co2 is removed from the air in photosynthesis by green plants and algae (carbon makes carbohydrates, proteins and fats which are eaten and carbon moves up the food chain)
co2 is returned to the air when plants, algae and animals respire. decomposers respire while they return mineral ions to the soil
co2 is returned to the air when wood and fossil fuels are burnt (combustion) as they contain carbon from photosynthesis
what is the water cycle
sun's energy causes water to evaporate from the sea/ lakes, forming water vapour
water vapour can also be formed as a result of transpiration in plants
water vapour rises and then condenses to form clouds
water is returned to land by precipitation (rain, snow or hail) and this runs to lakes to provide water for plants and animals
