Question

Imagine that beak color in a finch species is controlled by a single gene. You mate a finch homozygous for orange (pigmented) beak with a finch homozygous for ivory (unpigmented) beak and get numerous offspring, all of which have a pale, ivory-orange beak. This pattern of color expression is most likely to be an example of

Answer 1

Answer: Incomplete dominance

Explanation: Incomplete dominance is a type of inheritance, specifically a type of intermediate inheritance when a dominant allele, or form of a gene, does not completely mask the effects of a recessive allele, and the organism’s resulting physical appearance shows a blending of both alleles. The result is a phenotype (expression) where the expressed physical trait is a combination of both of the phenotypes that belong to the alleles. One allele doesn’t mask or dominate the other alleles in this instance. It is also called semi-dominance or partial dominance.

In short, incomplete dominance is when neither gene is fully dominant, and the result is a brand new trait.

The Punnett square shows genetic inheritance as a simple model with only two different versions of alleles: dominant and recessive. In this simple relationship, dominant alleles always override the recessive alleles to be expressed in the organism’s appearance or phenotype. It was created by Gregor Mendel and was important because it contradicted popular ideas at the time that the traits of the parents were simply permanently blended within their offspring. However, modern biologists have discovered that inheritance isn’t as simple as this model would suggest.

An example of incomlete dominance in humans would be hypercholesterolemia.