The answer is nuclear fusion, since this is such a dominant source of energy as opposed to nuclear fission which takes place as well but at much smaller rates.
No air does not have cells it’s not living
The tadpole contains gills but doesn't have legs nor lungs.
however the adult frog contains the opposite. It has both lungs and legs but doesn't have gills. This is due to tadpole leaves in the water and the frog leaves on both land and sometimes in the water.
