A brown-eyed man marries a blue-eyed woman and they have eight children, all with brown eyes. Can you be sure whether the man is homozygous or heterozygous for eye color?
If heterozygous, the probability of all 8 getting the dominant gene by chance = .5^8 = .004
Although I cannot be absolutely sure, I would reject the heterozygous hypothesis at the P ≤ .01 Level.
To determine whether the man is homozygous or heterozygous for eye color, we need to understand the inheritance pattern of eye color. Eye color is determined by genes, specifically alleles for eye color, which can be either dominant or recessive.
Let's denote the allele for brown eyes as "B" (dominant) and the allele for blue eyes as "b" (recessive).
If the brown-eyed man is homozygous for eye color (BB), he only carries the dominant allele for brown eyes. In this case, all of his offspring would inherit one allele for brown eyes from him, making it impossible for any of them to have blue eyes. Hence, it would be certain that the man is homozygous for brown eyes.
On the other hand, if the man is heterozygous for eye color (Bb), he carries both the dominant allele for brown eyes and the recessive allele for blue eyes. In this case, each child would have a 50% chance of inheriting the dominant allele for brown eyes (B) and a 50% chance of inheriting the recessive allele for blue eyes (b). However, since all of their children have brown eyes, it is still possible (but less likely) that the man is heterozygous instead of homozygous.
Based on the information given, we cannot be entirely sure whether the man is homozygous or heterozygous for eye color.