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4.4Ecology and the Environment

Human influences on the environment — Edexcel Modular - OL Revision Notes & Topical Questions

5 min read 7 parts Lesson 5 of 5 2 quizzes

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Lesson summary

Human influences on the environment Edexcel O Level Modular Biology notes: understand the biological consequences of pollution of air by sulfur dioxide and carbon monoxideBiodiversity makes ecosystems more stable.Bioaccumulation concentrates toxins up food chains.Ozone depletion …

  • Human influences on the environment Edexcel O Level Modular Biology: what to do next
  • Deforestation
  • Global warming
  • Invasive species
  • Sustainability
  • Conservation

Part 1 of 6Key ideas

Key ideas
Biodiversity makes ecosystems more stable.
Bioaccumulation concentrates toxins up food chains.
Ozone depletion by CFCs increases UV.

Part 2 of 6Syllabus points

1
understand the biological consequences of pollution of air by sulfur dioxide and carbon monoxide
2
understand that water vapour, carbon dioxide, nitrous oxide, methane and CFCs are greenhouse gases
3
understand how human activities contribute to greenhouse gases
4
understand how an increase in greenhouse gases results in an enhanced greenhouse effect and that this may lead to global warming and its consequences
5
understand the biological consequences of pollution of water by sewage
6
understand the biological consequences of eutrophication caused by leached minerals from fertiliser

Part 3 of 6Process & sequence

  • Fertiliser run-off
  • Algal bloom
  • Algae die
  • Bacteria decompose (use O₂)
  • Fish die
Conservation
National parks
Seed banks
Captive breeding
Laws and quotas

Part 4 of 6Summary

Summary
Loss of oxygen in water from nutrients is eutrophication.
CO₂ causes global warming.

Part 5 of 6Keep going

Human influences on the environment Edexcel O Level Modular Biology: what to do next

These Human influences on the environment Edexcel O Level Modular Biology notes covered the key ideas, worked examples and exam technique for this topic. Check your Human influences on the environment Edexcel O Level Modular Biology understanding with the practice questions below, then reread any Human influences on the environment Edexcel O Level Modular Biology point you were unsure about before moving on.

1
Practice: Human influences on the environment Edexcel O Level Modular Biology practice questions
2
Previous lesson: 4.3 Cycles within ecosystems — Notes
3
Next lesson: 5.1 Food production — Notes
4
Course: Edexcel Modular - OL — all units
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Official syllabus: Pearson Edexcel International GCSEs

Human influences on the environment Edexcel O Level Modular Biology revision notes

Part 6 of 6Compare: Compare

Human impacts
ImpactCauseEffectOrganisms affectedSolutionExample
Global warmingCO₂, methaneRising temperature, sea levelCoral, polar speciesRenewable energyArctic ice melting
DeforestationFarming, loggingHabitat loss, CO₂ riseRainforest speciesReforestation, protected areasAmazon
Water pollutionFertiliser, sewageEutrophicationFishTreat sewage, reduce fertiliserAlgal blooms
Air pollutionBurning fuelsAcid rain, smogTrees, lichensCatalytic converters—
OverfishingDemand for fishPopulation collapseCodQuotasNorth Sea cod
Invasive speciesHuman transportNatives outcompetedNative wildlifeControl, biosecurityCane toad

Key terms

Command terms

Command terms
Give / State / Name
Recall a fact; one idea per mark.
Define
Give the exact meaning using the specification keywords.
Describe
Give an account of what happens / the pattern in data, quoting values; no reasons needed.
Explain
Give reasons with linked statements (cause → effect). Each linked step is usually a separate marking point.
Suggest
Use knowledge in a new context; more than one answer may be accepted.
Compare
Similarities and differences; each point must refer to both items.
Calculate
Show working; include units; check significant figures. Method marks are given even if the final answer is wrong.
Discuss
Explore the issue from different angles and link the points.
Evaluate / Assess
Weigh strengths and weaknesses and reach a supported judgement.
Deduce
Draw a conclusion from the information given.
Justify
Support a statement/choice with evidence.

Exam technique

Keywords the mark scheme looks for in this lesson

Keywords the mark scheme looks for in this lesson
Biodiversity · Deforestation · Global warming · Pollution · Invasive species · Sustainability · Conservation · Eutrophication
Learn each definition in the Key words tab exactly; a missing keyword in a definition usually loses the mark.

How to get full marks (examiner guidance)

How to get full marks (examiner guidance)
Use specification keywords exactly (e.g. eukaryotic/prokaryotic, enzyme–substrate complex, active site, complementary).
Link ideas
Link ideas for “explain” each marking point is usually a cause → consequence step; unlinked facts often score nothing.
Use the information in the question
“discuss/evaluate” answers must use the data provided and match the number of marks.
Convert units carefully (mg → g, cm³ → dm³) and show working for calculations.
Avoid vague words
“it”, “stuff”, “things”, “goes up”, “energy is made”. Name the substance and the process.
Do not extrapolate a graph line beyond the data or to zero unless asked.
Six-mark extended responses are marked on content AND a logical, linked line of reasoning.

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