autotrophic or heterotrophic

[ktran17]

Are nitrogen-fixing bacteria heterotrophs or autotrophs? I thought nitrogen-fixing bacteria were a type of chemoautotrophs since nitrogen isnt exactly an organic substance.. However cliff's says other wise

Cliff- "Nitrogen-fixing bacteria are heterotrophs that fix nitrogen"

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[mario0923]

Are nitrogen-fixing bacteria heterotrophs or autotrophs? I thought nitrogen-fixing bacteria were a type of chemoautotrophs since nitrogen isnt exactly an organic substance.. However cliff's says other wise

Cliff- "Nitrogen-fixing bacteria are heterotrophs that fix nitrogen"

I think you are contradicting yourself...I am not sure if I understand you correctly but If you think nitrogen (I don't know if you mean N2 or NH3) is inorganic compound, then bacteria are heterotroph. autotroph is an organism that synthesizes organic compounds that are its own source of energy. N2 is inorganic and ammonia (the product of nitrogen-fixation) is technically inorganic, so the bacteria that produce ammonia is heterotroph since they do not produce organic compounds. If nitrogen-fixing bacteria do not produce their own source of energy (organic compound) and need to rely on consumption, they are heterotroph

 

[ktran17]

Cliff's defines chemoautotrophs as organisms "that use energy obtained from inorganic substances" and heterotrophs as organisms that "obtain their energy by consuming organic substances produced by autotrophs". I understand this.

However, when i was reading cliff's biological diversity chapter, I got confused when he was explaining this paragraph, "nitrogen-fixing bacteria are heteterotrophs that fix nitrogen. Many of these bacteria have mutualistic relationships with plants; that is, both the bacteria and the host plant beenfit from an interdependent relationship. the bacteria lives in nodules, specialized structures in plant roots" (he doesnt state what type of nitrogen)

My question is, how can something that fixes an inorganic substance be a heterotroph. I felt like cliff's was contradicting himself and thats why I posted the question 🙂

Is he implying that the bacteria fixes nitrogen, but actually consumes products produced by it's host, in this case (the plant)?

 

[GoBlue24]

Cliff's defines chemoautotrophs as organisms "that use energy obtained from inorganic substances" and heterotrophs as organisms that "obtain their energy by consuming organic substances produced by autotrophs". I understand this.

However, when i was reading cliff's biological diversity chapter, I got confused when he was explaining this paragraph, "nitrogen-fixing bacteria are heteterotrophs that fix nitrogen. Many of these bacteria have mutualistic relationships with plants; that is, both the bacteria and the host plant beenfit from an interdependent relationship. the bacteria lives in nodules, specialized structures in plant roots" (he doesnt state what type of nitrogen)

My question is, how can something that fixes an inorganic substance be a heterotroph. I felt like cliff's was contradicting himself and thats why I posted the question 🙂

Is he implying that the bacteria fixes nitrogen, but actually consumes products produced by it's host, in this case (the plant)?

Autotrophs (chemoautotrophs and phototrophs) use energy/inorganic compounds to create organic compounds. A nitrogen-fixing bacteria is a heterotroph because it fixes inorganic nitrogen into INORGANIC ammonia (by definition, it cannot be a autotroph) and uses other organic compounds as energy (by definition, it must be a heterotroph). As far as I know, "Fixing" doesn't necessarily mean you convert an inorganic compound into an organic compound. It just means we can use it (for energy, biosynthetic pathways, etc.) since N2 is normally inert.. something like that. So even though "something fixes an inorganic substance", it doesn't necessarily mean it's going to become organic.

 

[mario0923]

Autotrophs (chemoautotrophs and phototrophs) use energy/inorganic compounds to create organic compounds. A nitrogen-fixing bacteria is a heterotroph because it fixes inorganic nitrogen into INORGANIC ammonia (by definition, it cannot be a autotroph) and uses other organic compounds as energy (by definition, it must be a heterotroph). As far as I know, "Fixing" doesn't necessarily mean you convert an inorganic compound into an organic compound. It just means we can use it (for energy, biosynthetic pathways, etc.) since N2 is normally inert.. something like that. So even though "something fixes an inorganic substance", it doesn't necessarily mean it's going to become organic.

exactly!! Goblue24 you are right!
I said you were contradicting yourself because you said nitrogen is an inorganic compound but you don't get why nitrogen-fixing bacteria are heterotrophs. inorganic unreactive nitrogen is N2 and that is converted into reactive inorganic nitrogen usually NH3, NO2, NO3...
organic compounds need carbons, ammonia is not organic compound. ammonia is still "fixed" to be able to react with other molecule for biological pathways. without fixing, N2 is nonreactive, so no reaction.

Hope you now understand 🙂

 

[ktran17]

ahh I get it. It was my fault that I assumed the nitrogen-fixing bacteria fixed nitrogen to an organic compound. Thanks guy. Btw, biological diversity SUCKS!👎thumbdown👎thumbdown👎thumbdown👎thumbdown👎thumbdown👎

Especially when its your second time reading the chapter, but this time I'm also meticulously taking notes, which makes the entire process substantially longer =[.

 

[rogerpc]

Autotrophs (chemoautotrophs and phototrophs) use energy/inorganic compounds to create organic compounds. A nitrogen-fixing bacteria is a heterotroph because it fixes inorganic nitrogen into INORGANIC ammonia (by definition, it cannot be a autotroph) and uses other organic compounds as energy (by definition, it must be a heterotroph). As far as I know, "Fixing" doesn't necessarily mean you convert an inorganic compound into an organic compound. It just means we can use it (for energy, biosynthetic pathways, etc.) since N2 is normally inert.. something like that. So even though "something fixes an inorganic substance", it doesn't necessarily mean it's going to become organic.

That makes sense thank you

 

[rogerpc]

So why is nitrifying bacteria chemoautotrophs?
nitrifying bacteria convert NH4+ to NO2– and NO2– to NO3–.
Aren't all these molecules inorganic?

 

[BTex]

Chemoautotrophs use inorganic energy source instead of the sun. But they still break down organic compounds (CO2, just like plants) with that energy.