Regulating Stomata...question

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student12
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Regulating Stomata...question

Post by student12 » Sun May 14, 2006 12:26 pm

There are many ways in which stomata is regulated. One of the ways is by converting insoluble starch to solube sugars in the guard cells. This causes an osmotic gradient, and therefore water will travel into the guard cells by osmosis, opening the stoma.

My question: To increase osmotic gradient gradient it must contain dissolved subs tances? How about solids (starch) wouldn't that still increase osmotic gradient?
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Doc44
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Post by Doc44 » Mon May 15, 2006 12:49 am

Smaller particles i.e. molecules in solution will produce a higher concentration of solute thus a stronger hypertonic solution than will large molecules of starch. Therefore water will go into the guard cell at a greater rate than it goes out, thus producing an increase in turgar pressure, thus swelling of the guard cells and opening of the stomate.

Doc44

Check out why a saturated NaCl solution will have a potentially higher osmotic potential than a saturated glucose solution. Keep your EYE ON this one.

student12
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Post by student12 » Tue May 16, 2006 11:31 am

So does starch still cause an osmotic gradient and therefore osmosis will occur?
Because the way i interpret the info in my textbook, what its trying to say is that insoluble starch does not alter osmotic gradient...
But the way you're saying it is that it still does but just at a slower rate. However, if this is so than stomata will eventually open with the starch but just at a slower rate?
Sorry, I am just very confussed on this one.

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Post by SU_reptile » Wed May 17, 2006 9:22 pm

As far as I remember, concentration gradient occurs in solutions. Consequently, as starch is not soluble in water, it hasn't any influence on osmotic flow to the guard cells.
I need to revise that topic and take a closer look at the thing, but I think what I said is true.

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Post by baikuza » Sun Jun 11, 2006 12:39 pm

about the open and close of stomata.
until now, at least 1994, no theory can describe the real mechanism about this.
the last is the effect of Kalium in the guard cell..

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Linn
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Post by Linn » Sun Jun 11, 2006 2:13 pm

SU_reptile wrote:As far as I remember, concentration gradient occurs in solutions. Consequently, as starch is not soluble in water, it hasn't any influence on osmotic flow to the guard cells.
I need to revise that topic and take a closer look at the thing, but I think what I said is true.


sounds right to me :)
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Post by always_love_mother » Sat Jun 17, 2006 4:00 pm

i want to whol kingdom fungi

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