1. Lesson 18 10/10/17 SWBAT answer an APES FRQ related to biogeochemical cycles
Do Now: MC Questions

2. Do Now Key A E B D

4. 1. Biotic Nitrogen Fixation
Nitrogen gas (N2) and H2 is converted into ammonia (NH3)
Nitrogen fixing organisms: Cyanobacteria and bacteria that live in the roots of legumes (beans, peas)
Bacteria Rhizobium participates in nitrogen fixation
Nitrogen is fixed in cyanobacteria through their heterocysts

5. 1. Abiotic Nitrogen Fixation
Lightning and combustion convert N2 into NO3- (nitrate)
Humans can fix nitrogen through technology that convert N2 into NO3- (nitrate) to be used as fertilizer

6. 2. Assimilation
Producers obtain fixed nitrogen in the form of ammonium (NH4+), ammonia (NH3) or nitrate (NO3-) and assimilate it (take it) into their tissues
Consumers assimilate nitrogen by eating producers

7. 3. Ammonification Producers and consumers die
Nitrogen returned to soil
Decomposers break down dead organisms into ammonium (NH4+)

8. 4. Nitrification
Nitrifying bacteria convert ammonium (NH4+) into nitrite (NO2-) and then into nitrate (NO3-)
Nitrate is usable for producers
Nitrate moves through soil with water by leaching
Negative charge of nitrate (NO3-) does not bind easily to soil particles (also negatively charged)

9. 5. Denitrification Leached nitrates settle in sediment
Denitrifying bacteria convert nitrate (NO3-) into nitrous oxide (N2O) and nitrogen gas (N2)
Nitrogen gas released back to atmosphere

10. Tips for mastering the nitrogen cycle
Make flash cards!
Nitrite (NO2-) is light because it has one less oxygen than nitrate (NO3-)
Ammonium (NH4+) has one more letter and one more hydrogen than ammonia (NH3)

11. FRQ Practice Work silently and independently for 10 minutes on the FRQ
You may use your notes as needed
After 10 minutes you may work through FRQ with your group

12. Homework
Complete FRQ and Reflection