Without photosynthesis, life would not have been able to proliferate the way it had over the past several million years. Identify which single called organism made this possible

This is the Photosynthetic Cyanobacteria. it was the ability of this unicellular organisms million of years ago, through photosynthesis; that  lead to the emergence of  separate singular organisms  the  plants. Plants constantly undergo photosynthesis as it absorbs CO2, and make use of sunlight to to produce carbohydrates  for  animals to survive. And this leads to  the emergence of animals which feeds on the plants, and therefore re population of the  Earth occurs.

Explanation: