Epistasis (AQA A-level Biology)

This fully-resourced lesson explores how the presence of particular alleles at one locus can mask the expression of alleles at a second locus in epistasis. The detailed and engaging PowerPoint and associated resources have been designed to cover the part of point 7.1 of the AQA A-level specification which states that students should be able to use fully-labelled genetic diagrams to predict or interpret the results of crosses involving epistasis.

This is a topic which students tend to find difficult, and therefore the lesson was written to split the topic into small chunks where examples of dominant, recessive and complimentary epistasis are considered, discussed at length and then explained. Understanding checks, in various forms, are included throughout the lesson so that students can assess their progress and any misconceptions are immediately addressed. There are regular links to related topics such as dihybrid inheritance so that students can meet the challenge of interpreting genotypes as well as recognising the different types of epistasis.

The lesson has been designed to tie in with the other uploaded lessons on the topic of inheritance (7.1), so if you like the quality of this lesson please take a moment to look at these too


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  • Epistasis.pptx
  • Gene-interactions-exam-questions.docx
  • Complimentary-epistasis-understanding-check--2.docx

About this resource


Created: Oct 11, 2019

Updated: Oct 16, 2019

pptx, 6 MB


docx, 15 KB


docx, 15 KB


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Creative Commons "Sharealike"

Creative Commons "Sharealike"