1. THE NITROGEN CYCLE

2. Importance of Nitrogen in amino acids (building blocks of proteins) in nucleic acids (ex. DNA)

3. Atmospheric Nitrogen 70% of the atmosphere is nitrogen (N 2 ) atmospheric nitrogen is not useable by most organisms bacteria are important in making nitrogen available to other organisms

4. Nitrogen Fixation nitrogen fixing bacteria combine N 2 and H 2 to make ammonium (NH 4 + ) live in roots of plants ex. legumes, clover, alder in a symbiotic (mutualistic) relationship plants and soil bacteria use ammonium ions (NH 4 + )

5. lightning can convert N 2 in the atmosphere to nitrate

6. Nitrification other soil bacteria use the NH 4 + to make nitrite (NO 2 - ) and nitrate (NO 3 -) plants use the nitrate to make nucleic acids and amino acids excess stays in the soil or ends up in rivers and lakes as sediment

7. Proteins plants make proteins, which are eaten by consumers consumers use the plant amino acids to make their own proteins

8. Decomposition decomposers break down proteins in dead organisms into ammonia and nitrate in the soil

9. Denitrification denitrifying bacteria convert ammonia and nitrate in the soil back into atmospheric N 2 to complete the cycle

10. Human Influences fertilizers contain nitrates

11. fertilizer runoff from farms can enter waterways and cause excess algal growth and decay (eutrophication)

12. burning fossil fuels produces NO and NO 2 which contribute to acid rain

13. Assignment 4.3 p.95# 1,3, 7,8.9.10,11, 17