Which genotypes code for being a PTC taster?

• A. TT only
• B. TT and Tt
• C. Tt and tt
• D. tt only

Answer: (B)

Verified step by step guidance

1. Understand the concept of PTC tasting: PTC (phenylthiocarbamide) tasting is a genetic trait controlled by a single gene with two alleles, T (taster) and t (non-taster).
2. Identify the dominant and recessive alleles: The allele T is dominant, meaning that having at least one T allele will result in the ability to taste PTC. The allele t is recessive, meaning that two copies of t (tt) are needed for the non-taster phenotype.
3. Determine the genotypes: The genotypes that code for being a PTC taster are TT and Tt. Both of these genotypes contain at least one dominant T allele, which is sufficient for the taster phenotype.
4. Explain the genotype TT: The genotype TT consists of two dominant alleles, which clearly results in the taster phenotype.
5. Explain the genotype Tt: The genotype Tt consists of one dominant allele and one recessive allele. The presence of the dominant T allele is enough to express the taster phenotype.