Question

Dimples and long eyelashes are both autosomal dominant traits. If a woman with no dimples, who is heterozygous for long eyelashes, mates with a man who is heterozygous for dimples, and has short eyelashes,a) What is the woman's genotype?b) What is the man's phenotype?c) What are the chances that this couple produces a child without dimples?d) What are the chances that this couple produces a child without dimples AND without long eyelashes?

Answer 1

Answer:

a) aaBb

b) Dimples and short eyelashes

c) 50%

d) 25%

Explanation:

Let the gene for dimples be A

Let the gene for eyelashes be B

a) Woman has no dimples (aa) and is heterozygous for long eyelashes (Bb) so her genotype : aaBb

b) Man is heterozygous for dimples (Aa) so he will have dimples and it is already given that he has short eyelashes (bb)

When aaBb X Aabb :

        aB         ab

Ab  AaBb    Aabb

ab   aaBb    aabb

c) Out of the four possible combinations, aaBb and aabb will be born without dimples so this couple has 50% chance to produce a child without dimples.

d) Only aabb will be born without dimples and without long eyelashes so the couple has 25% chance to produce a child without dimples and without long eyelashes.