In the food chain, heterotrophs are secondary and tertiary consumers. Carbon fixation is the process of converting inorganic carbon (CO2) into organic compounds such as carbohydrates, usually by photosynthesis. Organisms, which can use carbon fixation to manufacture their own nutrition, are called autotrophs. read more
Heterotrophs may be subdivided according to their energy source. If the heterotroph uses chemical energy, it is a chemoheterotroph (e.g., humans and mushrooms). If it uses light for energy, then it is a photoheterotroph (e.g., green non-sulfur bacteria). read more
Heterotrophs that depend on autotrophs and other heterotrophs for their energy level are placed next on the food chain. Herbivores that feed on autotrophs are placed in the second trophic level. Carnivores that eat meat and omnivores that eat all types of organisms are placed next in the trophic level. read more