Question

A widow's peak is a V-shaped area of the hairline in the center of the forehead. The allele for having a widow's peak is dominant to the allele for not having a widow's peak.

If two parents do not have widow's peaks, what is the probability that their child will have a widow's peak?
A.
75%
B.
0%
C.
25%
D.
50%

Answer 1

B.

0%

Step-by-step explanation:

A widow's peak is a V-shaped point in the hairline in the center of the forehead. Hair growth on the forehead is suppressed in a bilateral pair of periorbital fields. Without a widow's peak, these fields join in the middle of the forehead so as to give a hairline that runs straight across.

Answer 2

Well knowing that this is a simple complete dominance type of problem, where a single set of alleles for the trait dictate what the phenotype is and that the dominant allele hides the recessive allele.

V - allele for widow's peak
v - allele for no widow's peak.

In order for the parents not to have widow's peak they would need to be homozygous recessive, as this is the only allelic combination where they will lack a least one dominant form of the allele.

vv • vv

From the cross all children will NOT have widow's peak as it is not a possible allele either of the parent's can give and thus the solution is B. 0%.

The solution is B. 0%.