Question

Looking at hairline (widow's peak = H) and PTC tasting ability (tasting = M)... If a man who is HHmm has children with a woman who is HhMm, what percentage of their children will be able to taste PTC?

Question 5 options:

a. 50%
b. 38%
c. 100%
d. 56%
e. 67%

Answer 1

A man with genotype HHmm and a woman with HhMm will have 75% of their children able to taste PTC because PTC tasting is an incompletely dominant trait and three out of the four possible genetic combinations can taste PTC.

Step-by-step explanation:

The percentage of their children who will be able to taste PTC is 75%.

The genetics of PTC tasting ability is an example of a trait that follows Mendelian inheritance; specifically, PTC tasting is an incompletely dominant trait. The man has the genotype HHmm, which means he is homozygous dominant for the widow's peak but homozygous recessive for the PTC tasting allele (cannot taste PTC). The woman is HhMm, indicating that she is heterozygous for both traits.
For the offspring to taste PTC, they need to inherit at least one 'M' allele. When creating a Punnett square, the possible genotypes for their children are HM, Hm, hM, and hm. Since the ability to taste PTC is incompletely dominant, both HM and Hm genotypes will result in a child who can taste PTC. This leads to three out of the four possible combinations being able to taste PTC, resulting in a 75% chance that any given child will be able to taste PTC.