Question

The ability to taste the chemical phenylthiocarbamide is an autosomal dominant phenotype, and the inability to taste it is recessive. If a taster woman with a nontaster father marries a taster man who, in a previous marriage, had a nontaster daughter, what is the probability that their first child will be:____
a) a nontaster girl?
b) a taster girl?
c) a taster boy?

Answer 1

Answer:

Option A

Explanation:

Autosomal dominant means that even a single affected allele in genotype of offspring can cause the disease.That means one carrier parent is sufficient to pass on the autosomal dominant disease to its next generation.  

Given –  

Woman is taster and father is nontatster. They mate and produce a nontaster daughter.  

Hence, the genotype of the parents would be  

Mother – XX’

Father – Y’X

Here allele “X” represents the non taster allele while the allele “ X’  and Y’ ” represents the taster allele

Cross between  XX’ and Y’X

XY’, XX, X’Y’, XX’

Thus, the parents will have a taster boy