AP BIOLOGY

Detailed explanation-1: -Recessive alleles only express their phenotype if an organism carries two identical copies of the recessive allele, meaning it is homozygous for the recessive allele. This means that the genotype of an organism with a dominant phenotype may be either homozygous or heterozygous for the dominant allele.

Detailed explanation-2: -Recessive alleles only show their effect if the individual has two copies of the allele (also known as being homozygous?). For example, the allele for blue eyes is recessive, therefore to have blue eyes you need to have two copies of the ‘blue eye’ allele.

Detailed explanation-3: -A recessive allele is a version of a gene which must be homozygous when inherited in order to be expressed in the phenotype. If it is inherited alongside a dominant allele, the offspring will not express the recessive allele phenotype, just the dominant allele.

Detailed explanation-4: -Only individuals with an aa genotype will express a recessive trait; therefore, offspring must receive one recessive allele from each parent to exhibit a recessive trait. One example of a recessive inherited trait is a smooth chin, as opposed to a dominant cleft chin.

Detailed explanation-5: -Closely related to incomplete dominance is codominance, in which both alleles are simultaneously expressed in the heterozygote.