The first electron source for plants was H2S, but now most modern plants use H2O as an electron source.

What is the advantage of using H2O instead of H2S?

  • $\begingroup$ Water can dissolve minerals and nutrients what H2S not can as a gas. $\endgroup$
    – Chris
    Jan 22, 2014 at 6:34
  • $\begingroup$ I would guess the abundance of them is relevant to this. Also toxicity/corrosiveness of hydrogen sulphide. $\endgroup$
    – rg255
    Jan 22, 2014 at 9:21
  • 1
    $\begingroup$ You can look at some articles which hypothesize about early evolution. It is hypothesized that some of these habitats were rich in sulphide (early enzymes also had Fe-S catalytic centres. Some enzymes still do) . So I concur with @GriffinEvo that it is all a matter of abundance. $\endgroup$
    Jan 22, 2014 at 13:10

1 Answer 1


The major reason for this is because H20 can cause hydrogen bonding. Hydrogen bonding is what allows for plants to transport "this electron source" from their roots through their stems an further.

The stronger polarity of H20 also allows for stronger interactions. Such as ionic interactions (not fully bound but 2 polar atoms interacting). This kind of ionic interaction also allows for other types of material interactions such as cohesion and adhesion.

Overall, aside from the discussion of abundance as mentioned above (which is a very good point), it also allowed the plants to grow in directions that were more advantageous (darwinian) for their survival.


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