Energy
A photon from the sun reaches Earth, strikes a plant, causes the electron in the outer shell of some atom to jump to a higher state. The photon vanishes, its energy absorbed. That energy will find its way into an electron attached to an atom of oxygen and, in a series of steps, simple carbon dioxide molicules will be torn apart and sewn together into molicules of sugar, containing that solar energy, with the oxygen discarded into the atmosphere.
Sugar isn't the only place the energy gets stored, of course, nor is oxygen the only actor. Phosphorus is a major actor, in an enzyme called ATP (when there are three 'P') or ADP (when there are two 'P'), the extra 'P' having a big part in unlocking the stored energy, breaking the glucose (sugar) apart and tacking a spare electron onto an oxygen atom somewhere.
A lot of the energy conversion work in our bodies is done in primative structures similar to bacteria called mitochondria (not mitochlorians, which are the fictional source of the force, not energy).
The energy conversion process is going on constantly because we always use energy one electron at a time. Most of what we do requires many electrons, usually millions, so our bodies are constantly cranking them out.
The process isn't perfect. Between the photon striking a plant and our thinking a thought or taking an action there is a lot of waste. Just recovering energy from glucose is only about 60% efficient (or was that 40%?).
What gets wasted? Well, there are some waste products, some chemicals that get thrown away along the way as useless. But the biggie is heat. An electron in an atom will drop to a lower level, a photon will be emitted, and that energy will dissipate into the surroundings. Or something, somewhere, will shake a little harder because of a chemical reaction that took place along the way.
But we live on sunlight.
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Comments (3)
We are starlight living on starlight. Cool.
It's interesting that I read this after having seen The Matrix for the second time this week. Tonight I will be watching The Matrix: Reloaded. Have you seen either?
Yes, I've seen The Matrix repeatedly -- we have the video tape. I've seen previews of the sequel and have felt no compelling urge to pay theater prices.