What process do trees use to convert light energy into chemical energy?

Trees use photosynthesis to convert light energy into chemical energy. In green plant cells, chlorophyll captures light inside chloroplasts, helping transform water and carbon dioxide into energy-rich sugars.

The process has two linked stages. Light-dependent reactions split water, release oxygen, and produce ATP and NADPH. The Calvin cycle then uses those energy-rich molecules to build carbohydrates from carbon dioxide. Trees use these sugars for growth, respiration, and making materials such as cellulose.

Photosynthesis is not simply “plant breathing.” Respiration breaks down sugars to release usable energy, while photosynthesis stores light energy in chemical bonds. Leaves usually perform most photosynthesis, although green stems and other tissues can contribute.

The oxygen released by photosynthesis comes primarily from split water molecules, not from carbon dioxide. This process also makes plants major contributors to Earth’s oxygen cycle and the foundation of most terrestrial food webs.