2. Let's Talk Photosynthesis The importance of plants At the base of the ecosystem, plants, algae, and some bacteria supply food to all living crea- tures. The majority of them use a process called photosynthesis, in which saccharides and oxygen (O 2 ) are created from carbon dioxide by splitting atoms of water, using energy from the Sun. Saccharides are also known as carbohydrates and are vital to living creatures like us. sunlight photo- synthesis saccharides = carbohydrates