AP BIOLOGY

Detailed explanation-1: -When discussing genotype, biologists use uppercase letters to stand for dominant alleles and lowercase letters to stand for recessive alleles. With eye color, for instance, “B” stands for a brown allele and “b” stands for a blue allele.

Detailed explanation-2: -Eye color was traditionally described as a single gene trait, with brown eyes being dominant over blue eyes. Today, scientists have discovered that at least eight genes influence the final color of eyes.

Detailed explanation-3: -The Single Gene Trait There is one genetic variation, a human trait that has a single gene governing it, and that is eye color which is blue or brown. Brown eyes are dominant and blue eyes recessive.

Detailed explanation-4: -The allele for brown eyes (B) is dominant, while the allele for blue eyes (b) is recessive. A man with genotype bb and a woman with genotype BB have four children.

Detailed explanation-5: -The bey2 gene has one allele for brown eyes and one for blue eyes. The allele for brown eyes is the most dominant allele and is always dominant over the other two alleles and the allele for green eyes is always dominant over the allele for blue eyes, which is always recessive.