Codominant and multiple alleles (AQA A-level Biology)

This fully-resourced lesson covers the part of specification point 7.1 of the AQA A-level Biology specification which states that students should be able to use genetic diagrams to interpret the results of crosses involving codominant and multiple alleles. The inheritance of ABO blood groups has three alleles at the gene locus on chromosome 9 where the alleles for A and B are codominant and this is used to introduce the two concepts. A range of tasks challenges the students to write genotypes, and construct genetic diagrams to calculate phenotypic ratios. They have to apply their understanding by working out the blood groups for a number of family members when presented with an incomplete pedigree tree. The final task of the lesson challenges their application skills further but this time, the animals involved are not humans. Each question is followed by a detailed, visual mark scheme so students can assess their progress and address any misconceptions


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  • Codominance-and-multiple-alleles.pptx
  • Understanding-the-inheritance-of-blood-groups-and-applying-knowledge.docx
  • Understanding-the-inheritance-of-blood-groups-and-applying-knowledge-STARS.docx
  • APPLICATION---Codominance-and-multiple-alleles-questions.docx

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Created: Oct 10, 2019

Updated: Oct 16, 2019

pptx, 2 MB


docx, 20 KB


docx, 25 KB


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Creative Commons "Sharealike"

Creative Commons "Sharealike"