AP BIOLOGY

Detailed explanation-1: -With eye color, for instance, “B” stands for a brown allele and “b” stands for a blue allele. An organism with two dominant alleles for a trait is said to have a homozygous dominant genotype. Using the eye color example, this genotype is written BB.

Detailed explanation-2: -Examples of Dominant Traits Dark hair is dominant over blonde or red hair. Curly hair is dominant over straight hair. Baldness is a dominant trait. Having a widow’s peak (a V-shaped hairline) is dominant over having a straight hairline.

Detailed explanation-3: -bb is called homozygous recessive. Both genes are the same and recessive. The recessive trait is expressed.

Detailed explanation-4: -Eye colour The allele for brown eyes (B) is dominant over the allele for blue eyes (b). So, if you have one allele for brown eyes and one allele for blue eyes (Bb), your eyes will be brown. (This is also the case if you have two alleles for brown eyes, BB.)

Detailed explanation-5: -Phenotype. The physical appearance of the genotype is called the phenotype. For example, children with the genotypes ‘BB’ and ‘Bb’ have brown-eye phenotypes, whereas a child with two blue-eye alleles and the genotype ‘bb’ has blue eyes and a blue-eye phenotype.