Humans have a gene, T, that is involved in muscle formation of the tongue. Individuals homozygous for one allele can roll their tongues, while individuals homozygous for the other allele cannot. If both parents can roll their tongues, but their child cannot, what can be said about the mode of inheritance?
A) The parents were both homozygous, but the child was heterozygous.
B) Tongue rolling is recessive, and both parents were heterozygous (Tt).
C) Tongue rolling is recessive.
D) Tongue rolling is dominant.
E) Tongue rolling is dominant, and both parents were heterozygous (Tt).

Question

Quizplus · Accepted Answer

Tongue rolling is a dominant trait, and for both parents to be able to roll their tongues but produce a child who cannot, they must both be heterozygous. This means they each carry one allele for tongue rolling and one allele for not being able to roll the tongue. The child inherited the non-rolling allele from each parent.

Humans Have a Gene, T, That Is Involved in Muscle