Genetic variation (Edexcel A-level Biology B)

This fully-resourced lesson describes how mutations, the events of meiosis and random fertilisation result in genetic variation. The engaging PowerPoint and accompanying resources have been primarily designed to cover points 8.1 (i) & (ii) of the Edexcel A-level Biology B specification but also includes activities to challenge the students on previous concepts in topics 1 and 2.

The students begin the lesson by having to identify phenotype and species from their respective definitions so that a discussion can be encouraged where they will recognise that phenotypic variation within a species is due to both genetic and environmental factors although this lesson only focuses on the genetic aspect. A range of activities, which include exam-style questions and quick quiz rounds, are used to challenge the students on their knowledge and understanding of substitution mutations, deletions, insertions, the genetic code, crossing over and independent assortment. Moving forwards, the concept of multiple alleles is introduced and students will learn how the presence of more than 2 alleles at a locus increases the number of phenotypic variants. The final section of the lesson focuses on the production of haploid gametes by meiosis and discusses how the random fertilisation of these gametes during sexual reproduction further increases variation.