Photosynthesis is the process plants undergo to make energy. Carbon dioxide + water > oxygen and glucose. Plants need sunlight for this process to occur. The roots of the plant take water from the soil and the leaves collect carbon dioxide from the air for photosynthesis to happen. The oxygen is then released into the air and the plant uses the glucose for nutrients to grow. Plants need to be in a correct temperature too, so that they can photosynthesise effectively.