When people breath or when trees are cut down
Respiration by animals is one of the ways through which carbon dioxide is released to the atmosphere. The other way is through burning fuels that are carbon-based.
Rotting timber adds either methane or carbon dioxide to the atmosphere.The missing trees no longer remove carbon from the air through photosynthesis.
Oxygen is extracted, by the lungs, from the air taken in, and carbon dioxide is released from them. So, there are really two products - oxygen and carbon dioxide.
Carbon dioxide is the waste product of the process of respiration in plants and animals and it is also released into the atmosphere by active volcanoes.The burning of coal and wood
Oxygen and carbon dioxide are exchanged across the lining of a frog's mouth. Oxygen is absorbed from the air into the blood vessels, while carbon dioxide is released into the air from the blood vessels.
Got this from wikianswers..hope it helps:) Coffee and air are mixed, but the coffee is heterogeneous, and the air is uniform and both have many substances in their chemical composition, the two have water, carbon, nitrogen, oxygen, and hydrogen, but in different molecular ways.
oxygen and carbon
What are two places where lots of carbon is stored
superposition and carbon dating
carbon dioxide
this site isn't useful
by the nose and mouth