MCQ
In human, tongue rolling is a dominant trait $(R)$, those with the recessive condition cannot roll their tongues. Mohan can roll his tongue, but his mother could not. He is married to Surekha, who cannot roll her tongue. What is the probability that their first born child will not be able to roll his tongue?
  • A
    $0 \%$
  • B
    $30 \%$
  • C
    $100 \%$
  • $50 \%$

Answer

Correct option: D.
$50 \%$
(d) $50 \%$
Explanation:
For the given question the Alleles will be: ' $R$ ' - Tongue rolling and' $r^{\prime}$ - no tongue rolling. As Mohan's mother cannot roll Mohan is a heterozygous tongue roller ( Rr ).
The wife being a nonroller (rr), the child will be:
Image

Phenotype Ratio is $2 Rr : 2 rr$ that is $1: 1$. Therefore $50 \%$ will be tongue roller and $50 \%$ will be non-tongue roller.
Because of complete dominance if the child is heterozygous it will have a phenotype of a tongue roller.

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