Photosynthesis is the process in plants and some algae that converts light energy into chemical energy, stored in bonds. The overall reaction is: 6CO2 + 6H2O (+ light energy) → C6H12O6 + 6O2To make sugar plants need light energy, carbon dioxide and water. The products are also water, oxygen in the air and carbohydrates. This is the main source of O2 that humans breathe, and therefore deforestation is a significant concern today. Photosynthesis occurs in chloroplasts, using chlorophyll, the green pigment. It occurs in the leaves of plants and little in the stems. The plant leaf is made up of the upper and lower epidermis, mesophyll, stomata and veins. Epidermal cells do not contain chloroplasts, so photosynthesis does not occur. They protect the rest of the leaf. The stomata are small holes, located in the lower part of the epidermis and serve for the exchange of air, CO2 enters and O2 exits. Mesophyll cells have chloroplasts and photosynthesis occurs there. The chloroplast includes the outer and inner membranes, the stroma, the thylakoids of the grana and the intermem...