Question

What causes the opening and closing of stomatal pore and how?

Answer 1

During transpiration the movement of potassium ions in and out of the guard cells causes the opening and closing of stomata. During day time when light falls on the leaves, the starch present in them absorbs the light. Due to this formation of malice acid takes place in the guard cells.

Answer 2

The opening and closing depends upon the turgor pressure in the guard cells. The swelling of guard cells due to absorption of water causes opening of stomatal pores while shrinking of guard cells closes the pores. Opening and closing of stomata occurs due to turgor changes in guard cells

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