Autotrophic organisms: organisms that can synthesize their own organic matter from inorganic substances belong to autotrophs. Such as cyanobacteria, nitrifying bacteria and green plants.
Heterotrophs: Organisms that can only ingest ready-made organic matter from outside belong to heterotrophs. Such as most animals and fungi.
Generally speaking, digestion is a typical example of assimilation. The same is true of photosynthesis, because in this process, plants use carbon dioxide and sunlight to make their own food (organic molecules) and store these organic molecules in the plants themselves.
Generally speaking, all higher plants and some lower plants, and a small number of bacteria (nitrifying bacteria) can carry out photosynthesis.
Error correction: Nitrifying bacteria can't carry out photosynthesis. It oxidizes ammonia in soil into nitrous acid, and then oxidizes nitrous acid into nitric acid. Nitrifying bacteria can use the chemical energy released by these two chemical reactions to hydrate carbon dioxide and water into sugars for nitrifying bacteria to maintain their own life activities. (See "The Compulsory Course of Biology in Senior High School-Molecules and Cells", People's Education Press, 2nd edition, February, 2007) The magma melts the surrounding rock and makes it a part of the magma, which is called assimilation.