AP Biologymediummcq1 pt

A researcher is studying the inheritance of a trait in mice. He observes that the offspring of two heterozygous parents (Mm) have a 3:1 ratio of M:Mm:m:Mm. Which of the following is the most likely explanation for this ratio?

A.A) The parents are not truly heterozygous

B.B) There is a mutation in the gene

C.C) The trait is influenced by multiple genes

D.D) The primary reason is incomplete dominance

Explanation

Core Concept

In a scenario where the offspring of two heterozygous parents have a 3:1 ratio of M:Mm:m:Mm, the most likely explanation is incomplete dominance. This occurs when the dominant allele is not completely dominant over the recessive allele, resulting in a blend of the two phenotypes.

Correct Answer

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