Organisms incapable of utilizing CO2 (inorganic carbon) as the sole source of carbon and obtain water, minerals and organic compounds from other organisms are called heterotrophs and the mode of nutrition as heterotrophic nutrition. Mode of nutrition where source of carbon is organic and energy used is solar energy is called photoheterotrophic nutrition (e.g. in case of purple non-sulphur bacteria) and the mode where source of carbon is organic and energy used in chemical energy, it is called chemoheterotrophic nutrition (e.g. in parasites and mutualists). It includes parasitic, saprophytic, symbiotic and insectivorous types of nutrition.