4BI1
Ecology & Food Chains
Ecology and the Environment · 8 question types
Exam Frequency Analysis
Past paper frequency (2018 to 2024)
This topic accounts for approximately 12% of your exam marks.
stable
High
Stable12%
Food chains, energy transfer, and ecological definitions are regularly tested, often as short-answer questions.
Ecology is the branch of biology that studies how organisms interact with each other and with their environment. The subject has its own set of precise terms, and many exam questions hinge on using them correctly.
Five terms you need to know
| Term | Meaning | Example |
|---|---|---|
| Population | A group of organisms of the same species living in the same area at the same time | All the grey squirrels in Hyde Park |
| Community | All the populations of different species living in the same area at the same time | All the squirrels, robins, oak trees, foxes, worms and mushrooms in Hyde Park |
| Habitat | The place where an organism lives | A woodland; a pond; a coral reef; a damp log |
| Ecosystem | A community of organisms plus the non-living factors of the area, all interacting together | A whole woodland (organisms + soil + climate + light + water) |
| Biosphere | All the ecosystems on Earth combined | The entire global ecosystem |
The progression goes from small to large:
single organism → population → community → ecosystem → biosphere
Ecosystems vary hugely in size. A small ecosystem might be a garden pond; a large one might be the whole of the Sahara Desert.