Chloroplasts Chloroplasts serve as the site of photosynthesis. Leaves have about 500,000 chloroplasts per square millimeter of the surface. They are found primarily in cells of the mesophyll, green tissue of the leaf's interior. Each mesophyll cell contains 30-40 chloroplasts. They contain chlorophyll, the green pigment that absorbs energy from sunlight for use in photosynthesis, which means putting together with light.
Photosynthesis is the process by which plants make food.
In green plants, sunlight captured by chlorophyll enables carbon dioxide from the air to unite with water and minerals from the soil and create food. This process also releases oxygen into the air, and people and animals must have this oxygen to breathe. Energy from the sun splits water molecules into hydrogen and oxygen. The hydrogen joins with carbon from the carbon dioxide to produce sugar. Chlorophyll gives plants their color.