All organisms are characterized by three processes. The sum if all chemical reactions taking place in an organism.
All organisms depend on external energy to fuel their chemical reactions.
They don t eat other organisms to sustain themselves. They also obtain energy from sunlight or few simple minerals to synthesize. They break down substances to release energy and make chemical building blocks for synthesizing other substances. Only works in a narrow range of internal physical and chemical conditions. Many of the organisms mechanisms serve to maintain internal consistency when external changes are great.