To solve the mystery, students must apply the following rules of ABO blood type inheritance : The ABO gene has three alleles: IAcap I to the cap A-th power IBcap I to the cap B-th power Codominance: IAcap I to the cap A-th power IBcap I to the cap B-th power are codominant, meaning both are expressed in Type AB ( IAIBcap I to the cap A-th power cap I to the cap B-th power Recessiveness: The allele (Type O) is recessive. A person must have two ) to have Type O blood.
IAIBrrcap I to the cap A-th power cap I to the cap B-th power r r : Phenotype , Genotype iirri i r r : Phenotype AB- , Genotype lab activity blood type pedigree mystery answer key