Question

Which of the carbon atoms do organisms use to make their shells? (CO32-)?


carbonate (CO32-)


carbonic acid (H2CO3)


bicarbonate (HCO3-)

Answer 1

Organisms use carbonate ions (CO₃²⁻) to make their shells. Many marine organisms, such as corals, mollusks, and some types of plankton, utilize carbonate ions from seawater to form calcium carbonate (CaCO₃), which is the primary component of their shells and skeletons. The carbonate ions can be derived from bicarbonate (HCO₃⁻) or carbonic acid (H₂CO₃), but it is the carbonate ions themselves that are incorporated into the shells.