Nitrogen: Running in Cycles


In the previous assignment, you studied the carbon cycle. In a previous unit, you described the water cycle. Carbon and water are matter. As you learned in the first unit, matter cycles. Nitrogen is another form of matter that cycles. Like water and carbon, nitrogen is essential to life. Also, like water and carbon, its cycles affect you. Therefore it is important that you learn about the nitrogen cycle, how it affects you, and how you affect it.


There are three parts to this assignment. You must complete all three parts to receive credit for the assignment. Be sure to turn in all three parts at the same time. I will not correct partial assignments. THANKS!


1. Describe the nitrogen cycle. Describe how nitrogen goes from the atmosphere to a form usable to plants, how it is used and excreted by animals, and how it returns to the atmosphere. In your description be sure to explain the words:

  • decay
  • denitrification


Write a short paragraph describing at least two ways the nitrogen cycle affects you. Why is nitrogen important to you? How is it used in your body? How is it used in your community? BE SPECIFIC. At least one of the ways you identify must be a way that nitrogen is used in your body.


Identify and describe at least two ways that you and other humans affect the nitrogen cycle. Provide examples of how human activities affect the nitrogen cycle.

The following web sites may be helpful to you:


The Microbial World; The Nitrogen Cycle and Nitrogen Fixation



When you have complete all three parts of the assignment, label it, put your name in it, and submit it to me.


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