Chloroplast where photosynthesis takes place.

Chloroplast: cutaway illustration of a chloroplast, the organelle in plant cells where photosynthesis occurs. During photosynthesis, solar energy is captured by pigments (which gives chloroplasts their green colour) and is made available to the plant via energy changes in electrons and by proton pumping. These electrons and protons come from the hydrogen present water. Thus photosynthesis splits water molecules and evolves oxygen (which is released into the atmosphere).