What function do the specialised cell walls in guard cells serve?

The specialised cell walls in guard cells are designed to allow the cells to change shape when they become turgid, which is when they fill with water. When guard cells take in water, their inner walls are thicker than their outer walls, causing them to bulge and push apart. This action creates an opening called a stoma, which facilitates gas exchange, allowing carbon dioxide to enter the leaf for photosynthesis and oxygen to exit.

The ability of the guard cells to manipulate the size of the stomatal opening is crucial for regulating water loss through transpiration as well as maintaining the balance of gases within the plant. When the guard cells are turgid, they help open the stomata, whereas when they lose water and become flaccid, the stomata close, preventing excessive water loss.

Thus, the correct function of the specialised cell walls in guard cells is their role in enabling the cells to push apart, which is essential for the control of gas exchange and water conservation in the plant.