Happy deducing—and remember: The blood never lies, but the pedigree might if you forget the i allele.
| Blood Type (Phenotype) | Possible Genotypes | Antigen on RBC | Antibody in Plasma | | :--- | :--- | :--- | :--- | | | IAIA or IAi | A antigen | Anti-B | | B | IBIB or IBi | B antigen | Anti-A | | AB | IAIB | A and B antigens | None | | O | ii | None (H antigen only) | Anti-A and Anti-B |
If you are searching for the , you are likely either a teacher verifying results, a student checking your work, or a curriculum developer updating your resources. The "UPD" (Updated) tag is critical here—genetics standards and blood typing compatibility rules have nuance, and answer keys from 2015 often contain oversimplifications.