In countries at far northern latitudes, the winter months tend to be so cloudy that astronomical observations are nearly impossible. why can’t good observations of the stars be made at those places during the summer months?

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.

So are u adding some additional catalyst