Photosynthesis is the process where plants make their own food from sunlight. Most plants are able to make food directly from light energy, for example the Sun, instead of eating other organisms or relying on nutrients. Photosynthesis can happen in plants because they have chlorophyll.Chlorophyll is the pigment that makes plants green. Chlorophyll captures the Sun’s energy and uses it to make sugars out of carbon dioxide from the air and water. The sugars fuel a plant's roots, stems, and leaves so the plant can grow.After plants use the Sun's light to make their food, plants release oxygen into the air. This oxygen is very helpful because humans and animals need it to breathe.he sugars fuel a plant's roots, stems, and leaves so the plant can grow. After plants use the Sun's light to make their food, plants release oxygen into the air. This oxygen is very helpful because humans and animals need it to breathe.