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Name: __________________________________________________ Date: _____________ Period: ______
The Nitrogen Cycle
Directions: Answer the following questions by visiting the website below
http://bcs.whfreeman.com/thelifewire/content/chp58/5802004.html
Introduction
1. Name 3 molecules that require nitrogen.
a. ____________________
b. ____________________
c. ____________________
2. Where is most nitrogen on Earth found? ________________________________________________
3. What percentage of the atmosphere is nitrogen? __________________________________________
4. Which type of organisms can use nitrogen in the atmosphere? _______________________________
Click ANIMATION and then click STEP-THROUGH (1 of 5)
5. Which type of bond holds N2 together? _________________________________________________
Click PLAY then click CONTINUE (2 of 5)
6. What are bacteria called that use N2? ___________________________________________________
7. First, N2 is converted in ___________________.
8. Then, NH4 is converted into ___________ and ___________.
9. Which organisms can use NO2 and NO3? _______________________________________________
10. How do animals obtain their nitrogen? __________________________________________________
Click PLAY then click CONTINUE (3 of 5)
11. In which products do humans convert N2 into NH4 and NO3? _______________________________
12. Where does runoff cause nitrogen to accumulate? _________________________________________
Click PLAY then click CONTINUE (4 of 5)
13. Which three molecules are often created from the remains of dead organisms?
a. ____________________
b. ____________________
c. ____________________
14. What is denitrification?
_________________________________________________________________________________
Click PLAY then click CONTINUE (5 of 5)
15. What percent of useable nitrogen (NH4, NO2, and NO3) is used by life? _______________________
Click CONCLUSION
16. Specifically, what do nitrogen fixers do? ________________________________________________
17. Why is an abundant amount of nitrogen from humans bad? _________________________________
_________________________________________________________________________________
Class Notes:
Why we care: Nitrogen is needed to build ____________________.
Problem: Nitrogen in the atmosphere (N2) is ___________________ by most living organisms.
1. Bacteria in the _______________convert N2 gas into a form that can be used.
2. Bacteria absorb usable nitrogen.
3. Bacteria can then release __________________ as waste into the atmosphere.
4. Producers absorb the usable nitrogen through their ____________________.
5. Primary consumers get nitrogen by eating ____________________. Then it can move up the food
chain.
6. ___________________ obtain nitrogen from the dead and then return it to soil in their waste.
Complete the nitrogen cycle below by labeling each step 1-6.
Bacteria
Bacteria
Usable nitrogen (nitrates)
Bacteria