In a polygenic trait
A) all genes contribute equally.
B) within genes, all alleles affect the phenotype to the same degree.
C) all alleles are dominant.
D) genes contribute to varying degrees, and alleles have differing degrees of impact.
E) one gene can cancel out the effect of the environment.

Question

Quizplus · Accepted Answer

In a polygenic trait, multiple genes contribute to the phenotype and each gene can have multiple alleles. These genes contribute to varying degrees, and alleles have differing degrees of impact on the phenotype. Thus, choice D is the best option. Choice A is incorrect because all genes do not contribute equally. Choice B is incorrect because within genes, some alleles may have more influence than others. Choice C is incorrect because not all alleles are dominant. Choice E is incorrect because one gene cannot cancel out the effect of the environment on a polygenic trait.

In a Polygenic Trait