How are ABO blood groups genetically transmitted?

The ABO blood group is an example of codominance and multiple alleles. Unlike other characteristics which are determined by 2 alleles, blood group is determined by 3 alleles. The allele IA corresponds to blood group A (genotype IA IA ) and the allele IB corresponds to blood group B (genotype IB IB) . Both these are dominant so if IA and IBare present together they form blood group AB (genotype IAIB ). The allele i is recessive to both IA and IB and hence if you have genotype IAi you will have blood group A and if you have genotype IAi you will have blood group A and if you have the genotype IB i you will have blood group B. However, if you have the genotype ii then you are homozygous for i, and you will have blood group O.

Related Biology IB answers

All answers ▸

explain the breakdown of erythrocytes in the body


I know all the theory, but I can never score well with the essay questions in paper 2. Why?


What is the difference between sister chromatids and homologous chromosomes?


Cells go through a repeating cycle of events in growth regions such as plant root tips and animal embryos. Outline this cell cycle.


We're here to help

contact us iconContact usWhatsapp logoMessage us on Whatsapptelephone icon+44 (0) 203 773 6020
Facebook logoInstagram logoLinkedIn logo
Cookie Preferences