What is the difference between the first and second stages of photosynthesis?

What is the difference between the first and second stages of photosynthesis? What role does water play in air supply? How does carbon dioxide get into the leaf? Why is the leaf called the organ of air nutrition in green plants?

During the first stage, atmospheric oxygen, hydrogen ions, energy are formed, and photolysis of water occurs. In the dark phase, organic matter is formed, carbon dioxide is reduced, and ATP is absorbed. During the air supply, water evaporates. The leaf has a large area, contains the main tissue, chloroplasts, and therefore is an excellent organ for photosynthesis. Its upper part is covered with a thin skin through which light, which is needed for plastic exchange, easily penetrates.