During a thunderstorm, then underside of a cloud becomes positively charged, which induces a negative charge on the ground underneath it (just like two parallel plates). If the potential difference between the cloud and the ground is 1.20 gigavolts (1 GV = 1 x 109V) and the electric field intensity between them is1.92 x 106 N/C, downward, how far above the ground is the bottom of the cloud?

The answer is water molecules are split.cellular respiration and photosynthesis are complement  reactions to each other. these are reverse reactions. in cellular respiration glucose and oxygen yield water and carbon dioxide. so, when respiration begins,  glucose molecules are split. in the opposite reaction - in photosynthesis, carbon dioxide and water yield glucose and oxygen. thus,  when respiration begins, water molecules are split.