1. The Nitrogen Cycle How the element nitrogen makes it through the ecosystem

2. The Nitrogen Cycle

3. Description of the Nitrogen Cycle N 2 gas in the atmosphere must be taken in by symbiotic bacteria in the roots of plants (legumes) through nitrogen fixation. Then other bacteria change the nitrogen so it can be taken up by plants. Animals eat plants and get nitrogen. When plants and animals die, bacteria do a process called denitrification which puts nitrogen back in the atmosphere.

4. Vocabulary Nitrogen Fixation: process that bacteria use to take up N 2 gas from the atmosphere. Legume: Plant that puts nitrogen in the soil because it has symbiotic bacteria living in its root nodules. Denitrification: process that bacteria use to return N 2 gas to the atmosphere.

5. Biotic and Abiotic Factors Biotic Factors: –Bacteria –Plants –Animals –Decomposers Abiotic Factors: –Fertilizers add nitrogen to soil –N 2 gas, nitrates, nitrites,

6. Review of a protein Elements: CHONS Monomers: Amino acids Polymers: Polypeptides-- chains of amino acids Functions: Enzymes, structure, transport-- proteins have many functions!

7. Crop Rotation Farmers must rotate crops to make sure the soil contains the proper amount of nitrogen. Usually farmers switch legumes like beans (which give nitrogen to the soil) with other plants like corn/tomatoes which take nitrogen from the soil.