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Simple Nitrogen Cycle

Cell Organelles-How nitrogen is recycled
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Middle School Math and Science

The steps of the nitrogen cycle

Our atmosphere is made of 78% nitrogen. We need the nitrogen for our DNA and for proteins.
We can’t just breath in the nitrogen like oxygen but absorb our nitrogen in our food.
  • Nitrogen follows a cycle where it travels from the atmosphere,the soil,animals, and back to the atmosphere.
  • Nitrogen in the atmosphere falls to the earth in rain snow. 
  • Once in the soil, it finds its way to bacteria on the roots of plants.
At the roots, the nitrogen is combined with hydrogen to make ammonia in a process called nitrogen fixation. 
Lightning in the atmosphere also can do this.

Now ammonia is toxic so additional bacteria combines this ammonia with oxygen in a process called nitrification. At this point, the nitrogen is in a form called nitrite.
  • Additional nitrifying bacteria convert this nitrite to a nitrate 
  • At this point, plants can absorb the nitrogen in a process called assimilation.
Not all of the nitrate is absorbed but some goes into bacteria that release the nitrogen to the atmosphere in a process called denitrifying. The nitrogen returns to the atmosphere.

Animals can also absorb nitrogen by eating plants.
Once the nitrogen enters the animal, the animal gets rid of waste when using the bathroom, or dies.

Another type of bacteria and decomposers breaks down the poop or dead animal which contains nitrogen by ammonification and the nitrogen can enter the cycle and the cycle continues.