2.3.1—Biogeochemical cycles purpose

Biogeochemical cycles move finite elements between organisms and abiotic stores; uptake makes an element available for life and decomposition returns it.

Follow the element, not just the organism: identify its store, the process moving it, and whether a human action speeds or blocks that flow.

Nitrogen in soil nitrate enters a plant, moves to a herbivore, returns in waste, then microbes convert it back to an inorganic form.

Label the element’s current store and the process on the arrow; this prevents confusing a transfer with a transformation.

Cycles reuse matter, but they do not mean every atom returns quickly or through the same route.