How do guard cells open and close the stomata?

When the cell has plenty of water, it becomes turgid, making the cell swollen. This curves the guard cells away from each other, opening the stomata, and allowing gases to be exchanged for photosynthesis. When too much water leaves, the cell becomes flaccid and relaxes, closing the stomata. They have thin outer walls and thickened inner walls to open and close and are light sensitive, so they close at night to save water. They're adapted for gas exchange and controlling water loss in leaves.