AP BIOLOGY

Detailed explanation-1: -Reservoir: Reservoirs are places where essential elements are sequestered for long periods of time. biogeochemical cycle: A pathway by which a chemical element or molecule moves through both biotic (biosphere) and abiotic (lithosphere, atmosphere, and hydropshere) compartments of the planet.

Detailed explanation-2: -So the correct answer is ‘Nitrogen cycle’.

Detailed explanation-3: -biogeochemical cycle In biogeochemical cycle. …be considered as having a reservoir (nutrient) pool-a larger, slow-moving, usually abiotic portion-and an exchange (cycling) pool-a smaller but more-active portion concerned with the rapid exchange between the biotic and abiotic aspects of an ecosystem.

Detailed explanation-4: -Nutrient cycling involves sources of nutrients called reservoirs, which are either biotic (living) or abiotic (nonliving). For example, the atmosphere is an abiotic reservoir for carbon (in the form of carbon dioxide). Biomass is a biotic reservoir for carbon (in the form of organic molecules).