Question

There are two alleles for the PTC-tasting locus in humans: T, which codes for tasting, and t, which codes for non-tasting. T is dominant and t is recessive. Imagine two parents that are tasters have a child that is a non-taster. Given this information, you know that the genotypes of the parents had to have been

Answer 1

If two PTC taster parents have a non-tasting child, both parents must be heterozygous (Tt) for the PTC-tasting gene, as their child would be homozygous recessive (tt) and express the non-tasting phenotype.

Step-by-step explanation:

The question deals with basic genetics and inheritance patterns. Specifically, this question is asking about the inheritance of the PTC-tasting ability in humans, where T is the dominant allele for tasting and t is the recessive allele for non-tasting. If two parents who can taste PTC (tasters) have a child who cannot taste PTC (non-taster), the only way this can happen is if both parents were heterozygous for the gene, which means their genotypes were Tt. Since both parents have one tasting allele (T) and one non-tasting allele (t), their child could inherit a non-tasting allele (t) from each parent, resulting in the genotype tt, which is homozygous recessive and expresses the non-tasting phenotype.