What primary cause causes the stomata holes of plant leaves to open and close?

🔑Key Points:
-The opening and closing of stomata are primarily controlled by the swelling and shrinking of guard cells.
-Guard cells are specialized cells located on the leaf epidermis.
-When guard cells take in water, they become turgid and the stomatal pore opens.
-When they lose water, they become flaccid and the pore closes.
-This mechanism allows plants to regulate gas exchange and water loss.
-Other factors such as light, carbon dioxide concentration, and internal plant signals can influence this process.

🔴Additional Information:
-Water availability in the soil can affect the overall turgor pressure in plants, but it is the guard cells that directly control stomatal movement.
-Photosynthesis rates can be influenced by stomatal opening, but they do not directly control the opening and closing.
-Presence of sunlight can signal guard cells to open stomata, but it is still the guard cells' swelling and shrinking that directly causes the movement.