Photosynthesis — O/L Science

Photosynthesis is the process by which green plants (and algae) convert light energy into chemical energy stored as glucose. It occurs in chloroplasts, which contain the green pigment chlorophyll that absorbs sunlight, especially red and blue wavelengths.

The overall equation: 6CO₂ + 6H₂O + light energy → C₆H₁₂O₆ + 6O₂. Carbon dioxide from the air enters through stomata; water is absorbed from roots. Oxygen is released as a by-product. Glucose is used for energy (respiration) or converted to starch, cellulose, proteins, and fats.

Factors that affect photosynthesis rate: light intensity, CO₂ concentration, temperature, and water availability. These are limiting factors — when one is in short supply, it limits the overall rate even if others are abundant. Photosynthesis is the foundation of almost all food chains on Earth.