Nitrogen Fixing Bacteria-- HELP!

[ramin123]

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The AP book says that cyanobacteria are nitrogen fixing bacteria, but then it says it fixes Nitrogen gas to ammonia (NH3)-- why?

I thoght nitrogen fixing bacteria is from nitrogen gas to nitrates.

It further says that NH3 can be used to make nitrogen-containing amino acids.--- Is that true? or is it nitrates?

I thought the whole point of the nitrogen cycle was to derive nitrates from ammonia that WE DON'T WANT??

 

[DDSguyLA]

Ramin jan, NH3 is the direct product of nitrogen fixation bro...

As far as I know Cyanobacterias are able to send nitrogen gas to all the following;
NH3, NO2, NO3

hope this helps

 

[ramin123]

But kaplan shows that the product of nitrogen fixing is Nitrates?

 

[DDSguyLA]

simply put they wont ask you a question like:

what does nitrogen fixing bacteria makes:

NO2
NO3
NH3


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its kinda like this

N2 -> NH3 -> NO2 -> NO3

this is what nitrifying means... so it pretty much does all 3 things but the direct is NH3. but then again, NO2 can be a product of NH3 and NO3 can be a product of NO2.

 

[ramin123]

I thought there were two pathways-- that NH3---> N2---> NO3 & NH3--> No2---> No3

Is that wrong??

 

[PooyaH]

I thought there were two pathways-- that NH3---> N2---> NO3 & NH3--> No2---> No3

Is that wrong??

NH3 could be turned into NO2 or N2 by nitrifying and denitrifying bacteria respectively. Nitrifying bacteria then trun NO2 into NO3- and Nitrogen fixing bacteria make NO3- out of N2.

So you're correct.