What is Photosynthesis?

Literally, the word Photosynthesis means "building from light." The sun is the single most abundant source of energy at the surface of the earth, and living things long ago figured out how to harness that energy. What green plants and other organisms do it pretty remarkable, but it's pretty easy to summarize. They take a very low-energy compound like water, and then use the energy of sunlight to kick the low-energy electrons in water up to a much higher energy level. This is very similar to the way in which solar panels produce electricity from sunlight - except that plants don't make electrical current. Instead, they use those high energy electrons to build energy-rich sugar molecules from carbon dioxide. These sugars can then be stored to provide energy for just about any activity the cell needs. A cool system, and a pretty important one, too!

Why Photosynthesis Matters

It's the key to life on earth. No kidding. Whether it's meat, fruit, vegetable, or something else, everything we eat can be traced to photosynthesis. For that matter, energy resources like coal, oil, and natural gas are the result of photosynthesis, too. Over millions of years, the decayed bodies of plants and animals, all dependent upon photosynthesis, have given rise to deposits of fossil fuels throughout the earth. And, finally, photosynthetic organisms dominate the earth. They shape the composition of the atmosphere (that's where the oxygen we breathe comes from), form whole ecosystems, and produce both the energy and the mass upon which food chains depends. In short, life on this planet is unthinkable without photosynthesis.