What does a pshycometer measure

It measures the relative humidity in the atmosphere through the use of two thermometers. The first, a dry bulb thermometer, is used to measure the temperature by being exposed to the air. The second, a wet bulb thermometer,measures temperature by having the bulb dipped in a liquid.

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.