Puzzle solved Over the next two centuries scientists continued to develop their knowledge of this process. They found that chlorophyll is needed for a reaction to occur and that this is contained in chloroplasts, found mainly in leaves. Carbon dioxide is absorbed by the leaves and this reacts with water to produce glucose and oxygen. Sunlight is needed for the reaction to occur. The term ‘photosynthesis’ (light-making) was introduced in 1893 by Charles Barnes.