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The Carbon CycleAnswerKey.docx


									The Carbon Cycle – Science 1206                           Name: _______________________

    1) What is the key element for living things?

   2) Where can inorganic carbon be found?

           in the atmosphere and dissolved in the oceans as CO2

   3) Write out the reactants and products for the photosynthesis equation.(Names and formulas)

               6CO2    + 6H2O       + light                          C6H12O6 + 6O2

           Carbon dioxide + water + light energy                   sugar(glucose) + oxygen

  4) Write out the reactants and products for cellular respiration. (Names and formulas)

                      C6H12O6 + 6O2                        6H2O    + 6CO2

                       Glucose + oxygen                    water + carbon dioxide

  5) Why is the carbon cycle called “The Carbon Cycle”?

     Photosynthesis and cellular respiration are complimentary processes and carbon is used over and over in

 6) How does carbon from living things return to the atmosphere or water?

    returned as carbon dioxide from body wastes and decay

7) Sometimes carbon is converted into rock or fossil fuels. Give three examples.
     1) coal
     2) oil
     3) natural gas
8) How would the carbon in the above items be released?
    a) uplifting
    c)burning fossil fuels

Reservoirs for Inorganic Carbon-Delays in the Cycle

9) What are the three main reservoirs for inorganic carbon?

  a) atmosphere b) the oceans c) Earth’s crust

9) Where is a lot of inorganic carbon held?

   held as dissolved carbon dioxide in the oceans

10) Some carbon dioxide reacts with seawater to form the carbonate ion and the bicarbonate ion. What are the
   formulas for these ions?

       CO3 - carbonate       HCO3 - bicarbonate

11) The ions mentioned above combine with calcium to form what compound?

   calcium carbonate (CaCO3)

12) Where is this compound used?

   shells and bones of living things

13) Where does much of the carbon in carbonates end up?

  much of it ends up as sediment on the ocean floor
14) Explain why sedimentary rocks form the largest reservoir of carbon.

  The rock limestone is made up of the remains of shells and living things.

Reservoirs for Organic Carbon

15) Organic carbon is in the bodies of living things. All creatures die and decompose, returning carbon to the cycle in an
    inorganic form. Describe the exception to this rule?

    Ecosystems like bogs, store huge quantities of carbon in organic form. In a bog decomposition is slow.
    carbon atoms remain locked in dead plant matter. With time this can be become coal.

16) How does oil form?

   decayed aquatic animals get trapped in mud or sediment in a low oxygen environment.

Human Impact on Carbon cycle

17) How have humans modified the carbon cycle?

     Through mining, burning fossil fuels, burning forests, clearing vegetation

18) How does the destruction of vegetation affect the carbon cycle?

    this reduces the amount of photosynthesis

19) Where does most carbon dioxide released into the air eventually go?

   Eventually becomes dissolved in seawater.

20) How long can the organic carbon trapped in coal be stored?

           Millions of years

Inorganic carbon held as dissolved CO2 (carbon dioxide) in the oceans.

When not in organic form, carbon is found in the atmosphere, the oceans, and Earth’s crust.

Largest reservoir of carbon is located in Earth’s crust in sedimentary rocks.

Bogs can store organic carbon, and eventually form coal.

Organic carbon on the ocean floor can form oil.

Draw a diagram of the Carbon Cycle:

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