Human Influences on the EnvironmentEdexcel GCSE Biology: Revision notes

Section 1

Human Interactions in Ecosystems

Human activity affects biodiversity positively (conservation, reforestation) and negatively (habitat destruction, pollution, invasive species).

Key termsbiodiversityconservation

Exam tip

Evaluate questions need both a benefit and a drawback.

Section 2

Fish Farming

Positive: reduces wild stock pressure. Negative: waste causes eutrophication; escaped fish spread disease/interbreed.

Key termsfish farming

Example

Farmed salmon can transmit sea lice to wild salmon.

Section 3

Non-Indigenous Species

Species introduced where not native; can outcompete, prey on, or hybridise with native species, reducing biodiversity.

Key termsnon-indigenous species

Common mistake

Not automatically 'bad' — the key point is ecosystem disruption.

Section 4

Eutrophication

Excess nutrients → algal bloom → light blocked → plants die → decomposers multiply → oxygen depletes → organisms die.

Key termseutrophicationalgal bloom

Exam tip

Learn the causal chain in order for exam marks.

Section 5

Benefits of Biodiversity

Stable food webs, genetic resources, ecosystem services. Conservation protects endangered species; reforestation restores habitats, reduces erosion, absorbs CO2.

Key termsreforestation

Think of it like this

Biodiversity is like a safety net of many threads — more species means more resilience.

Must Know

Fish farming: reduces wild fishing but causes eutrophication.
Non-indigenous species disrupt native populations.
Eutrophication: nutrients→bloom→light blocked→decay→O2 depletes→death.
Conservation/reforestation maintain biodiversity, restore habitats.

That's the notes covered.

Carry on to the next subtopic.