Thank you for the opportunity to help you with your question!
Guard cells are cells surrounding each stoma. They help to regulate the rate of transpiration by opening and closing the stomata.
Guard cells are able to control how open or closed stomata are by changing shape. They are like an inflatable set of doors that make the opening between the two cells wider or narrower. The guard cells change shape depending on the amount of water and potassium ions present in the cells themselves.
When the guard cells take in potassium ions, water diffuses into the cells by osmosis. Osmosis is the movement of water from an area of low concentration of solute (dissolved substance) to an area of high concentration of solute. When the water enters the cells, they swell and become bowed. This causes the guard cells to bend away from each other, thereby opening the stomata.
Please let me know if you need any clarification. I'm always happy to answer your questions.
Jul 28th, 2015
Did you know? You can earn $20 for every friend you invite to Studypool!