for practice, let's work with blood groups. three alleles exist for human blood types. they were not numbered, but instead marked with the letters for a, b and o. the labeling convention is : ia, ib, and ii. ia and ib are codominant alleles, whereas ii is the recessive allele for type o. humans are diploid; every individual carries only two alleles. for the following question list all 6 possible blood group genotypes. the first has been done for you below: