1. Nitrogen Cycle
TEKS 12 a

2. Objectives
Analyze the flow of energy through the Nitrogen Cycle and Phosphorus.
Analyze changes caused by human and natural occurrences in these two cycles.

3. What is Nitrogen?
Nitrogen is a chemical element. Look at the periodic table at the front of the room.
What group is carbon in? ________
What is the atomic mass? ________
How many protons? __________

4. What is Nitrogen? Where can we find nitrogen?
Since it is odorless, colorless and tasteless, we often don’t realize that nitrogen is ALL around us.
Raise your hand if you know what percentage of the air around you is Nitorgen….

5. Did you guess it??
78% 75

6. Nitrogen Cycle Nitrogen is important to all life!!
From the depths of the ocean ….

7. Nitrogen Cycle
To the atmosphere around us…

8. Nitrogen Cycle
We know Nitrogen is found in the air, but where are some other places we can find it?
In living Tissue
In proteins
In chemicals (ex: ammonia, nitric acid)

9. What is that process called?
Nitrogen Cycle
Nitrogen in the atmosphere cannot be used by most organisms. It has to go through a special process first.
What is that process called?

10. What does this mean?? Nitrogen Cycle
Nitrification- Changing NH4 into NO2 or NO3
What does this mean??
Bacteria + Ammonia
Usable Nitrogen for Plants and Animals

11. Nitrogen Cycle Plants need nitrogen to grow, develop and produce seed.
The main source of nitrogen in soils is from organic matter.
Organic matter can be plant and animal residues.

12. Nitrogen Cycle
The nitrogen in organic matter is largely in organic forms that plants cannot use.
Based on what you have learned so far, what process has to happen before plants can use the nitrogen?
Nitrification….

13. Bacteria found in soils convert organic forms of nitrogen to inorganic forms that the plant can use!
Nitrogen is taken up by plant roots and combined into organic substances in the plant, such as enzymes, proteins and chlorophyll.

14. Nitrogen Cycle
When the plants die, that organic material goes back into the soil and it may be converted again!
How does nitrogen leave the soil other than through plants?

15. Nitrogen Cycle
Denitrification- Bacteria change nitrate in the soil to atmospheric nitrogen, which joins the atmosphere.
Runoff Carries the nitrogen in fertilizers and manure and the nitrogen in the soil into our rivers and streams -- a concern for water quality.

16. Nitrogen Cycle
Another way nitrogen enters the cycle is as inorganic nitrogen from the atmosphere and factories.

17. Make a thinking map to show the steps of the nitrogen cycle
You may include: pictures, labels and descriptions.
The next slide will help you…

18. Nitrogen Cycle
Cyanobacteria & Rhizobium take nitrogen from air (nitrogen fixation)
Convert Nitrogen Gas into ammonia
Nitrifying bacteria in soil change ammonia into nitrates
Plants absorb and use nitrates to make proteins
Consumers eat plants and get proteins containing nitrogen
Decomposers break down organic material and release nitrogen to the air (called ammonification)
Anaerobic bacteria in soil release nitrogen from nitrates into the air (called denitrification)

19. Phosphorus Cycle