How would photosynthesis work if it used ammonia as a solvent and was nitrogenic as opposed to water-based oxygenic photosynthesis? Ammonia is a basic solution so it might need some other kind of protein based on another element so it doesn't denature. But what would the respiration equation look like for this creature? This organism is going to be anaerobic because it probably doesn't use oxygen (reducing atmosphere). Can someone sketch out this photosynthetic organism?

  • $\begingroup$ Ammonia is not a "solution", unless you mean a solution of ammonia in something else. (And our proteins cannot coexist with pure liquid ammonia. As far as we can tell, any kind of protein cannot coexist with pure liquid ammonia. The organisms in an ammonia world cannot be made of proteins; you must find some other versatile structure which can coexist with pure ammonia.) (And why assume that the oxygen released from photosynthesis comes from water? Quantitatively, it comes from the CO2 -- for every carbon atom incorporated into the sugary product, one molecule of oxygen is released.) $\endgroup$
    – AlexP
    Jul 25, 2021 at 22:37
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    $\begingroup$ There cannot be any oxygen because liquid ammonia is not at all compatible with oxygen, otherwise, the hydrogen will bond with the oxygen instead creating water. Liquid ammonia is the biosolvent on this planet, with virtually no water, no oxygen. I know our proteins cant exist in liquid ammonia, that's why part of my question involves solving this problem. $\endgroup$ Jul 25, 2021 at 22:55
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    $\begingroup$ I was going to reuse my cyanide answer from this question worldbuilding.stackexchange.com/questions/120762/… but really I think it is the same question as yours. I was never able to figure out the enthalpy for the reaction and if you can I would much appreciate it. $\endgroup$
    – Willk
    Jul 26, 2021 at 1:15
  • $\begingroup$ We accept real world questions in the context of building your world, but this feels like it might get a better response from Chemistry. Especially if you're asking for equations. Do you really need that level of detail? $\endgroup$
    – JBH
    Jul 26, 2021 at 2:42
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    $\begingroup$ @Willk I am a little confused about the photosynthetic reaction scheme you provided: N2 + CH4 + energy --> HCN + NH3. How do you get nitride rubber? Do you just take the product (HCN + NH3) and get it? I feel like the sugar you get should be from the plant and thus included in the product. Secondly, why does the autotroph absorb the atmospheric compounds and expel ammonia and hydrogen cyanide? Shouldn’t the autotroph take in ammonia and expel N2 and CH4 similar to photosynthesis on earth. I get: 3NH3 + 2C4H2 (Diacetylene) + light --> C7H9N (nitrile rubber) + N2 + CH4. What am I doing wrong? $\endgroup$ Jul 26, 2021 at 8:11


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