Earth Science/Biology Standard 7a. Students know the carbon cycle of photosynthesis and respiration...
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Transcript of Earth Science/Biology Standard 7a. Students know the carbon cycle of photosynthesis and respiration...
Earth Science/Biology Standard
7a. Students know the carbon cycle of photosynthesis and respiration and the nitrogen cycle.
What is nitrogen? Chemical element N, atomic number=7
Colorless, odorless, tasteless, inert gas
Makes up 78% of the atmosphere
N2,Dinitrogen gas, (Diatomic )
Why is it important?
Proteins and nucleic acids (DNA, RNA) in living organisms
Nitrogen gas (N2)-> cannot be used directly.
* Animals get nitrogen from plants or animals that ate plants
Forms of nitrogen
Atmospheric Nitrogen: N2
Nitrate :NO3
Nitrite: NO2
Ammonia: NH4
What is the nitrogen cycle?•The process by which nitrogen is converted between its chemical forms
•It can be carried out by both biological and non-biological processes
•Bacteria are key element of the cycle
Where does it go?
• MicrobesMicrobes
Nitrogen fixationbreak apart N2
Atmospheric: lightning
Biological: bacteria
Industrial: great pressure and temperature
Atmospheric Nitrogen and Nitrogen Fixation
Triple bond is very stable Nitrogen gas- ammoniaMainly through bacteria
Bacteria•Single celled
•Very small, microscopic
Nitrogen fixing bacteria
Bacteria living in root nodules of LEGUMES (soybeans, peanuts, alfalfa)
Bacteria living in soil and water
Assimilation
Plants Nitrate->nitrite-> ammonium-> amino
acids, nucleic acids Ammonium-> amino acids, nucleic acids
(in legumes)
Animals eat plants
amino acids, nucleotides
Mineralization (ammonification) Plant or animal dies, animal excretes
waste
Bacteria convert organic nitrogen to ammonium
Nitrification
Bacteria convert ammonium to nitrate nitrite-> nitrate->ammonium Nitrate-> ammonium
Can seep into groundwater Health problems Environmental problems
Denitrification
Bacteria convert Nitrate to Nitrogen gas
Completes the cycle by returning nitrogen to the atmosphere
Increased Nitrogen emissions Cultivation of legumes
Artificial fixation of nitrogen
Nitrogen oxide from cars and factories
(greenhouse gas, destroys ozone layer)
In water…
Acidification
Eutrophication
Too much nitrogen in the water (mostly due to runoff from land) -> more algae (algal blooms) -> take up oxygen-> affects other organisms (animal lives die)
Earth Science/Biology Standards
7c. Students know the movement of matter among reservoirs is driven by Earth's internal and external sources of energy
What powers the water cycle?
What drives photosynthesis?(Carbon transfer: atmosphere->biomass)
The sun!
What type of energy is produced during cellular respiration and *decomposition?
What powers subduction zones?Energy transfer between hot interior and cool exterior
How?
Convectionmovement of molecules in liquids and gases, “flowing”
Coal Formation?Plants that died millions of years ago*Pressure by sedimentary rocks
video
http://video.google.com/videoplay?docid=-7538120906762340500#