1. Nitrogen Cycle Notes 11/8/18 Entry 23
Key Points:
The Nitrogen Cycle
Fixation
Nitrification
Assimilation
Ammonification
Denitrification

2. 1. The Nitrogen Cycle
A. Nitrogen moves between plants, animals, bacteria, the atmosphere (the air), and soil in the ground.
Five Main Parts
Fixation
Nitrification
Assimilation
Ammonification
Denitrification

3. 1. The Nitrogen Cycle
C. The most important helper of the cycle is bacteria. 1. Bacteria helps the nitrogen change between forms so it can be useable to plants and animals. 2. Bacteria gives nitrogen the ability to be absorbed by plants; then, animals get nitrogen from plants

4. 2. Fixation
A. Fixation is the first step in the process of making nitrogen usable by plants. B. Here, bacteria change nitrogen (N2) into ammonium (NH4).

5. 3. Nitrification
A. The process by which ammonium (NH4) gets changed into nitrites (NO2), and then into nitrates (NO3) by bacteria. B. Nitrates are what the plants can then absorb.

6. 4. Assimilation
A. Process of how plants get nitrogen (N2). B. Plants absorb nitrates (NO3) from the soil into their roots.

7. 4. Assimilation
C. Once absorbed in the plant, the nitrogen (N2) gets used in amino acids, nucleic acids, and chlorophyll.
Chlorophyll

8. 5. Ammonification
A. This is part of the decaying process. B. When a plant or animal dies, decomposers turn the nitrogen (N2) back into ammonium (NH4) so it can re-enter the nitrogen cycle.

9. 6. Denitrification
Extra nitrogen in the soil gets put back out into the air.
B. Bacteria in the soil perform denitrification.