Shell-builders use calcium carbonate molecules (caco3) to build their shells. which of the choices above could be a source for the carbon atoms in the calcium carbonate (caco3) molecules? a) e. b) a. and e. c) b. thru e. d) b, c, and e

The question is incomplete, the correct question is;

Shell-builders use calcium carbonate molecules (CaCO3) to build their shells. Which of the following choices could be a source for the carbon atoms in the calcium carbonate (CaCO3) molecules?

respiration by organisms such as plants, animals and microbes

burning coal

calcium ions

car exhaust

wildfires

Answer is all of the above options except calcium ions.

The source for the carbon atoms in the calcium carbonate (CaCO3) molecules include respiration by organisms such as plants, animals and microbes , burning coal , car exhaust  and wildfires.

Explanation:

Shell-builders (coral, oysters, lobsters, sea urchins, phytoplankton) utilize calcium carbonate molecules (CaCO3) to build their shells. The respiration process by organisms such as plants, animals and microbes, burning of fossil fuels, vehicle exhaust, wild fire etc produces carbon dioxide (CO2) and release it into the atmosphere. Oceans absorb carbon dioxide in the air by diffusing and dissolving it into the surface water. The amount of CO2 that dissolved in the water depends on concentrations of CO2, temperature of the water, wind, etc.

Phytoplanktons (microscopic, one-celled organisms) also bring carbon into the ocean from the air through photosynthesis, where they convert the carbon dioxide and water into glucose and other carbon compounds. These carbon compounds are consumed by the marine organisms and some carbon eventually ends up in deep seafloor sediments. The other processes which involved in the transfer of carbon from the air into deep seafloor sediments include photosynthesis , decomposition , waste products, etc.

The CO2 dissolved in the ocean combines with water molecules to produce carbonate (CO3-) ions, which then combine with calcium ions in the seawater to form calcium carbonate (CaCO3). This calcium carbonate is used by shell building organisms to build their shells, plates, inner skeletons etc.

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