Tongue-curling in humans is a dominant genetic trait.

a) suppose a man who is Tt for tongue-curling marries a woman who is also Tt for this trait. What are the possible genotypes and phenotypes of the offspring? What is percentage chance of each type?

-Genotypes: 25% TT, 50% Tt, 25% tt.

-Phenotypes: 75% have the trait for tongue curling, the other 25% do not have the trait for tongue curling.

-Percentage change of each type: 25% TT (homozygous dominant), 50% Tt (heterozygous), and 25% tt (homozygous recessive).

Explanation:

So to calculate the probably of off spring, we usually make a Punnett square.

Since a Tt man marries a Tt woman, they produce "offspring" (babies) that look like this in a Punnett square:

TT Tt

Tt tt

Looking from this Punnett square, we have one that is TT, two that are Tt, and one that is tt, a total of four. Your genotypes are the genetical traits, so out of the four, you take a percentage and calculate the genes: 25% TT, 50% Tt, and 25% tt. Your phenotypes are your physical traits, so 75% will have the "tongue-curling" trait as the trait T is dominant in three of them (TT, Tt, and Tt), and the other 25% will NOT have the trait.

T t

T TT Tt

t Tt tt

Roughly 1/4 of their offspring will not have the tongue-curling gene. The possible genotypes are TT (Has), Tt (Has), tt (Doesn't have)