Short answers, pulled from the story.
Jan Ingenhousz discovered that plants release oxygen in the year 1779. He performed an experiment where he placed a plant under water and exposed it to sunlight, observing that it released bubbles of gas which he identified as oxygen.
The Great Oxidation Event occurred roughly 2.4 billion years ago when cyanobacteria evolved the ability to split water and release oxygen as a waste product. This event triggered a crisis for many existing life forms that could not survive in an oxygen-rich environment and eventually allowed for the evolution of complex multicellular life.
Melvin Calvin and his colleagues at the University of California, Berkeley, elucidated the Calvin cycle in the 1950s. They used radioactive carbon-14 to trace the path of carbon atoms and identified the enzyme RuBisCO as the key player in capturing carbon dioxide.
Quantum coherence allows energy to explore multiple pathways simultaneously when a photon strikes a chlorophyll molecule, ensuring near-perfect efficiency in capturing light energy. This process enables plants to harvest light energy with an efficiency that far surpasses human-made solar panels which typically convert only 6 to 20 percent of sunlight into electricity.
The endosymbiotic theory posits that a primitive eukaryotic cell engulfed a photosynthetic cyanobacterium billions of years ago and formed a symbiotic relationship with it. Over time the cyanobacterium lost its independence and transferred many genes to the host nucleus while retaining its own circular DNA and the ability to perform photosynthesis.
Photosynthesis captures approximately 130 terawatts of energy from the sun every year, which is eight times the total power consumption of human civilization. This process converts between 100 and 115 billion tons of carbon into biomass annually and forms the foundation of almost all food chains on Earth.