Guard cells are specialized plant cells that have unique properties and play a vital role in regulating gas exchange. Stomata, small pores on the surface of the leaves, are controlled by these cells. The function of guard cells is to open or close these pores to ensure optimal conditions for photosynthesis, transpiration and gas exchange.
The structure of guard cells is quite distinct from other plant cells, as they are kidney-shaped with an inner thickening of the cell wall known as the lumen. The two guard cells surround the stomatal pore, which facilitates the passage of gases and water in and out of the plant. To control the size of the stomatal pore, the guard cells expand or shrink depending on the water pressure inside the lumen and cell.
One of the essential functions of guard cells is to regulate water loss through transpiration. Water vapor can escape through stomata open on the surface of the leaf. If left open for an extended time, it can cause excessive water loss, leading to dehydration and death. In contrast, if the stomata are closed, the plant may not receive enough carbon dioxide for photosynthesis, which could weaken the plant over time. Therefore, regulating stomata opening through guard cells is crucial for plant survival.
Moreover, guard cells enable the uptake of carbon dioxide and other essential gases required for photosynthesis. When light is in abundance, guard cells absorb energy and facilitate the absorption of carbon dioxide into the stomata. In this way, CO2 is efficiently transported to the chloroplasts, where it is combined with water during photosynthesis.
In conclusion, the significance of guard cells in plant physiology cannot be overemphasized. Their ability to regulate gas exchange, water loss, and protect plant surfaces against extreme temperatures has made them indispensable to plant survival. The importance of guard cells has expanded beyond the scientific community to agricultural research, where techniques are used to improve plant growth and productivity.#16#