a leaf performs photosynthesis / gas exchange
photosynthesis is not chemical_process. photosynthesis is process. photosynthesis is not process. photosynthesis is chemical_process. photosynthesis is process_by_which_leaf_makes_food. photosynthesis is photo_chemical_process. leaf is plant_organ. photosynthesis is not process_by_which_leaf_makes_food. photosynthesis is not photo_chemical_process.