Understanding Genetics and Blood Types Answer Key

To predict the inheritance of ABO and Rh factors, it’s crucial to grasp basic genetic principles. The ABO system is controlled by a single gene with three alleles: A, B, and O. The Rh factor is determined by a separate gene with two alleles: positive (Rh+) and negative (Rh-). A person’s phenotype is the result of the combination of alleles they inherit from their parents.

When a parent carries both an A and an O allele, for instance, the child can inherit either allele from them. If one parent is Rh-positive and the other Rh-negative, the Rh-negative allele can remain hidden if the Rh-positive parent contributes the dominant Rh+ allele. Thus, the Rh+ allele is more likely to be expressed in the child’s genotype.

Understanding the interactions between these alleles helps predict offspring traits and resolve inheritance questions. By recognizing these patterns, geneticists can offer clearer insights into potential blood group combinations, making it easier to address scenarios like paternity testing or organ donation compatibility.