A man who is a non-tongue roller (t) marries a woman tongue roller (T) whose father was a non-tongue roller (t) - what would the expected genotype and phenotype percentage for their offspring?

To determine the expected genotype and phenotype percentages for the offspring of this couple, we need to understand the principles of inheritance and the relationship between genotype and phenotype.

In this case, tongue rolling is determined by a single gene, and there are two possible alleles for this gene: dominant allele T (which represents the ability to roll the tongue) and recessive allele t (which represents the inability to roll the tongue). The genotype refers to the genetic makeup of an individual, while the phenotype refers to the observable physical trait.

Since the woman is a tongue roller (T), she must have at least one copy of the dominant allele T. However, since her father was a non-tongue roller (tt), he must have two copies of the recessive allele t. Based on this information, we can determine the genotype possibilities for their offspring.

When these two individuals reproduce, each parent can pass on one of their two alleles to their child. Let's consider the four possible combinations of allele inheritance:

1. The man passes on his non-tongue rolling allele (t), and the woman passes on her tongue rolling allele (T): The child will have a genotype of Tt and will be a tongue roller.

2. The man passes on his non-tongue rolling allele (t), and the woman passes on her non-tongue rolling allele (t): The child will have a genotype of tt and will be a non-tongue roller.

3. The man passes on his tongue rolling allele (T), and the woman passes on her tongue rolling allele (T): The child will have a genotype of TT and will be a tongue roller.

4. The man passes on his tongue rolling allele (T), and the woman passes on her non-tongue rolling allele (t): The child will have a genotype of Tt and will be a tongue roller.

Therefore, there is a 50% chance that the offspring will have the genotype Tt and be a tongue roller, and a 50% chance that the offspring will have the genotype tt and be a non-tongue roller.

In terms of phenotype, the expected percentage is also 50% tongue rollers and 50% non-tongue rollers, since all individuals with the genotype Tt can roll their tongues, while those with the genotype tt cannot.

So, in summary, the expected genotype and phenotype percentages for the offspring of this couple would be 50% Tt (tongue rollers) and 50% tt (non-tongue rollers).