All organisms respire in order to release energy to fuel their living processes. The respiration can be aerobic, which uses glucose and oxygen, or anaerobic which uses only glucose. Because this process occurs in all life, we call it a universal chemical process.
Respiration releases energy - it is an exothermic process. This means it releases heat energy.
Photosynthesis is the process by which plants, and some bacteria, synthesise food molecules which they then use, in addition to other things, for respiration. The process of photosynthesis requires energy – it is endothermic.
Don't confuse respiration with breathing, which is ventilation. Respiration happens in mitochondria within cells.
Every cell in a living organism requires energy to live. This energy is released during cellular respiration in the form of ATP and is used:
Respiration is only around 40 per cent efficient. As animals respire, heat is also released. In birds and mammals, this heat is distributed around the body by the blood. It keeps these animals warm and helps to keep a constant internal temperature.
Energy is also used: