Autotrophic organisms produce their own food by converting inorganic materials to organic molecules, while heterotrophic organisms are unable to produce their own food. Heterotrophs rely on food that comes from other organisms.
Plants are autotrophs because they use photosynthesis to produce their own food. During photosynthesis, plants use energy from the sun to produce sugar. They use this sugar as a source of food. Some autotrophs produce food using a process called chemosynthesis. During this process, the organism makes food using energy produced by chemical reactions.
Most organisms are heterotrophs because they cannot produce their own food. This group of organisms includes all types of fungi and animals. Some bacteria are also classified as heterotrophs according to UCSB ScienceLine.