Statement-I: During stomatal opening there is relative change in turgor pressure of guard cells.

Statement-II: Turgor pressure of guard cells is high while stomata are open.

The immediate cause of the opening or closing of stomata is a change in the turgidity of the guard cells. The inner wall of each guard cell, towards the pore or stomatal aperture, is thick and elastic. When turgidity increases within the two guard cells flanking each stomatal aperture or pore, the thin outer walls bulge out and force the inner walls into a crescent shape. The opening of the stoma is also aided due to the orientation of the microfibrils in the cell walls of the guard cells.