If the reaction between a glucose molecule and oxygen releases energy, what must occur during the reaction in which glucose is produced?In other...

You are also talking about the basic, life-enabling cycle of respiration---->photosynthesis---->respiration

water + carbon dioxide + energy --> glucose + oxygen

Life requires energy; thing tend toward entropy (randomness) in the universe. Life is a case of going against entropy, and requires energy to do so. The energy to do this is basically stored by plants, during the process of photosynthesis, in the complexity of the structure of glucose. When glucose is broken down during respiration, energy is released.