Understanding codominance (Pearson Edexcel IGCSE Biology)

This fully-resourced lesson has been designed to cover the specification point 3.21B (understanding the term co-dominance) as detailed in topic 3 (Reproduction and inheritance) of the Pearson Edexcel IGCSE Biology specification. The lesson uses the inheritance of the ABO blood group system to demonstrate co-dominance. A potentially difficult topic, time has been taken to include guidance sections where students are walked through the interpretation of the different genotypes to find out the phenotypes as well as supporting them through the construction of genetic diagrams and working out the blood groups from pedigree trees. There is a real focus on genetic terminology such as allele, locus, genotype and phenotype so that the understanding is deep and students can use this if they choose to further their studies at A-level.

This lesson has been designed for GCSE-aged students studying the Pearson Edexcel IGCSE Biology course but is also suitable for older students who are learning about codominance (and multiple alleles) at A-level