Question

A child without dimples is born to parents both of which bear dimples. If the allele for dimple 'D' is dominant over recessive allele 'd' (without dimples), then the possible genotypes of parents would be

I. DDand Dd

II. Ddand Dd

III. DDand dd

• A. I only
• B. II only
• C. I or II
• D. II or III
• E. I, II and III

Answer 1

Answer: (B)

II only

Since "without dimple, d" allele is recessive, a child without dimple can be borne to the parents having atleast one "d" allele. This rules out the possiblily of options I and III to be parents as one parent in homozygous dominant on both options. Parents in option II are heterozygous dominant and both of them carry one copy of "d" allele, enough to have a child with "dd" genotype and "without dimple" phenotype.

Therefore, the correct answer is option B.