In humans, a type of blindness is due to a dominant allele (B). Normal vision is the result of a
recessive allele (b). Migraine headaches are due to a dominant allele (M), and normal (no migraines)
is recessive (m).
A male who is heterozygous for blindness and does not suffer from migraines marries a woman who
has normal vision and does not suffer from migraines.
Could they produce a child with normal vision who does not suffer from headaches? If yes, can the
probability of such a child be determined?
You must draw a Punnett square within the space provided to receive any credit for your answer!

This question involves two distinct genes in humans. One coding for blindness and the other for Migraine headaches. The alleles for blindness (B) and Migraine (M) are dominant over the alleles for normal vision (b) and no Migraine (m).

According to the question, a male who is heterozygous for blindness and does not suffer from migraines will have the genotype; Bbmm while a female who

has normal vision and does not suffer from migraines will have genotype; bbmm. If these two parents are crossed, the following genotypes of gametes will be produced by each parent:

Bbmm- Bm, Bm, bm and bm

bbmm- bm, bm, bm, and bm

Using these gametes to construct a punnet square (see attached image), the following offsprings with genotypes; Bbmm and bbmm in the ratio 1:1 will be produced.

Bbmm (8/16) are offsprings with blindness and have no Migraine headache

bbmm (8/16) are offsprings with normal vision and have no migraine headache

Hence, this cross can produce a child with normal vision who does not suffer from headaches (bbmm). Also, the probability of producing such child is 8/16 or 1/2.