Final answer:
When a homozygous brown-eyed individual (BB) is crossed with a homozygous blue-eyed individual (bb), the result is 100% heterozygous brown-eyed (Bb) offspring. Therefore, all offspring from this cross will show the dominant brown eye color, giving a phenotypic ratio of 100% brown eyes.
Step-by-step explanation:
In humans, brown eyes are dominant over blue eyes. In a genetic cross between two individuals where one parent has homozygous brown eyes (BB) and the other parent has homozygous blue eyes (bb), all the offspring will inherit a B allele from the brown-eyed parent and a b allele from the blue-eyed parent. Since the presence of at least one brown allele (B) is sufficient to give brown eyes because it is dominant, all of the offspring will have brown eyes.
The genotype of the offspring will be heterozygous (Bb), resulting in 100% of the offspring having brown eyes. The phenotypic ratio of brown-eyed to blue-eyed offspring is therefore 100% brown and 0% blue eyes, because the brown allele completely masks the expression of the blue allele in this case.