Photosynthesis

In short: In photosynthesis plants use light to build sugar from carbon dioxide and water and release oxygen. It is the foundation of almost all food chains.

In more detail: The reaction takes place in the chloroplasts, where the green pigment chlorophyll absorbs light energy.

In detail

• Overall equation: 6 CO₂ + 6 H₂O + light → C₆H₁₂O₆ + 6 O₂.
• Light reaction and Calvin cycle: First light energy is converted into chemical energy, then sugar is built from it.
• Leaf green: Chlorophyll reflects green, so leaves look green. In autumn it is broken down.
• Oxygen: Algae and plants supply a large share of the oxygen in the atmosphere.
• Carbon sink: Forests and oceans bind CO₂ and so slow climate change (kohlenstoffkreislauf).