What is the biogeochemical cycle? The elements of the global ecosystem, including the food chain, respiration, and photosynthesis, are all part of a worldwide cycle known as the biogeochemical cycle. light photosynthesis respiration eating carbon from the starch of potatoes (c) carbon used as fuel and raw material for the body When one organism, like a bear, eats another organism, such as a fish, the material that made up the fish becomes part of the bear. A very important substance in this transfer is carbon (C). Look at the diagram above. If Kumi eats a potato, the carbon from that potato enters her body. And when I breathe, the carbon that was inside my body becomes carbon dioxide (CO 2 ) and is expelled from my body. That's right! Then the carbon that left your body is captured by plants through photosynthesis and is transformed into the carbon that makes up starch (which is a type of saccharide). Then that potato is eaten by Kumi (or a cow or some other hungry creature), and the carbon is returned once more to the body of an animal. Photosynthesis and respiration 43