Why is it difficult to use the law of conservation of energy to calculate the effects of a collision? A. Energy is not conserved B. Energy is only conserved during inelastic collisions.
C. Energy is destroyed during a collision.
D. Energy is converted to heat during a collision.

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.

Iwould think it would be efficiency.