Question

Corn kernels can have a purple color due to the dominant allele of one gene. When the alleles of a second gene are present in the homozygous recessive genotype, the kernel color is changed to red. This is an example of ______?

1) Incomplete dominance
2) Codominance
3) Polygenic inheritance
4) Epistasis

Answer 1

Corn kernel color change from purple to red due to a homozygous recessive genotype in a second gene is an example of epistasis, where one gene's expression is influenced by another gene.

Step-by-step explanation:

The color phenomenon described in corn kernels, where a dominant allele causes purple color but a second gene can change the color to red when homozygous recessive, is an example of epistasis. Epistasis occurs when the expression of one gene is affected by the genotype of another gene. In this case, the corn kernel color is determined by two different genes that interact with each other.

The dominant allele for the first gene allows for purple color, but the presence of two recessive alleles in the second gene overrides this effect, leading to red kernels. This is distinctly different from incomplete dominance or codominance which is usually seen in the interaction between two alleles at a single locus. Polygenic inheritance, which involves many genes contributing to a single trait, is also not demonstrated in this scenario.