Ecology and Environment IGCSE Biology: Complete Guide

🌍 Understanding Ecology in IGCSE Biology

Ecology studies relationships between organisms and their environment. This guide covers ecosystems, food chains, and environmental issues.

🧠 Memory Tips

Trophic Levels: “Producers Primary Secondary Tertiary”

• Producers: Plants (make own food)
• Primary: Herbivores (eat plants)
• Secondary: Carnivores (eat herbivores)
• Tertiary: Top carnivores

Nutrient Cycles: “Carbon Nitrogen Water”

• Carbon cycle: CO₂ ↔ Organic compounds
• Nitrogen cycle: N₂ → Nitrates → Proteins
• Water cycle: Evaporation → Precipitation

📚 Key Concepts

Ecosystem Components

• Biotic factors: Living organisms
• Abiotic factors: Non-living (temperature, pH, light)
• Habitat: Where organism lives
• Niche: Role in ecosystem

Food Relationships

• Food chains: Linear feeding relationships
• Food webs: Interconnected food chains
• Energy flow: Unidirectional (10% rule)
• Biomass pyramids: Show mass at each level

Population Dynamics

• Population: Same species in area
• Community: All species in area
• Factors affecting population: Food, predators, disease, competition

Human Impact

• Deforestation: Habitat loss, climate change
• Pollution: Air, water, soil contamination
• Overfishing: Depletes fish stocks
• Climate change: Global warming effects

Conservation

• Protected areas: National parks, reserves
• Sustainable practices: Renewable resources
• Recycling: Reduce waste
• Alternative energy: Solar, wind power

🎯 Exam Focus

Common Questions:

1. Draw and explain food webs (6 marks)
2. Describe human environmental impact (8 marks)
3. Explain conservation methods (5 marks)
4. Analyze population graphs (4 marks)

Key Processes:

• Energy transfer through trophic levels
• Nutrient cycling in ecosystems
• Population growth and regulation

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