Some plankton make shells of calcite/aragonite,that is,CaCO₃.They do this metabolically by combining calcium (Ca²⁺)ions and bicarbonate (HCO₃-)ions that are both dissolved in water around them.When such plankton dies,their shells sink downward to become sediment of the ocean floor.Under some conditions in the ocean or sediment,the CaCO₃ shells may dissolve,locally enriching the pore waters or deep-ocean waters in HCO₃-.Portions of this total process could be considered belonging to each of the following cycles,EXCEPT for the ____________.
A)carbon cycle
B)biogeochemical cycle
C)methane cycle
D)calcium cycle

Question

Quizplus · Accepted Answer

The process described in the passage does not involve the methane cycle. The other three cycles - carbon cycle, biogeochemical cycle, and calcium cycle - are all involved in some way in the processes described.

Some Plankton Make Shells of Calcite/aragonite,that Is,CaCO₃