Q.16 A man having a dominant genetic trait (TT genotype) can taste
phenylthiocarbamide (PTC), marries a woman who cannot taste PTC. The PTC
tasting ability of their biological son and daughter is
(A) Son taster; Daughter non–taster
(B) Daughter taster; Son non–taster
(C) Both are non–tasters
(D) Both are tasters
PTC tasting follows simple dominant inheritance where T (taster) dominates t (non-taster). A homozygous TT man produces only T gametes, while his tt wife produces only t gametes.
Parental Genotypes
Man: TT (homozygous dominant taster).
Woman: tt (homozygous recessive non-taster).
Cross: TT × tt yields 100% Tt offspring, all tasters.
Punnett Square Analysis
| T | T
---------
t | Tt| Tt
t | Tt| Tt
All progeny Tt genotype, expressing taster phenotype regardless of son or daughter.
Option Explanations
A) Son taster; Daughter non-taster – Incorrect. Tt daughters taste PTC; non-taster requires tt, impossible from TT father.
B) Daughter taster; Son non-taster – Incorrect. No sex-linkage; PTC autosomal, all Tt children taste.
C) Both non-tasters – Incorrect. Non-taster (tt) needs two t alleles; father contributes T to all.
D) Both tasters – Correct. All offspring Tt heterozygous tasters.
CSIR NET Relevance
This tests monohybrid inheritance and genotype-phenotype mapping, common in Unit 5 (Developmental Biology & Genetics). Practice Punnett squares for homozygous-dominant × recessive crosses yielding uniform heterozygotes.
SEO Introduction
PTC tasting TT genotype man marries non-taster woman: All biological son and daughter are tasters. Understand phenylthiocarbamide inheritance, dominant T allele ensures 100% Tt progeny in CSIR NET genetics problems.
