Guard Cells

The water moves from the inside of the leaf environment to its outside through certain openings known as stomata. The guard cells are kidney shaped cells present in the epidermis. The guard cells are present on either side of the stomata and they manage the size of the stomatal opening. The stomata along with the guard cells are put together called as the “stomatal apparatus”. The inside wall of the guard cell is thicker compared to the other parts of the wall. If the potassium ions move into the guard cell, the water also moves inside the cells due to osmosis. The water movement will make the guard cell to swell and become turgid. The swollen guard cell will allow the stomata to open. The loss of potassium from the guard cells will remove the water from the guard cells and results in plasmolysis of the guard cells. The loss of water makes the stoma to close as the guard cells shrink in their size. The water loss that occurs during transpiration is due to the stomata as the stomata are found responsible for 90percent of water loss by transpiration. Stomata occupies one percent

of the leaf surface.