Carbon Cycle

• The carbon cycle is the biogeochemical cycle by which carbon is exchanged between the biosphere and living organisms.

• Carbon is an essential component of proteins, fats and carbohydrates which make up all LIVING ORGANISMS.

Carbon Cycle

Important Vocabulary– Cellular Respiration– Photosynthesis– Decomposition– Combustion– Fossil Fuels

• Coal• Oil• Natural Gas

Carbon Cycle

• Carbon exists in the Earth's atmosphere primarily as the gas carbon dioxide (CO2).

• Carbon is taken from the atmosphere and returned to the Earth by the process of PHOTOSYNTHESIS.

• Carbon can be released back into the atmosphere in many different ways, including:– Cellular Respiration– Decomposition– Combustion

Photosynthesis• Remember Photosynthesis?

– Plants take carbon dioxide from the atmosphere, combine it with light energy and water to produce glucose and oxygen.

CO2 + H2O + light energy → C6H12O6 + O2

(carbon dioxide) + (water) + light energy → (glucose) + (oxygen)

Cellular Respiration

• Remember Cellular Respiration?

• Cellular Respiration, performed by BOTH plants and animals, involves the breaking down of glucose into carbon dioxide and water.

C6H12O6 + O2 → CO2 + H2O

(glucose) + (oxygen) → (carbon dioxide) + (water)

• The Carbon Dioxide is then released back into the atmosphere.

Decomposition

• Carbon is returned to the earth and released into the atmosphere through the decay of plants and animals.

• Decomposers, such as fungi and bacteria, break down the carbon compounds in dead animals and plants and convert the carbon into carbon dioxide in the presence of oxygen, or methane if oxygen is not present.

Combustion

• Combustion is the burning of fossil fuels such as coal, oil, and natural gas. Combustion releases carbon that has been stored in the Earth’s crust for millions of years into the atmosphere as carbon dioxide.

Interesting Scientific Fact:

• When some prehistoric plants and animals died, they became buried over time by layers of Earth. During that time, they were changed into fossil fuels such as coal, oil, and natural gas. The carbon contained in those once living organisms is burned as a fuel for cars. That same carbon is then released into the atmosphere.

Humans Affects on the Carbon Cycle

• Combustion (burning fossil fuels)– Driving their cars A LOT!

• Deforestation (destroying vegetation that absorbs carbon dioxide)

REMEMBER THIS!!!• Carbon enters the atmosphere through

cellular respiration, decomposition, and combustion.

• Carbon is absorbed from the atmosphere through photosynthesis.

• Humans have GREATLY impacted the carbon cycle by putting more carbon dioxide into the atmosphere through combustion than what is removed by photosynthesis!

Carbon Cycle Summary

• Now you have learned about the carbon cycle, check out the:

Carbon Cycle Animation

Questions???

Question 4: How does carbon enter the atmosphere?

Question 5: How is carbon removed from the atmosphere?

Question 6: How does carbon enter living organisms?

Question 7: How are humans impacting the carbon cycle and what is one of the results from human impact?