What is necessary for photosynthesis to occur?

Essentially, photosynthesis is the process by which plants convert light energy to produce sugar. It needs water, light and carbon dioxide to occur and produces oxygen and sugar/carbohydrates. Photosynthesis is a two step process; light dependant reactions and light independent reactions. The first step uses water and light, produces energy in the form of ATP and releases oxygen as a waste product. The light is captured within a pigment called chlorophyll which is responsible for the green colour of plants and is present within chloroplasts in the cell.The second step takes carbon dioxide and puts it through what is called the Calvin-Benson Cycle. This uses the ATP from step one to add and remove carbons to the Carbon dioxide to make the desired sugars.