1. THE CARBON CYCLE
CHAPTER 2.5
Carbon Cycle

2. THE CARBON CYCLE Carbon is an element.
Carbon atoms are the basis for all living things (called organic matter) and for all matter that was once living (called detritus).
Carbon is stored in FOUR places:
Living things
The atmosphere
The ocean
The earth’s crust

3. These storage places are called carbon sinks.
Carbon is removed from the atmosphere by plants when they photosynthesize to make sugar.
Reactants Products
6CO2 + 6H2O + light = C6H12O6 +6O2
carbon dioxide + water + light = sugar (glucose) + oxygen

4. Carbon is returned to the atmosphere by plants and by animals when they respire or exhale.
Reactants Products
C6H12O6 + O2 = CO2 + H2O
sugar + oxygen = carbon dioxide + water

5. Photosynthesis and cellular respiration are complementary processes, and because the carbon that they use is repeatedly cycled through both processes, this relationship is often called the CARBON CYCLE.

6. Most of the carbon that forms living organisms is released to the atmosphere or water as carbon dioxide as dead organisms decay.
Under certain conditions, the decay process is delayed, and the organic matter may be converted into rock or fossil fuels such as coal, petroleum and natural gas.

7. This carbon is not released until the combustion process takes place through burning the fuels.

8. Reservoirs for Inorganic Carbon
Carbon, when not in organic form, can be found in three main reservoirs (storage areas):
The atmosphere
The oceans
The Earth’s crust

9. The Ocean
Carbon is also found in seashells (both large and microscopic). When these fall to the bottom of the oceans and get covered with sediment over millions of years they will form limestone.

10. (Millions of tonnes of soil)
Shells and Bones
Sink to the bottom of the ocean
Covered by sediment (Millions of years)
Form limestone

11. Reservoirs for Organic Carbon
Organic carbon is also held in reservoirs – the bodies of living things.
All living things die and decomposition eventually returns the carbon to the cycle in inorganic form.

12. Q/A What is the human impact on the Carbon Cycle?
Humans are increasing CO2 in the atmosphere by clearing away vegetation (forests) and by burning fossil fuels.

13. One Important Exception
Bogs – store huge quantities of carbon in organic form
Bogs have very little oxygen, therefore decomposition is very slow
Carbon atoms may remain locked away in dead plant matter (peat) for many years in a bog.
When plants decompose in a bog, they form peat that can get trapped under sediments over millions of years and form coal (another form of fossil fuel).

14. Die and decompose in a bog to form peat
PLANTS
Die and decompose in a bog to form peat
Millions of years and tonnes of pressure form coal

15. Classwork
Use your text, read pg and answer the following questions:
1- 7
Work quietly at your desk.
You may listen to your ipod/ mp3 while working.
If I hear the music, you lose this privilege.
When you are done these questions- Start reading about the Nitrogen Cycle on Pages

16. Review for Test Things to know:
The written and chemical forms of photosynthesis and cellular respiration.
In photosynthesis, where in the cell is the change taking place?
In cellular respiration, where in the cell is the change taking place?
The completed table on pg. 84
Where our Carbon Sinks are.
Where our Carbon Reservoirs are for inorganic and organic Carbon.

17. Response to Planet Earth:
On the quiz you will be expected to respond to the movie we watched, “Planet Earth:Caves”.
Things to think about:
Types of Ecosystems we saw
Different animals we were shown.
Food webs that we were shown
Some of these ecosystems did not have a plant life/ direct sunlight basis.
Any other remarks or comments

18. CLASSWORK CARBON CYCLE HANDOUT
You can listen to your ipod/ mp3 players while completing the handout.
MAKE SURE THEY ARE ON LOW!