NITROGEN CYCLE the BIG IDEAS
Nitrogen is an important element in ____________ compounds such as __________, DNA, &
chlorophyll. Nitrogen is the most _________________ gas in the atmosphere. It cycles from the
_________________ to ______________ ____________ & back to __________________. Most living
organisms cannot use N2 in gas form, therefore living things get ___________ ___________from
__________.
NITROGEN CYCLE…1,2,3…
1. Living organisms cannot use simple atmospheric nitrogen molecules (N2).
2. Living things can take it in as a nitrate (NO3-).
3. A Nitrate is formed when nitrogen is combined with oxygen. This process is called nitrogen
____________________. (it’s a southern thang!)
4. Nitrogen-fixing bacteria live on root nodules of _________________ & convert the gaseous
________________ to ammonia (NH4) then to _______________ (NO2 or NO3).
5. Examples of legumes: clover, peas, soybeans & alfalfa.
6. Plants use ______________ to make proteins. Animals only take in nitrogen by consuming producers
or _____________________.
7. Nitrogen flows through the __________ __________ as animals eat plants & animals eat other
animals.
8. During _____________________, nitrogen compounds are released. Bacteria will break down
ammonia to nitrogen & oxygen & release ________________ back to soil and atmosphere.
9. Some aquatic bacteria/microbes and __________________ can also change nitrogen to nitrates.
1.
2.
7.
3.
4.
9.
8.
10.
14.
11.
12.
15.
5.
16.
13.
6.
*nitrifying microbes(NH3)
legumes
nitrates
consumers
ammonification
*soil NH3 (nitrate)
living organisms
*NH3 used by plants
* lost to marine sediment
abundant
usable NH3
*(NH4)dead organisms/waste
nitrogen cycle
organic
*Atmospheric Nitrogen
*plant/animal protein
*lightning
soil microbes/bacteria
*nitrogen-fixing microbes
*artificial fertilizers
*dead organisms/waste
*Volcanic activity
*plant/animal protein
proteins
nitrogen
atmosphere (X2)
fixation (“fixin”)
nitrogen compounds
N2 (X2)
NH3
*blue-green algae in ocean
soil (NH3) nitrates
* ammonium salts (NH4)
*denitrifying bacteria/microbes(NH2)
producers