RuBisCO is not a perfect enzyme. It can also catalyze a competing reaction called photorespiration, where it binds with oxygen instead of CO2. This process can be wasteful, as it consumes energy and reduces the efficiency of photosynthesis. However, plants have evolved various adaptations to mitigate this inefficiency, such as the C4 and CAM pathways, which optimize carbon fixation in environments with high temperatures and low CO2 levels.