davehaas at nospamprodigy.net
Tue Sep 28 18:31:36 EST 1999
Is it possible for plants to "actively transport" water? Esau makes the
statement that water may be actively transported in certain secretory
structures. I had always thought that water was one thing that couldn't
be actively transported. Somewhere back in time I had acquired this
idea. Now. I realize that there is not a molecular pump for water like
there is for various ions, but if you define active transport as simply
using ATP to move something against a gradient shouldn't you be able to
move water out of a cell like contractile vacuoles do in protists.
This brings to mind another question. Why would a plant want to rid
itself of water in the first place? If special cells (hydathodes) have
evolved to release water in guttation there should be some advantage
shouldn't there? Are some plant cell walls unable to hold up under
excess pressure produced by osmosis. Anyone have any info in this area?
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