To grow and eat, plants use energy from the sun. This is photosynthesis. Four conditions are necessary for this phenomenon: the presence of chlorophyll, carbon dioxide, water carried by the roots and the sun. Thanks to the energy of the sun, the water and CO2 inside the plant are broken down. This results in the production of carbohydrates which will provide the plant with the energy it needs to develop but also with the oxygen that the plant will reject into the atmosphere. Photo credit : Ben