biogeochemical cycle

[ bī′ō-jē′ō-kĕmĭ-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.

QUIZZES

THINK YOU’VE GOT A HANDLE ON THIS US STATE NICKNAME QUIZ?

Did you ever collect all those state quarters? Put them to good use on this quiz about curious state monikers and the facts around them.
Question 1 of 8
Mississippi’s nickname comes from the magnificent trees that grow there. What is it?
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.