1. Respiration-process by which plants release CO, while they break down the sugar
2. Animals eat plants- They break down sugars and starches by a process of metabolism and the products are energy water, and CO2 molecules.
3. Decomposition-when plants die, their parts (wood, leaves) decay bringing the carbon into the ground
4. Root respiration- respiration that occurs in roots, adds to soil respiration (the amount of CO2 produced through root respiration is determined by the root biomass ).
