membranes have three primary functions 1) they keep toxic substances out of the cell 2) they contain receptors and channels that allow specific molecules, such as ions, nutrients, wastes, and metabolic products, that mediate cellular and extracellular activities to pass between organelles and between the cell and the outside environment and 3) they separate vital but incompatible metabolic processes conducted within organelles.
Plants are producers and make their own food through a process of photosynthesis. Organisms are classified into domains according to shared characteristics.
