carbon cycle

• • when organisms die, they decay
  • this is because they are digested by microorganisms especially in warm, aerobic conditions
  • decay puts nutrients (e.g mineral ions) and complex compounds (e.g protein and fats) back into the soil
• • plants turn elements like carbon, oxygen, hydrogen and nitrogen from soil into carbohydrates, proteins and fats
  • these get passed up the food chain
  • they return to the environment through waste products
• 1. carbon dioxide removed from air by plants during photosynthesis, carbon used to make glucose
  2. glucose is turned into carbohydrates, proteins and fats
  3. when plants respire, carbon returned to atmosphere as carbon dioxide
  4. plants eaten by animals, carbon becomes part of fat and protein in animal and moves up food chain
  5. when plants and animals die, detritus feeders and microorganisms digest remains, they respire and carbon dioxide returned to atmosphere
• • animals produce waste that is digested by detritus feeders and microorganisms
  • this returns carbon as carbon dioxide into atmosphere
• • burning wood and fossil fuels releases carbon dioxide back into atmosphere