How do plant's alter the earth's atmosphere by removing carbon?

First of all, we must understand the effect of excess carbon in the atmosphere.  Excess carbon includes mostly carbon dioxide as well as water vapor and methane.

Excess carbon in the atmosphere  increases the temperature of the earth by absorbing infrared and near infrared light. (ref:  http://www.ideaconnection.com/solutions/7510-Excess-Carbon-Dioxide-in-Atmosphere.html)

Carbon dioxide is a greenhouse gas.

Greenhouse effect  refers to circumstances where the short wavelengths of visible light from the sun pass through a transparent medium and are absorbed, but the longer wavelengths of the infrared re-radiation from the heated objects are unable to pass through that medium. The trapping of the long wavelength radiation leads to more heating and a higher resultant temperature. Besides the heating of an automobile by sunlight through the windshield and the namesake example of heating the greenhouse by sunlight passing through sealed, transparent windows, the greenhouse effect has been widely used to describe the trapping of excess heat by the rising concentration of carbon dioxide in the atmosphere.

The increasing amount of carbon dioxide in the atmosphere is increasing the temperature of the earth by absorbing infrared and near infrared light.

 

How do plants help remove excess carbon?  Photosynthesis

 

Plants use the energy from the sun to remove carbon dioxide from the atmosphere and use it to make carbohydrates (sugars).

 

Plants take up CO2 (carbon dioxide) from the atmosphere and uses it for the metabolic production of sugars.  Carbon dioxide is fixed or incorporated into specific organic molecules by the Calvin Cycle which is the second stage of photosynthesis.

 

 

 

Understanding the Krebs Cycle

What is the Krebs Cycle?

The Krebs Cycle is the third stage of cellular respiration.  It is a cyclic metabolic pathway in which cells use pyruvate from glycolysis to produce 3NADH and 1FADH2,  2CO2, and 1 ATP per turn.

NADH and FADH2 are electron carriers.  These two molecules are shuttled to the inner mitochondrial membrane to be used by the Electron Transport Chain (more on that later).

The Krebs Cycle occurs in the mitochondrial matrix.

Pyruvate from glycolysis enters the mitochondrion via the pyruvate dehydrogenase complex (PDHC) which is a multienzyme complex located in the outer mitochonrial membrane. 

The PDHC compelx converts pyruvate to acetyl-CoA.

Two pyruvates are formed at the end of glycolysis.  Therefore,

2Pyruvate  ----->  2acetly-CoA   +  2 CO2

Remember, the overall equation for cellular respiration is:

C6H12O6   + 6O2  -------->  6CO2   +   6H20   +  energy (ATP)
glucose     +  oxygen  -----> carbon dioxide  +  water  +  energy

Glycolysis converts the glucose to pyruvate.

Pyruvate is converted to acetyl-CoA yielding two carbon dioxide molecules.  The other 4 CO2 are produced during the Krebs Cycle.