C3-plant and C4-plant

philcorbett philcorbett at ntlworld.com
Mon Jul 30 07:12:09 EST 2001


We also need to know the growing media. Moist warm organic compost would be
a source of CO2 and possible pathogens.
Phil.
"Cereoid*" <cereoid at prodigy.net> wrote in message
news:yi_87.4908$2v1.1004094687 at newssvr17.news.prodigy.com...
> This is not some hypothetical "thought experiment".
>
> This is either some real experiment using actual plant species or a pure
> hoax.
>
> Do you see the difference?
>
>
> David Kirschtel <kirschte at msu.edu> wrote in message
> news:3B6462E0.AD841BBD at msu.edu...
>
>
> Cereoid* wrote:
> >
> > Pure speculation.
> >
> > Its worthless without one being able to refer back to the actual
> experiment
> > itself, if it really existed, or being able to duplicate it.
> >
> > We still do not know where was it published or which species were used.
> >
>
> Sorry Cereoid, we need none of the above. Einstein's greatest
> contribution to science was the _Gedanken_Experiment_ ("Thought
> Experiment") and that's sufficient for our purposes here. So, let's
> continue....
>
> The problem is, paradoxically, O2 concentration not CO2 and is the
> result of photorespiration. RUBISCO has an affinity for O2 as well as
> CO2. If O2 is bound to RuBP then it is oxidized, with CO2 being lost
> from the Calvin-Benson cycle. This can result in a 20-50% loss of fixed
> C from the plant in "normal" conditions.
>
> This is considered to be the selective force for the evolution C4
> photosynthesis. C4 plants have spatially separated the O2-producing
> Light Reactions from the C-fixing Dark Reactions of photosynthesis and
> thus minimized/reduced the C-fixing inefficiency of photorespiration.
>
> So, in a sealed container with (presumptively) high O2 concentrations
> the C3 plant would starve to death for lack of carbon. Meanwhile, the C4
> plant would be "cannibalizing" the CO2 being lost from the C3 plant as a
> result of photorespiration.
>
>
> Original Question:
> > I´ve recently heard of following experiment:
> > If you cultivat a C3-plant and a C4-plant together in an airtight
> > glassy container, the C3-plant will die after a short period of time.
> > Could anybody explain to me for what reason / reasons the C3-plant
> > will die.
>
>
> --
> ------------------------------------------------------------------------
>   David Kirschtel, Ph.D. * kirschte at pilot.msu.edu * 517.432.0898
>     112 N Kedzie Lab * Mich State Univ * E Lansing, MI * 48824
>  First Year Online/Biology http://lecture.lite.msu.edu/~bio/fyol/
>          [after 17 Sept: Biology Program, Hitchcock Hall,
>        Univ. of Washington, Seattle WA, 98150 206.543.9120]
>
>





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