What gas do animals exhale and plants take in?

Carbon dioxide or CO2 is exhaled by animals when they use their food for energy. Oxygen is used to burn the glucose so that it can be used as energy for growth and repair. This is called cellular respiration and occurs in every single living organism. Plants then use the carbon dioxide to photosynthesise and create their own food in the form of glucose. They release oxygen and create water as a result of photosynthesis. Animals use the oxygen for cellular respiration and when the plants are consumed use the glucose for energy.