Unattached earlobes are a dominant trait in humans.Finn and Maggie both have unattached earlobes but their daughter, Celia, does not.If Finn and Maggie have a second child, what is the probability that this child will have attached earlobes?
A) 1/4
B) 1/2
C) 3/4
D) 1
E) 1/8

Question

Quizplus · Accepted Answer

Since both Finn and Maggie have unattached earlobes but their daughter has attached earlobes, it means both parents must be heterozygous (having one allele for unattached earlobes and one for attached). The Punnett square for two heterozygous parents (Uu x Uu, where U = unattached, u = attached) shows that there is a 1/4 chance of having a child with attached earlobes (uu).

Unattached Earlobes Are a Dominant Trait in Humans