Hope you have enjoyed our biology tips so far. More to come if you want them ...
Today's topic should be familiar to you. Is energy the same as nutrient cycling?
No, they are not. Actually they're really quite different. Even though your food contains energy and nutrients, they are not the same. Although energy and nutrients are both absolutely necessary for life, their behavior could hardly be more different.
All living systems, from cells to bodies to ecosystems require energy to function. No energy, no life. Since the sun is the ultimate source of energy for all the critters on our tiny planet, we are dependent on outer space for our existence. Not only are the origins of the energy stored in your body or flowing through your body to be found in outer space, this energy will eventually return to the vast darkness of our infinite universe. Oooh! That sounds existential.
The energy of the sun is primarily captured during photosynthesis and ultimately converted into chemical energy, the energy contained in the bonds of compounds. When those compounds, in turn, are broken down so the chemical energy can be used for various cellular and organismal functions, a lot of it is lost as heat and it flows back into space.
Eventually all the energy that arrives from the sun is returned to outer space in a different form, usually heat but sometimes as light (think about the luminescence you sometimes see in the ocean. It's mostly caused by ocean-dwelling, light-producing bacteria). So the overall pattern of energy is: sun  organisms  outer space.
Nutrients are also essential to life and their ultimate origins, if we go back far enough in time, are also in outer space. Like the song says, we are stardust. Despite the romance of this statement, nutrients are a bit more mundane in their behavior than energy.
Nutrients are compounds or elements that organisms require to survive, like H2O or carbon or nitrogen or phosphorus. Cells rapidly perish in the absence of the appropriate nutrients. Having the right kinds and amounts of nutrients keeps your cells and their myriad chemical reactions happy.
Rather than behaving exotically like energy, cycling through biological systems and back into space, nutrients are cycled from the biotic to the abiotic over and over. By the way, living organisms are the "biotic" and their physical environments are the "abiotic".
In part this means, oddly enough, you are what you eat. You remember those french fries you had for lunch yesterday? They were originally real potatoes that grew in the ground. Those potatoes got their nutrients from the air and the soil and the water. The grease the fries were cooked in was derived from animal fat. Guess what? Those soil nutrients and animal fat molecules were turned into "french fries". You ate them and some of them became you!
Yes, it's true. Atoms that were once in the ground and the air went into the potato and eventually into your cells and tissues. We don't even want to think about the animal fat molecules that became part of the french fries and then became part of you. Yuck!
Your atoms and molecules turn over from time to time. And they return to the abiotic when you poop, pee, fart, perspire, spit, exhale, sneeze, wheeze or...gasp, die and decompose. Sorry, that's life. Much of you will eventually be decomposed by various microorganisms which will incorporate your atoms and molecules into their cells. Your remaining atoms and molecules will be in the air or water or soil for a while, the abiotic part, but eventually they will be recycled into the biotic part, once again.
Let's take this to its logical conclusion. Since nutrients cycle over and over through the biotic and abiotic, it is conceivable that your body currently contains an atom that once found its way into a long extinct dinosaur (when it was still alive!). Very cool! On the other hand, maybe you have an atom in your body that used to be in an ancient slime mold.
Until then, stay tuned for more biology tips.
Seize the Day!
Dr. Wayne Huang
"The Rapid Learning Coach"
BioTips@RapidLearningCener.com
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