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?

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.

it is called the mitotic spindle