Didactic illustration representing vegetable nutrition. At night (left part), the stomata being closed, the plant absorbs O2 and releases CO2. The day (right part), when the leaf stomata are open, the leaves take CO2 from the air, water and minerals are taken from the roots in the soil. During photosynthesis, the plant cell and especially the chloroplasts, thanks to the light energy, produce organic matter as well as oxygen from absorbed mineral salts, water and CO2..The plant cell also stores toxic materials in vacuoles, or cell walls.