phenotype associated with a homozygous dominant or heterozygous allele combination. In your own words, explain how you would determine which allele combination is present in your plant.

Answer 1

A) Trait A is showing the complete dominance inheritance. Because the homozygous dominant and heterozygous genotype have same phenotype. But the different phenotype is obtainer in homozygous recssive genotype.

Trait B is showing the incomplete dominance. Here the three phenotypes are obtained. Homozygous dominant produces first phenotype. Heterozygous produces second phenotype and homozygous recessive produces third phenotype.

B) The test cross is done to determine the genotype of homozygous dominant or heterozygous ones. We will cross the unknown parent with homozygous recessive one. If all progeny shows dominant phenotype, then the genotype of unkown parent is homozygous dominant. But the heterozygous genotype produces half dominant and half recessive phenotype bearing individual.