sentences: cellular respiration is a source of energy for cell activities
docs: anaerobic_cellular_respiration is cellular_respiration. anaerobic_cellular_respiration is anaerobic_biochemical_process. cellular_respiration is catabolic_pathway. air_respiration is respiration. cellular_respiration is chemical_synthesis. bacterial_respiration is cellular_respiration. respiration is metabolism. air_respiration is physiological_function. cellular_respiration is cellular_respiration.