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

question 15

Multiple Choice

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 on 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

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Definitions:

Present Value

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Interest

The cost of borrowing money, typically expressed as a percentage rate over the period of the loan, or the return earned on investments.

Annual Interest

The amount of interest paid or earned over one year, often expressed as a percentage of the principal.

Blown Fuse Indicators

Devices that provide a visual or electronic signal indicating that a fuse has interrupted the circuit it protects due to an overcurrent condition.