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The biosphere is the thin layer of the Earth where life exists — stretching from the deepest ocean trenches to the highest mountaintops. It includes all living organisms and the environments they inhabit. For the Edexcel B specification, you need to understand that the biosphere provides essential goods (tangible resources we can harvest) and services (processes that support life on Earth). Without the biosphere, human civilisation simply could not exist.
The biosphere is the zone of life on Earth. It extends from approximately 11 km below sea level (the Mariana Trench) to around 9 km above sea level (the summit of Everest), although most life is concentrated in a much narrower band — from the ocean surface to a few hundred metres above and below.
The biosphere interacts with three other Earth systems:
| System | Description | Interaction with Biosphere |
|---|---|---|
| Atmosphere | The layer of gases surrounding the Earth | Plants absorb CO₂ and release O₂ through photosynthesis |
| Hydrosphere | All water on Earth (oceans, rivers, ice, groundwater) | Water sustains all life; the water cycle distributes freshwater |
| Lithosphere | The rocky outer layer of the Earth (crust and upper mantle) | Weathering of rocks releases minerals; soil supports plant growth |
graph TD
B["BIOSPHERE<br/>All living organisms"] --> A["ATMOSPHERE<br/>Gases — O₂, CO₂, N₂"]
B --> H["HYDROSPHERE<br/>Water — oceans, rivers, ice"]
B --> L["LITHOSPHERE<br/>Rock and soil"]
A -->|"CO₂ for photosynthesis<br/>O₂ for respiration"| B
H -->|"Water for life<br/>Nutrient transport"| B
L -->|"Minerals and nutrients<br/>Soil for roots"| B
Goods are tangible, physical resources that humans obtain directly from the biosphere. They are sometimes called provisioning services.
The biosphere provides all of our food, whether from farming, fishing, hunting or gathering. Globally, agriculture uses approximately 38% of the world's land surface. Different biomes support different types of food production:
Exam Tip: When discussing food from the biosphere, give specific examples tied to specific biomes. Saying "the Amazon provides indigenous communities with fish, fruits such as açaí berries, and Brazil nuts" is far more effective than simply saying "rainforests provide food."
Forests cover approximately 31% of the world's land area (around 4.06 billion hectares) and provide:
The global timber industry is worth over $600 billion per year and employs tens of millions of people, particularly in countries like Canada, Russia, Brazil, Indonesia and Sweden.
An estimated 25% of all modern medicines are derived from plants, and many more are based on compounds first discovered in natural ecosystems:
| Medicine | Source | Biome |
|---|---|---|
| Aspirin | Willow bark (Salix species) | Temperate deciduous forest |
| Quinine | Cinchona tree bark | Tropical rainforest |
| Morphine | Opium poppy (Papaver somniferum) | Temperate grassland/farmland |
| Taxol | Pacific yew tree (Taxus brevifolia) | Temperate coniferous forest |
| Curare | Various tropical vines | Tropical rainforest |
| Vincristine | Rosy periwinkle (Catharanthus roseus) | Tropical forest (Madagascar) |
The rosy periwinkle from Madagascar provides vincristine, used to treat childhood leukaemia, increasing survival rates from 20% to over 80%. This single example illustrates why biodiversity loss in tropical rainforests could mean the loss of undiscovered medicines.
Services are the processes that the biosphere carries out which benefit humans indirectly. These are sometimes called ecosystem services and they are arguably even more valuable than goods because they are difficult or impossible to replace with technology.
The biosphere plays a critical role in regulating the Earth's climate:
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