Answer :
Final answer:
Plants need to maintain a high CO₂ concentration in leaves to prevent photorespiration, hence the correct answer is d) It helps prevent photorespiration.
Explanation:
It is critical for plants to maintain a high concentration of carbon dioxide (CO₂) in their leaves primarily to prevent photorespiration, a process that competes with photosynthesis and decreases a plant's efficiency in producing energy. When the CO₂ concentration is high, the enzyme RuBisCO can effectively catalyze the conversion of CO₂ and RuBP into G3P, which is necessary for the regeneration of RuBP.
This process is part of the Calvin-Benson cycle, essential for photosynthesis, where RuBP is synthesized from G3P. A high CO₂ environment ensures that Rubisco binds to CO₂ instead of oxygen, preventing photorespiration, which can consume resources and energy without yielding sugars the plant can use.
Photorespiration occurs when the CO₂ levels inside the leaf drop and oxygen levels rise, causing RuBisCO to catalyze the reaction with oxygen instead of CO₂. This not only leads to a wasteful process using ATP and reducing the production of G3P but also inhibits the regeneration of RuBP, thereby slowing down the Calvin cycle. Maintaining high CO₂ concentrations minimizes photorespiration, ensuring efficient photosynthesis and optimal growth conditions for the plant.
C4 and CAM photosynthesis are adaptations some plants have developed to minimize photorespiration by fixing CO₂ into four-carbon compounds in cells where the CO₂ concentration remains high, even when the stomata are closed to reduce water loss.