8.4 Challenges to Photosynthetic Efficiency

The efficient functioning of photosynthesis faces two major challenges. The first is that if more light energy is absorbed than the Calvin cycle can use, excess energy can damage the cell. The second challenge stems from a property of rubisco: This enzyme can catalyze the addition of either carbon dioxide or oxygen to RuBP. The addition of oxygen instead of carbon dioxide can substantially reduce the amount of carbohydrate produced.