Edexcel A Level (IAL) Biology -4.15 The Variety of Life- Study Notes- New Syllabus
Edexcel A Level (IAL) Biology -4.15 The Variety of Life- Study Notes- New syllabus
Edexcel A Level (IAL) Biology -4.15 The Variety of Life- Study Notes -Edexcel A level Biology – per latest Syllabus.
Key Concepts:
- 4.15 know that, over time, the variety of life has become extensive but is now being threatened by human activity
Variety of Life & Human Threats to Biodiversity
🌱 Introduction
Over billions of years, life on Earth has evolved into an incredible variety of species, each adapted to different environments. This biodiversity is the result of evolution, natural selection, and speciation but in recent centuries, human activities have started to threaten it on a global scale.
🌍 The Growth of Life’s Variety Over Time
Early Earth:
- Life began as simple prokaryotic cells (bacteria-like).
- Over millions of years → evolution produced multicellular organisms, plants, animals, and complex ecosystems.
Evolutionary processes such as mutation, natural selection, and genetic drift led to the formation of millions of species.
Today’s biodiversity:
- Estimated 8-10 million species on Earth.
- Found in every habitat – from deep oceans to tropical forests.
- Each species plays a role in maintaining ecosystem balance.
⚠️ The Threat – Human Impact on Biodiversity
Human activity in the last few centuries has caused rapid loss of species and habitats, much faster than natural extinction rates.
Major Human Threats:
| Human Activity | How It Reduces Biodiversity | Example |
|---|---|---|
| Deforestation | Destroys habitats and disrupts food chains | Amazon rainforest clearance |
| Pollution | Contaminates air, soil, and water → harms organisms | Oil spills, plastic waste, acid rain |
| Climate Change | Alters temperature and rainfall → species lose suitable habitats | Coral bleaching, polar ice loss |
| Overexploitation | Overfishing, hunting, logging → species decline | Bluefin tuna, rhinos |
| Urbanisation & Agriculture | Converts wild habitats into farmland/cities | Wetland drainage, monoculture crops |
| Introduction of Invasive Species | Non-native species outcompete local ones | Grey squirrels in UK replacing red squirrels |
🌱 Why This Matters
- Loss of biodiversity weakens ecosystem stability.
- Reduces genetic variation, limiting species’ ability to adapt to change.
- Affects human survival, since biodiversity provides:
- Food
- Medicine
- Clean air & water
- Climate regulation
Key Idea:
Biodiversity is essential for a balanced and sustainable planet – protecting it is not optional, but vital.
🧩 Conservation Efforts (Brief Mention)
- Establishing protected areas (national parks, wildlife reserves).
- Captive breeding and seed banks to preserve species.
- International agreements (e.g., CITES, Paris Climate Accord).
- Education & research to promote sustainable use of resources.
📊 Summary Table
| Concept | Description | Key Point |
|---|---|---|
| Biodiversity | Variety of all living species and ecosystems | Product of evolution |
| Natural evolution | Gradual increase in life’s variety | Driven by genetic change & adaptation |
| Human threats | Activities reducing biodiversity | Deforestation, pollution, etc. |
| Effect | Species extinction, ecosystem imbalance | Reduced stability & resources |
| Conservation | Human efforts to protect biodiversity | Vital for future sustainability |
⚡ Quick Recap
Life’s variety evolved naturally over millions of years.
Humans are now the main cause of biodiversity loss.
Major threats → deforestation, climate change, pollution, overexploitation.
Consequences → habitat loss, species extinction, unstable ecosystems.
Solution → conservation, sustainable development, and awareness.