Biology B4 (2)

The nitrogen cycle 

the atmospher contains 78% of nitrogen gas.this is very unreactive so it cant be used directly by plants or animals 

nitrogen is needed for making protiens for growth, so living organisms ahve to get it somehow

plants get their nitrogen from the soil, so nitrogen in the air has to be turned into nitrates before plants can use it. nitrogen compounds are then passed along food chains as animals eat plants and each other. 

decomposers break down proteins in rotting plants and animals and urea in animal waste, into ammonia which gos on to form ammonium ions. this returns the nitrogen compounds to the soil.

 nitrogen fixation is the process of turning nitrogen freom the air into nitrogen compounds in the soil…