sentences: plants are a source of oxygen through photosynthesis
docs: photosynthesis is process. photosynthesis_in_plants is oxygenic_photosynthesis. photosynthesis_in_plants is general_photosynthesis. photosynthesis is photo_chemical_process. photosynthesis_in_plants is physiological_process. oxygenic_photosynthesis is general_photosynthesis. photosynthesis is chemical_process. general_photosynthesis is production. photosynthesis is process_by_which_leaf_makes_food. photosynthesis_in_cam_plants is photosynthesis_in_plants.