Digestion
Digestion is the process in which a living organism receives food from the outside environment, modifies it to transform it into nutrients, and selects assimilable or non-assimilable elements. By definition, digestion is a process present in all heterotrophic organisms. This digestion is carried out in a digestive system which can correspond to a simple digestive vacuole of a eubacterium, or to specialize as is the case of ruminant mammals. Digestion can also be defined as molecular simplification, ie the transformation of macromolecules into micromolecules.