Question

How do stomata open & close?

Answer 1

Stomata are pores on leaves that let gases in and out between the leaf and the atmosphere. There is a pair of Guard Cells on each side of each stoma.

Opening and closure of the stomatal pore are mediated by changes in the turgor pressure of the two guard cells. The turgor pressure of guard cells is controlled by movements of large quantities of ions and sugars into and out of the guard cells. When guard cells take up these solutes, the water potential inside the cells decreases, causing osmotic, water flow into the guard cells. This leads to a turgor pressure increase causing swelling of the guard cells and the stomatal pores open.