The theory must fit in with other accepted theories. Elements are the simplest type of a substance. Living things carry out certain functions which are called life processes. A food chain is really just one of many paths through a food web. Food chains are used for land ecosystems and food webs for ocean ecosystems.
Food chains show just consumers, but food webs also show producers.
Food chains always end with decomposers, but food webs never do. Our solar system consists of many different types of objects. Animal and plant resources are now being lost through the extinction of species.