oxygen uptake at night

Jon Monroe monroejd at jmu.edu
Mon Jun 25 12:02:42 EST 2001

Hi Plant-eders,

This is a question from my colleagues who are revising our first-year
bio course that I mentioned earlier.  One part of the course is on
acquiring molecules/energy necessary for life.  The molecule in question
is oxygen.

Oxygen that is produced by plants during the day certainly gets out of
C3 plants through stomata, but how does it get in at night if the
stomata are closed?  Most texts focus on the fact that the affinity of
cytochrome oxidase for O2 is very high and that the level of O2 in the
atmosphere is not likely to be limiting unless the tissues (e.g. roots)
are flooded.  They also discuss internal air spaces that allow O2 to
easily diffuse through most thick tissues.  Is the amount of O2 consumed
at night so much less than the amount inside the cuticle that it doesn't
really matter?  Because O2 is nonpolar can it get through the cuticle?

Many thanks in advance! 


 Jonathan D. Monroe                 Associate Professor 
 Department of Biology, MSC 7801   office: 540-568-6649 
 James Madison University             fax: 540-568-3333 
 Harrisonburg, VA 22807         email: monroejd at jmu.edu 


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