[ bī′ō-jē′ō-kĕm′ĭ-kəl ]
The flow of chemical elements and compounds between living organisms and the physical environment. Chemicals absorbed or ingested by organisms are passed through the food chain and returned to the soil, air, and water by such mechanisms as respiration, excretion, and decomposition. As an element moves through this cycle, it often forms compounds with other elements as a result of metabolic processes in living tissues and of natural reactions in the atmosphere, hydrosphere, or lithosphere. See more at carbon cycle nitrogen cycle.
Exercise Caution With These Telltale IdiomsThe following idioms are helpful reminders to assess your circumstances and decide when to make a change.
Why Did “Noon” Used To Mean 3:00? To most, the word noon signifies a specific time of day–namely, 12:00 midday, a.k.a. “lunchtime.” The counterweight to 12:00 midnight. But, surprisingly, the term noon wasn’t always shorthand for midday at 12:00; in fact, it used to refer to a different time of day altogether. First, some essential background. Clocks and watches are relatively new inventions. Though some timekeeping devices, like sundials and water clocks, …
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