Assimilation (also called anabolism) refers to the process in which organisms convert nutrients obtained from the external environment into their own components and store energy. That is, organisms use energy to synthesize small molecules into large molecules.

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.

I hope it helps you.