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    Some Qs:
    - Free living nitrogen fixing bacteria convert nitrogen into ammonia? Is this ammonia used by plants? Or does something happen with it?
    - Exactly what do mutualistic nitrogen fixing bacteria do? Add they related in any way to the ammonia produced above?
    - During nitrification, where does NH4+ come from?
    - What is ammonifjcation? NH3 -> NH4+ AND NH4+ -> NH3 or just one or the other?

    Posted from TSR Mobile

    This is pretty much everything you need to know at sixth form level:

    Nitrogen fixation: Nitrogen fixing bacteria are found in root nodules of leguminous plants (like clover). What these do is they convert the nitrogen gas from the atmosphere into ammonia. This is an example of mutualism because the plants are getting their nutrients from the products of the nitrogen fixing bacteria, and the bacteria are getting their carbohydrates from the plants (somehow).
    Nitrification: this is when Nitrifying bacteria oxidise ammonia into nitrite ions and then into nitrate ions.
    Assimilation: Now, the plants take up the nitrate ions via active transport through their root hair cells. Remember, plants can only take up inorganic compounds like nitrate ions.
    Ammonification: this is where Saprobionts break down plant or animal protein to give ammonia. They use extracellular digestion, by releasing protease enzymes which break down the protein into amino acids. They then remove the amino group from the amino acid and just leaving ammonia as the product. (This can then be used in the nitrification stage again).
    Denitrification: this is where anaerobic Denitrifying bacteria convert nitrate ions into nitrogen gas and release it back to the atmosphere.

    I hope I've helped

    Posted from TSR Mobile
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