carbon cycle

• living things are made out of materials they take from the world around them
• plants turn elements like carbon, oxygen, hydrogen and nitrogen from the soil and air into complex compounds that make up living organisms
• materials decay because they're broken down by microorganisms
• decay puts the things plants need to grow back into the soil
• firstly, carbon dioxide is removed from the atmosphere by green plants and algae during photosynthesis. the carbon is used to make glucose
• when plants and algae respire, some carbon is returned to the atmosphere as carbon dioxide
• when plants and algae are eaten by animals, some carbon becomes part of fats and proteins in their bodies
• when animals respire, carbon is returned to the atmosphere as carbon dioxide
• when plants, algae and animals die, other animals and microorganisms feed on their remains
• animals produce waste that is broken down by detritus feeders
• the combustion of wood and fossil fuels releases carbon dioxide back into the air
• carbon is constantly being cycled from the air, through food chains and eventually back out into the air again