Understanding:
• The supply of inorganic nutrients is maintained by nutrient cycling
Nutrients refer to the material required by an organism, and include elements such as carbon, nitrogen and phosphorus
- The supply of inorganic nutrients on Earth is finite – new elements cannot simply be created and so are in limited supply
Hence chemical elements are constantly recycled after they are used:
- Autotrophs obtain inorganic nutrients from the air, water and soil and convert them into organic compounds
- Heterotrophs ingest these organic compounds and use them for growth and respiration, releasing inorganic byproducts
- When organisms die, saprotrophs decompose the remains and free inorganic materials into the soil
- The return of inorganic nutrients to the soil ensures the continual supply of raw materials for the autotrophs
Nutrient Cycling
