Question

question 34
jons parents have normal hearing but jon has an inherited form of deafness. deafness is a recessive trait that is associated with the
abnormal allele d. the allele for normal hearing is d. jons parents could have which of the following genotypes?

1. dd and dd
2. dd and dd
3. dd and dd
4. dd and dd

Explanation:

• Deafness is a recessive trait. So, Jon must have the genotype \(dd\) (as recessive traits are expressed in homozygous recessive condition).
• Since Jon's parents have normal hearing, they cannot have the genotype \(dd\) (because \(dd\) would mean deafness).
• For parents with normal hearing (\(D-\)) to have a child with \(dd\) genotype (Jon), each parent must contribute a \(d\) allele. So, both parents must be heterozygous (\(Dd\)).

Answer:

1. \(Dd\) and \(Dd\)