AP BIOLOGY

Detailed explanation-1: -A dominant allele is denoted by a capital letter (A versus a). Since each parent provides one allele, the possible combinations are: AA, Aa, and aa. Offspring whose genotype is either AA or Aa will have the dominant trait expressed phenotypically, while aa individuals express the recessive trait.

Detailed explanation-2: -For example, with two genes each having two alleles, an individual has four alleles, and these four alleles can occur in 16 different combinations.

Detailed explanation-3: -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-4: -This means that the genotype of an organism with a dominant phenotype may be either homozygous or heterozygous for the dominant allele.

Detailed explanation-5: -If both alleles are dominant, it is called codominance?. The resulting characteristic is due to both alleles being expressed equally. An example of this is the blood group AB which is the result of codominance of the A and B dominant alleles.