It was the carbon in carbon dioxide, not the oxygen, that was the ready fuel for emergent life. The magic trick was transforming the carbon in CO2 into energy.
Photosynthesis powers life on our planet. ~ American physicist Franklin Fuller
The chemical equation for photosynthesis is: 6 CO2 +
12 H2O + sunlight energy → C6H12O6 + 6 H2O + 6 O2.
A photosynthesizing organism derives energy from sunlight via charge separation; forging atmospheric carbon dioxide and water into energy-storing sugars by freeing electrons to work chemical transformations via photonic energy. Charge separation is the process of an atomic electron being excited to a higher energy level by absorbing a photon, and thereby leaving its home to join a nearby electron acceptor molecule.
Chloroplasts – plant organelles that conduct photosynthesis – have chlorophyll that absorb various wavelengths of light, with peak inputs around 430 nanometers (blue light) and 660 nm (red). Chlorophyll is green because it shies from absorbing mid-spectrum green light (526–606 nm), which is thereby reflected.
O2 is a byproduct of photosynthesis; an oddity considering that oxygen is itself energy-rich by its easy reactivity. But throwing off water’s O2 makes sense in light of the photosynthesis system.
In plant photosynthesis, oxygen stubbornly sticks to the carbon in CO2, which becomes the backbone molecule upon which the target sugar (glucose: C6H12O6) is built. In the same reaction as evaporation, water molecules are split to liberate oxygen (O2) into the atmosphere.
The rate of charge separation for evaporation in photosynthesis is enhanced by coherent dynamics that are vibronic in nature. This allows photosynthesis to be optimal at the quantum level.
Hydrogen is the watery element elicited in photosynthesis; valued for its donation in the electron transport chain: the molecular processing system for deriving energy.
Carbon has a dual role in photosynthesis. It is the proton acceptor (HCO3–) in the very beginning of the photosynthetic reaction, and the terminal electron acceptor (CO2) at the end. This varied employment of different species in a reaction series illustrates the wondrous flexibility of carbon.