Answer to Question #151624 in Cell Biology for Aitazaz Shah

Question

Explain how the guard cell/stomata complex opens and closes to conserve water. Include the topics of active transport, passive transport, tonicity, and plant anatomy to explain the process of opening/closing the stomata

Answer 1

Within the epidermis of the organs that regulate gaseous exchange in plants such as the stems and the leaves, there are specialized plant cells known as guard cells. These are found in pairs and have spaces in between them which are called stomatal pores. In cases of intense water scarcity, the guard cells become flaccid whereas, in cases of unlimited water availability, the guard cells become turgid. Whenever charged Chloride and Potassium ions accumulate within the membrane of the guard cells, there is an increased solute concentration which results in a negative potential of water that subsequently gives room for osmosis to occur whereby the water enters the cell. Consequently, the stomatal pores open because the cell becomes turgid. On the flip side, a loss of ions to the surrounding cells, in most cases the Potassium ions, results in loss of water from the guard cells via osmosis and this leads to the closing of the stomatal pores.