Photosynthesis
The process by which green plants convert sunlight, water, and carbon dioxide into food and oxygen.
Overview
Photosynthesis is a chemical process used by plants, algae, and some bacteria to capture energy from sunlight and store it as chemical energy in sugars. It is the foundation of nearly every food chain on Earth and the source of the oxygen we breathe.
The equation
The overall reaction takes six molecules of carbon dioxide and six of water, and — powered by light — produces one molecule of glucose and six molecules of oxygen. Plants absorb light using chlorophyll, the green pigment found in chloroplasts.
Light and dark reactions
Photosynthesis has two stages. The light-dependent reactions capture sunlight and split water, releasing oxygen. The light-independent reactions, called the Calvin cycle, use that stored energy to build sugars from carbon dioxide.
Why it matters
Beyond feeding plants, photosynthesis regulates atmospheric oxygen and removes carbon dioxide, making it central to climate and life as we know it.