In the process a photosynthesis the carbon dioxide and the water react in the present of chlorophyll and sunlight to produce glucose, oxygen and water. The glucose and water are saved as energy inside the plant, and oxygen is evolved as a waste material. As we all know, that from any reaction some waste material is produced, so in the process of photosynthesis oxygen is that waste material, and through stomata plants do exchange of gases in which they absorb carbon dioxide which the useful gas and the release of oxygen which is the waste material produced during this process.