The basic model for a food chain is that a green plant is consumed by an herbivore that is then eaten by a predator . A simple example of a food chain is an aquatic plant gets eaten by a tadpole that gets eaten by a Northern pike that is consumed by an otter. Food chains become complex with animals at different stages of development consuming different types of prey. For example, a young pike may be food for a large perch but a large pike will eat full-grown perch. Perhaps a better way to describe food chains is to call them food webs .
Plants have the remarkable ability to make their own food.
For this reason they are called primary producers . The results from all of these factors are oxygen and the carbon containing organic compounds that feed the plants. The plant's productivity depends on the availability of CO2, sunlight, and water. Plants convert the carbon dioxide that we exhale out of our lungs into oxygen which is the main component of air that we rely on to breathe. Without plants than there would be no source of oxygen or food source and life on Earth would stop.