The Carbon cycle
Whole cycle is powered by photosynthesis .
CO2 is removed from the atmosphere by green plants and algae and the carbon is used to make carbohydrates, fats and proteins which makes the body of plants and algae.
Some of the carbon is returned to the atmosphere as CO2 when the plants and algae respire. Some of the carbon becomes part of the fats and proteins in animals when the plants and algae are eaten. The carbon then moves through the food chain.
Some of the Carbon is returned to the atmosphere as CO2 when th animals respire.
When plants, animals and algae die, other orgainsms will eat their remains. When these orgainsms respire, CO2 is returned to the atmosphere.
Animals also produce waste, and this is also broken down by other animals and microorgainsms. Compounds in the waste are taken up from the soil by plants as nutrients- they are put back into the food chain again.
Some useful plants and animal products e.g. wood and fossil fuels are burnt (combustion). This also releases CO2 back into the air.