What is the biospheric role of photosynthesis?

Photosynthesis plays not only the most important role for all green plants, but also for the biosphere as a whole. Through this process, the plant receives energy. Animals, which are all heterotrophs, receive, when eating plants, those substances that they themselves cannot produce, since they do not have chloroplasts in their cells. Another important function of photosynthesis is the regulation of air composition. For several hundred thousand years, the composition of the air has remained practically unchanged. It is 78% nitrogen, 21% oxygen and 0.03% carbon dioxide. All this is due to photosynthesis.