The lesson began with a review of biodiversity concepts and definitions of abiotic and biotic factors that affect ecosystems. Nicky explained various environmental factors and their impacts on organisms, using a seaside habitat as an example to demonstrate adaptations and methods for measuring biological diversity. The lesson concluded with discussions on trophic levels and food chains, including a detailed example of how changes in one part of a food chain can affect the entire ecosystem, followed by an exploration of marine ecosystems and their interdependencies.