1. what is the basic unit of organization of all living things? 2. what is the difference between an organ and an organ system? 3. for your organ system, describe how the system works at the organ level. 4. for your organ system, describe how the system works at the tissue level. 5. describe what would happen if an organ in your specific organ system stopped working. level 1: organ system  level 2: organ  level 3: tissues of the system