Question

In humans, the trait for tongue rolling is dominant over the trait for the inability of a human to roll his/her tongue. If a heterozygous male is crossed with a homozygous recessive female, then what percent of the offspring would be expected to have the ability to roll their tongues

Answer 1

Answer: 50% of offspring can roll their tongues

Explanation:

Since tongue rolling is a dominant trait, if the father is heterozygous for it, his genotypes could be Tt, since he has a the dominant allele for tongue rolling, this means he can roll his tongue

Since the mother is homozygous recessive, this means she cannot roll her tongue, her genotype is tt

If you do a punnet square and you cross the mom and dad, the offspring will have the following genotypes:

Tt, tt, Tt, tt

50% of the offspring will be heterozygous for tongue rolling, which means they will be able to roll their tongues as they have the dominant allele.

While the other 50% will not have the tongue rolling trait because they will be homozygous recessive and not have the dominant allele

Answer 2

50% will be heterozygous dominant, 50% will be homozygous recessive. This was according to a traditional Punnett square.