What does the word organism mean when talking about food chains?

When talking about food chains, an organism is considered to be anything from a plant which is an autotroph to a predator always a carnivore and it is called a heterotroph. A heterotroph is anything that does not produce its own food. Plants and trees, as well as flowers and cactuses make their own food without eating anything else. Instead, they go through a process called photosynthesis which requires a lot of carbon dioxide and water so they can make their own food. The scientific formula for this is CO2+H2O. When plants are done with photosynthesis, they go through another process called celluar respiration, which releases oxygen into our atmosphere for us to breathe. The scientific formula for this is CO2+H2O=C6+H12+O6+O2.