Question

1. in humans, being a tongue roller (r) is dominant over non - roller (r). a man who is a non - roller marries a woman who is heterozygous for tongue rolling.

father’s phenotype ____ mother’s phenotype ____
father’s genotype ____ mother’s genotype ____
what is the probability of this couple having a child who is a tongue roller? ______

Explanation:

Step1: Determine Genotypes

The father is a non - roller. Since non - roller is recessive (r), his genotype must be \( rr \) (phenotype: non - tongue roller). The mother is heterozygous for tongue rolling, so her genotype is \( Rr \) (phenotype: tongue roller).

Step2: Set up Punnett Square

The father can only produce \( r \) gametes. The mother can produce \( R \) and \( r \) gametes.

	R	r
r	Rr	rr

Step3: Calculate Probability of Tongue Roller (Rr)

From the Punnett square, out of 4 possible offspring genotypes, 2 are \( Rr \) (tongue rollers) and 2 are \( rr \) (non - rollers). The probability is \( \frac{2}{4}=\frac{1}{2} \) or 50%.

Father's phenotype: non - tongue roller

Mother's phenotype: tongue roller

Father's genotype: \( rr \)

Mother's genotype: \( Rr \)

Answer:

Father's phenotype: non - tongue roller; Mother's phenotype: tongue roller; Father's genotype: \( rr \); Mother's genotype: \( Rr \); Probability of tongue - roller child: 50% (or \( \frac{1}{2} \))