Which of the following terms describes an interaction between two genes?

Three pairs of genes with two alleles each (A₁ and A₂, B₁ and B₂, and C₁ and C₂) control the height of a plant. The alleles of these genes have an additive relationship: Each copy of alleles A₁, B₁, and C₁ contributes 6 cm to plant height, and each copy of alleles A₂, B₂, and C₂ contributes 3 cm.

What are the expected heights of plants with each of the homozygous genotypes A₁A₁B₁B₁C₁C₁ and A₂A₂B₂B₂C₂C₂. 

A plant line with reduced fertility comes to the attention of a plant breeder who observes that seed pods often contain a mixture of viable seeds that can be planted to produce new plants and withered seeds that cannot be sprouted. The breeder examines numerous seed pods in the reduced fertility line and counts 622 viable seeds and 204 nonviable seeds.

Propose an additional experiment to test the genetic mechanism you propose. If your hypothesis is correct, what experimental outcome do you predict?

A plant line with reduced fertility comes to the attention of a plant breeder who observes that seed pods often contain a mixture of viable seeds that can be planted to produce new plants and withered seeds that cannot be sprouted. The breeder examines numerous seed pods in the reduced fertility line and counts 622 viable seeds and 204 nonviable seeds.

What single-gene mechanism best explains the breeder's observation?

Polygenic traits are controlled through which of the following ways.

Polygenic traits are usually continuous traits?

Which of the following traits would you expect to be inherited as quantitative traits?

coat color in dogs

For the traits listed in the previous problem, which do you think are likely to be multifactorial traits, with phenotypes that are influenced by genes and environment? Identify two environmental factors that might play a role in phenotypic variation of the traits you identified.