AP BIOLOGY

Detailed explanation-1: -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. An organism with one dominant allele and one recessive allele is said to have a heterozygous genotype. In our example, this genotype is written Bb.

Detailed explanation-2: -An individual that contains two different alleles of a gene is heterozygous. Examples. A cow that has two alleles for a red coat is homozygous (bb). A bull with two alleles for a black coat is homozygous (BB). A calf that has one allele for red coat color and one allele for black coat color is heterozygous (Bb).

Detailed explanation-3: -An organism can be either homozygous dominant ( TT ) or homozygous recessive ( tt ). If an organism has two different alleles ( Tt ) for a certain gene, it is known as heterozygous (hetero-means different).

Detailed explanation-4: -Individuals who are homozygous dominant (DD) or heterozygous (Dd) are Rh+. Those who are homozygous recessive (dd) are Rh-(i.e., they do not have the key Rh antigens).

Detailed explanation-5: -Genotypes with two alleles that are the same, i.e. ‘BB’ and ‘bb’, are known as homozygous genotypes and genotypes with two different alleles are known as heterozygous genotypes.