Suppose you are on a concrete surface and suddenly slip as you step on a patch
of ice. How do the pairs of action and
reaction forces differ when you are on
the dry walk and when you step on the
ice?

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.

Shy diving is the only sport which doesnot require a high level of physical fitness