Sometimes you mix different substances and you don't make new substances but mostly of the time you do make new substances , so the answer is chemical change.
The endoplasmic reticulum aids in the production and movement of proteins and other materials through the cell.
In a closed ecological system, any waste products produced by one species must be used by at least one other species. If the purpose is to maintain a life form, such as a mouse or a human, waste products such as carbon dioxide, feces and urine must eventually be converted into oxygen, food, and water.
cell walls, chloroplasts, large central vacuole, plastids,
It depends on which forms they come in.
