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Plants in the bedroom

Steve Casper casper at scripps.edu
Wed Feb 22 09:33:09 EST 1995

In article <3iddr5$51k at umd5.umd.edu>, bwilliam at oyster.smcm.edu (Bill
Williams) wrote:

> In article <3iba7f$p5a at newsbf02.news.aol.com>
> onedolphn at aol.com (OneDolphn) writes:

> Well, no.  Plants, like all aerobic organisms, ALWAYS breathe in oxygen
> and give off CO2:  you got it backwards.  However, when there is enough
> light some parts of the plant (usually the leaves) ALSO "breathe" in
> CO2 and give off oxygen.  Obviously (since plants do grow) the overall
> balance is in favor of photosynthesis (taking in CO2 and giving off
> O2).

Actually, in S & R Plant Physiology, it is stated that CO2 is produced by
the plant during respiration to obtain ATP but that most of the CO2 is
used by the plant rather than released.  I believe the majority of the O2
used by the plant comes from water and not the air.  But you are correct;
when the stomata are open, both gasses enter since there is no
selectivity.  What matters is the local partial pressure of the gasses in
the tissue and that varies with respect to cell type, function,  and
location within the plant.  Overall, more O2 diffuses out of the plant
than CO2.


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