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17 Cards in this Set

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What is carbon?
Basic constiuent of all organic compounds and is involved in the fixation of energy by photosynthesis (CO2).
What is the source of all carbon in both living organisms and fossil deposits?
Carbon Dioxide in the atmosphere and the waters of the Earth.
What is meant by diurnal fluctuation of Carbon Dioxide?
CO2 is down during the day as the plants withdraw the CO2 for photosynthesis, CO2 is up at night when photosynthesis ceases and plants respire CO2 into the atmosphere.
What is Nitrogen?
An essential constituent of protein, which is a building block of all living tissue.
What are the two forms of nitrogen available to plants?
Ammonium and Nitrate.
What are the two ways nitrogen enters the ecosystem?
Atmospheric Deposition and Nitrogen Fixation.
How is nitrogen supplied via atmospheric deposition?
By wetfall (rain, snow, or even cloud and fog droplets).
How is nitrogen supplied via nitrogen fixation?
High energy fixation (cosmic radiation, meteorite trails, and lightning) and Biological fixation (symbiotic bacteria lving in mutualistic association with plants).
What is ammonification?
NH4 occurs in the soil as a product of microbial decomposition or organic matter, wherein NH3 is released as a waste product of microbial activity.
What is nitrification?
Brings nitrogen to us via lightning which converts nitrates to nitrites.
What are the main reservoirs of phosphorous?
Rock and natural phosphate deposits.
How is phosphorous released by rocks and minerals?
Weathering, leaching, erosion, and mining for use as agricultural fertilizers.
What nutrient has both sedimentary and gaseous phases?
Sulfur.
What are the sources of sulfur that enter the Earth's atmosphere?
Combustion of fossil fuels, volcanic eruptions, exchange at the surface of the oceans, and gases released by decomposition.
What is the sulfur cycle?
Enters initially as hydrogen sulfide, which interacts with oxygen to form sulfur dioxide. Soluble in water, it is carried back to the surface via rainwater as weak sulfuric acid. In a soluble form it is taken up by plants starting with photosynthesis, turned into sulfur-bearing amino acids and transferred to the consumers.
What is the major source of free oxygen that supports life?
The atmosphere.
What are the two significant sources of altmospheric oxygen?
The breakup of water vapor through a process driven by sunlight and photosynthesis.