Ecology and environment for N(A)-Level Science (Biology): food chains and energy flow, the carbon cycle, and the impact of human activity on the environment

What this module covers

Ecology and environment is about how living things interact with each other and with their surroundings. You need to describe food chains and food webs and explain how energy flows from the Sun and is lost along the way, describe the carbon cycle, and describe the impact of human activity on the environment and ways to reduce the harm.

This overview links every dot point in the module. Work through them in order, then check yourself with the questions at the end. See the full set at /sg-n-level/biology/syllabus.

Food chains and energy flow

Start with how energy moves through living things. The page on food chains and energy flow describes producers and consumers, how food chains link into food webs, and why energy is lost at each step so that chains stay short.

The carbon cycle

Next, how a key element is recycled. The page on the carbon cycle describes how carbon moves between the air, plants and animals through photosynthesis, respiration, decomposition and combustion.

Human impact on the environment

Finally, how people change the environment. The page on human impact on the environment describes how pollution, deforestation and the greenhouse effect harm the environment, and the steps people can take to reduce the damage.

How this module is examined

At N(A) level there is no standalone pure Biology paper. Biology is taken as part of a combined Science subject, either Science (Physics, Biology) syllabus 5106 or Science (Chemistry, Biology) syllabus 5107, so this module is examined within whichever combination your school offers.

• Get the arrows right. Food chain answers reward arrows pointing in the direction energy flows, from producer to consumer.
• Name the four processes. Carbon cycle answers reward naming photosynthesis (removes carbon dioxide) and respiration, decomposition and combustion (return it).
• Pair problem with solution. Human impact answers reward linking a named problem, such as deforestation, to a way of reducing it.

Check your knowledge

A mix of recall, explanation and application questions. Attempt them, then check against the solutions.

1. Explain what an arrow in a food chain represents. (1 mark)
2. Explain why food chains are usually short. (2 marks)
3. Name two processes that return carbon dioxide to the air. (2 marks)
4. State one effect of human activity on the environment and one way to reduce it. (2 marks)