the free energy released by the blank reactions of blank is stored in blank. the energy released by its hydrolysis to blank and pi drives the blank reactions of blank, which synthesize the complex molecules. also, during hydrolysis in mechanical and transport work, blank is transformed into blank. in these transfers and transformations, some energy is lost as heat. all the reactions of a cell require enzymes, which ensure efficient cell function by binding substrates and blank activation energy, thus speeding up metabolic reactions.