Question

Dr. Smith's parents have normal hearing. However, Dr. Smith has an inherited form of deafness. Deafness is a recessive trait that is associated with the abnormal allele d. The normal allele at this locus, associated with normal hearing, is D. Dr. Smith's parents could have which of the following genotypes? (a) Dd and DD (b) Dd and Dd (c) DD and dd (d) dd and dd

Answer 1

Answer:

Option B, Dd and Dd

Explanation:

It is given that deafness is a recessive trait.

Let the recessive trait be represented by "d"

Normal hearing is a dominant trait and let it be represented by "D"

It is given that Dr. Smith's parents have normal hearing , hence they can have genotype -

either Dd  X  DD

Or      Dd X Dd

but Dr. Smith has an inherited form of deafness , thus his genotype would be "dd". Considering the genotype of Dr. Smith , his parents would be having genotype Dd and Dd.

Thus option B is correct.