During photosynthesis, plants convert light energy, usually from the sun, into chemical energy stored in glucose. This process occurs primarily in the chloroplasts of plant cells, using carbon dioxide from the air and water from the soil. While glucose is a critical product that provides energy for the plant itself, the essential substance released into the atmosphere as a byproduct is oxygen.
Oxygen is produced when water molecules are split during the light-dependent reactions of photosynthesis. This oxygen is then released into the air, where it becomes crucial for the survival of aerobic organisms, including humans. Humans and other animals rely on oxygen for cellular respiration, a process that converts the energy in food into a form that cells can use. Therefore, the release of oxygen during photosynthesis is vital for maintaining the balance of gases in the atmosphere and supporting life on Earth.