Levels of organisation within an ecosystem
Levels of organisation within an ecosystem - Trophic levels
The principle of material cycling
Challenges of increasing food yields using fewer resources
Sample exam questions
(a) The diagram below shows a pyramid of biomass for the trophic levels of organisms in a habitat.
Many species of butterflies and other insects have declined considerably in the UK since 1950.
(a) (i) Calculate the number of alien species that are in Britain today.