A sequence of organisms,each of which sevres as a source of food for the next,is called a food chain. It determines how chemical energy and nutrients move from one organisms to another and return their nutrients to the soil for by producers through the trophic levels in an ecosystem along the same pathways-primary through photosynthesis,feeding, and most organisms are eaten ny more than one type of consumer. Because of this, organism in most ecosystems from a complex network of interconnected food chains called a food web.