1. 1. What is Nitrogen?  N makes up about 78% of our atmosphere.  N in the atmosphere it is mostly in the form of ______, which is a compound that plants and animals cannot use.  The process of converting N into compounds that can be used by plants and animals is called the ______________________. N2N2 Nitrogen Cycle

2. 2. Why we care about nitrogen… N is an essential component of _____________________. The building blocks of life. DNA, RNA and Proteins

3. 3. How does atmospheric N (N 2 ) get changed into a form that can be used by most living organisms? The Nitrogen Cycle (it must be ‘fixed’)! Nitrogen Cycle (1) Nitrogen Fixation (2) Ammonification (3) Nitrification (4) Denitrification

4. 4. Nitrogen Fixation ___________________ is the process in which the N 2 compound in the atmosphere breaks and combines with other compounds. The N is _________ when it combines with ______________ or _______________. N N H N HH N2N2 Nitrogen Fixation “fixed” hydrogenoxygen Ammonia (NH 3 ) Nitrous Oxide (N 2 O)

5. Check for Understanding What is ‘unusable’ nitrogen called? What must happen to it before it is available for life? What two elements are added to N during fixation?

6. 5. Three ways to “fix” N  Main process: Special ____________ convert the N gas (N 2 ) to ammonia (NH 3 ), which only ________ plants can use (peas, beans).  _________________ strikes convert N 2 to N 2 O or NO 3.  Industrial production. ____________ manipulation turns N 2 into NH 3 (Fertilizer) bacteria some Lightning Chemical

7. 6. Ammonification _____________________ - After all the living organisms have used the ___________________, decomposer bacteria convert the N to _______________. N H H H Ammonification organic nitrogen ammonia Bacteria Ammonia Organic Nitrogen (proteins)

8. 7. Nitrification _______________ is the process that converts ammonia (NH 3 ) into nitrites (NO 2 ) and nitrates (NO 3 ) which ____ plants _______ use. Note: Ammonia comes from ______ N fixation and ammonification 8. How is it done? _____________________ N N N H H H O O O OO Nitrification most can Both Bacteria!

9. 9. Denitrification _______________: Process in which N compounds _____________________ into atmospheric N (N 2 or N 2 O). The main process is performed by _____________________ in the soil. It can also happen by _____________ fossil fuels. N2ON2O NO 3 N2N2 Denitrification convert back bacteria burning

10. Check for Understanding What are the 3 ways to fix N? What process converts ammonium or ammonia Into nitrates and/or nitrites? What process takes fixed N and returns it back to atmospheric N?