How does photosynthesis affect the flow of energy in the biosphere?

Photosynthesis occurs only when plants can obtain carbon dioxide, water and light from their external environment, products produced are sugars and oxygen. All living things depend on the process of photosynthesis, which it provides the continuous input of energy necessary to sustain ecosystems. Photosynthesis enables green plants to obtain energy directly; plants and animals obtain this energy indirectly from the food they eat.