amazon.co.ukEcology and Ecosystems
A-Level Biology revision: Ecology and Ecosystems. Learning objectives, key points, worked examples and practice questions across AQA, Edexcel, OCR, WJEC and CCEA.
📌 Key Points
Key Fact: GPP = total photosynthesis; NPP = GPP - R (respiration); Efficiency = energy transferred/total available x100% (typically 10%); Pyramids: energy always upright; biomass can be inverted
Key Fact: Carbon: photosynthesis, respiration, combustion, decomposition, ocean uptake; Nitrogen: fixation (lightning, bacteria), nitrification (ammonia->nitrite->nitrate), assimilation, denitrification
Key Fact: Growth curves: lag, log, stationary, death; Carrying capacity K; r/K selection; Predator-prey: Lotka-Volterra cycles
Key Fact: Succession: pioneer -> intermediate -> climax; each stage modifies environment for next; Deflected succession: human interference
Key Fact: Climate change: greenhouse effect, CO₂, CH₄; Eutrophication: nitrates/phosphates -> algal bloom -> decomposition -> O₂ depletion -> dead zones
🎯 Learning Objectives
- Describe energy flow: productivity (GPP, NPP), ecological efficiency, pyramids of number/biomass/energy
- Explain carbon and nitrogen cycles in detail
- Understand population dynamics: growth curves, limiting factors, predator-prey cycles
- Explain succession: primary vs secondary, climax community
- Understand human impacts: climate change, eutrophication, conservation
💡 Worked Example
Exam-Style Question
Question: Explain why only ~10% of energy transfers between trophic levels
Model Answer:
Energy lost as: heat (respiration), faeces (undigested), urine (excretion), uneaten parts. Only energy in consumed biomass available to next level. 2nd law of thermodynamics: entropy increases
❓ Practice Questions
Model answers are being added progressively - questions marked ✗ don't have one yet. Cross-check with your teacher or the official mark scheme.
Questions:
- Define GPP and NPP✗ answer coming soon
- Describe nitrogen fixation✗ answer coming soon
- Draw logistic growth curve, label K and r✗ answer coming soon
- What is a climax community?✗ answer coming soon
- Explain ocean acidification mechanism✗ answer coming soon
🎬 Video Resources
- Ecology and Ecosystems - Overview -- YouTube Search
- Ecology and Ecosystems - Exam Questions -- YouTube Search
📄 Past Papers & Exam Resources
🔗 Further Reading & Resources
- Physics & Maths Tutor - Ecology and Ecosystems -- Free notes, worksheets, and past paper questions by topic
- Dr Frost Maths - Ecology and Ecosystems -- Free resources, slides, and interactive questions
- BBC Bitesize - Ecology and Ecosystems -- BBC Bitesize revision resources