The things required for photosynthesis are chlorophyll, sunlight, water and carbon dioxide. Chlorophyll, which absorbs light energy, is present in chloroplasts in the leaves. Plants take atmospheric carbon dioxide through their openings called stomata on the underside of the leaves. Each stoma has two guard cells that swell and move away to open the stoma. The root system of the plants absorbs water from the soil, which reaches the leaves through xylem.