The process of photosynthesis require carbon dioxide and water in the presence of sunlight and the product formed is glucose and oxygen (byproduct).
This glucose is broken down in the presence of oxygen and energy released is stored in the form of adenosine triphosphate.
The carbon dioxide that is used by plants is released by animals and oxygen, carbohydrate is given by plants to animals for the process of cellular respiration.
In the above two processes water is only required in photosynthesis not in cellular respiration.
When carbon dioxide concentrations drop, Earth cools, some water vapor falls out of the atmosphere, and the greenhouse warming caused by water vapor drops.
Transpiration produces a tension or pull on the water in the xylem vessels by the leaves. Water molecules are cohesive so water is pulled through the plant .
