 Okay, so photosynthesis, the process whereby plants use light to absorb CO2 and convert carbon dioxide into carbohydrates, is that the most important biochemical process on the planet? Well, everyone thinks their research is the most important thing ever, but in the case of photosynthesis it really is the most important thing on the planet. Take your mind back millions of years to what was happening in the primordial oceans of the earth, long before humans had evolved. We saw the evolution of photosynthetic bacteria. These cyanobacteria produce something that's been essential for all life on earth, including the evolution of human beings, and that's oxygen. In the process of photosynthesis, we not only produce carbohydrates, but the light energy from the sun is used to split water and produce oxygen. And that oxygen provides the air we breathe as well as the carbohydrates that are necessary for our survival. Now without that oxygen, we'd have no plant life on earth, we'd have no human life, no animal life, even things like iron ore wouldn't exist without oxygen on the planet. So plants are responsible not only for our survival to produce the food we eat, but also the air we breathe.