Why is any organism an open system?

Biological organisms are open systems. Energy is exchanged between them and their surroundings as they consume energy-efficient molecules and release energy to the environment while doing work. Like everything in the physical world, energy obeys the laws of physics. The laws of thermodynamics govern the transfer of energy within and among all systems in the universe. When studying energy, scientists use the term “system” to refer to matter and the environment associated with the transfer of energy. Everything outside the system is called the environment. Individual cells represent biological systems.