Photosynthesis, the conversion of light to energy in plant cells, requires sunlight to properly function. As the sunlight enters the plant's cell, it is absorbed by chlorophyll, a green pigment contained within the cell.
Electrons from hydrogen atoms in water molecules are attracted to the chlorophyll, causing the water molecules to break apart into oxygen molecules, protons, electrons and atoms. The oxygen molecules pair up and are released into the atmosphere, while the electrons and protons produce a chemical reaction in the cell.
Photosynthesis is necessary for life, as the energy contained in the plant is passed on to animals who eat the plant.