Ecology and human influences

Learning objectives

• Trace food webs and nutrient cycles.
• Explain population limiting factors.
• Evaluate conservation and human impacts.

The big idea

Food webs connect producers, consumers and decomposers. Carbon and nitrogen cycle through organisms and their environment; population growth depends on resources, disease, predation and competition.

Habitat loss, pollution, climate change and overharvesting can reduce biodiversity. Eutrophication links nutrient enrichment with increased growth, decomposition and oxygen depletion. Conservation decisions combine ecological evidence with social needs rather than treating every intervention as equally effective.

Investigate and explain

Using the worked example as supplied data, predict the effect of changing one condition. Draw a labelled model, record your reasoning and identify a variable that would need controlling. No human, animal or microbial experiment is required.

No exact PhET model is claimed for this topic. Use diagrams and supplied-data reasoning instead.

Open the interactive investigation

Check your understanding