Guard Cells in Plants

Guard cells are specialized cells found in the epidermis of plant leaves and stems. They play a crucial role in regulating gas exchange and controlling the opening and closing of stomata, small pores on the surface of plant tissues. Stomata allow for the exchange of gases, such as oxygen and carbon dioxide, as well as the release of water vapor.

Statement: Plasmodesmata are absent in guard cells (Option D)

Explanation:
Plasmodesmata are microscopic channels that connect neighboring plant cells, allowing for the transport of molecules, nutrients, and signals between cells. These channels traverse the cell walls and connect the cytoplasm of adjacent cells. Plasmodesmata are essential for cell-to-cell communication and transport in plants.

The statement that plasmodesmata are absent in guard cells is true. Guard cells are unique in that they have specific adaptations that allow them to function efficiently in regulating stomatal opening and closing. These adaptations include specific modifications to their cell walls and the absence of plasmodesmata.

Guard Cell Adaptations:
1. Thick Cell Walls: Guard cells have thickened cell walls that are unevenly thickened around the stomatal pore. This uneven thickening allows for flexibility and bending of the cell walls during stomatal movement.

2. No Vacuoles: Guard cells have a reduced or absent central vacuole. This absence of vacuoles allows for better control over the turgor pressure and volume changes within the cells, which are essential for stomatal movement.

3. Absence of Plasmodesmata: Guard cells do not possess plasmodesmata. This absence restricts the direct communication and transport of molecules between guard cells and neighboring cells. It allows guard cells to function autonomously and respond rapidly to environmental cues, such as light, temperature, and humidity.

In summary, the statement that plasmodesmata are absent in guard cells is true. Guard cells have unique adaptations, including thick cell walls, the absence of vacuoles, and the lack of plasmodesmata, which enable them to regulate stomatal opening and closing efficiently.