Biology

High oxygen concentrations are likely to cause an increase in photorespiration, which in turn decreases the efficiency of the Calvin cycle.

In the Calvin cycle, carbon dioxide is typically fixed into glucose. However, when the plant is exposed to a high concentration of oxygen, a process known as photorespiration can occur.

Photorespiration happens when the enzyme RuBisCO, which is responsible for fixing CO₂ in the Calvin cycle, mistakenly fixes oxygen (O₂) instead of c...