Energy conversion of light (autothrophs - photosynthesis)

The four electrons that are one of the products of the splitting of two water molecules are lifted to a higher energy level by the four fotons. Some of this energy is used to pump protons into the tylakoid inner space. The energy stores in this proton pool has a similar funcrion as water reservoir is used to produce another high energy molecule - ATP like water gradient is used in turbines to produce power.

come from water are lifted to a higher energy level by the fotons (in the photosystem II named so because of historical reasons). Some of this energy is used to establish a proton gradient which is used to produce another high energy molecule - ATP like water gradient is used in turbines to produce power.

The electron is once again lifted by light to a higher energy level in the photosystem I. Some of its energy and the electron itself are used to create another high energy molecule - NADPH which helps with its energy to produce carbohydrates in the carbon fixation cycle. The carbon comes from the carbon dioxide, which is a "waste" product of heterothrophs.