PGA ( Phosphoglyceric acid) is a first stable product of photosynthesis which under goes reduction. Six molecules of 3-PGA is reduced to six molecules of a chemical compound called glyceraldehyde 3-phosphate (G3P). In this conversion; six molecules of both ATP and NADPH are used. In this reduction reaction, there is gain of electrons by 3-PGA. NADPH is oxidized to NADP+ to give elections and energy is given by ATP.
There has to be one side with a high concentration and another side with a lower concentration
Ecosystems disturbed by a nature will be eventually restored unless it's a really big cataclysm, but most of the ecosystems are now a human caused disturbance. For example there are plenty of species which are already extinct or nearly extinct because of hunting industry.