Plants, along with certain bacteria and algae, perform photosynthesis to produce two vital compounds for life: glucose and oxygen. This process transforms light energy into chemical energy, sustaining ecosystems and human existence alike.
The overall reaction can be summarized as:
6 H₂O + 6 CO₂ → C₆H₁₂O₆ + 6 O₂
Thus, six molecules of water and six molecules of carbon dioxide yield one molecule of glucose and six molecules of oxygen.
In the chloroplasts, chlorophyll pigments absorb sunlight, exciting electrons to a higher energy state. These electrons travel through a chain that produces adenosine triphosphate (ATP) and nicotinamide adenine dinucleotide phosphate (NADPH). Simultaneously, water molecules split (photolysis), releasing oxygen into the atmosphere.
ATP and NADPH generated above power the Calvin cycle, where CO₂ is fixed into sugars. Carbon dioxide binds to ribulose‑1,5‑bisphosphate, ultimately forming glucose. For every six CO₂ molecules incorporated, one glucose molecule emerges.
Photophosphorylation refers to the light‑driven creation of NADPH. Chlorophyll A and B are essential for harvesting light; they enable electron excitation, water splitting, and the subsequent synthesis of energy carriers used in carbon fixation.
Photosynthesis converts water and carbon dioxide into glucose and oxygen through two stages: light‑dependent reactions that generate ATP and NADPH, and the Calvin cycle that fixes carbon into sugars. This elegant biochemical machinery sustains life on Earth.
