Which of the following cells contain plasmodesmata only on one side:
a. epidermis b. pericycle c. XVMS d. a and b e. all of the above
The correct answer and explanation is:
The correct answer is a. epidermis.
Plasmodesmata are microscopic channels that allow for communication between plant cells. They are formed through the fusion of the cell membranes and are typically found in most plant cells, allowing for the exchange of materials such as ions, proteins, and other molecules. In terms of location, plasmodesmata are most commonly found in the cell walls of plant cells.
For the epidermis, which is the outermost layer of cells in a plant, plasmodesmata are typically only present on one side of the cell. This is because the epidermis has a protective role, and its cells are often tightly sealed to form a barrier against environmental stressors. In these cells, plasmodesmata usually form connections with adjacent cells but are absent from the side facing the external environment, where a waxy cuticle may also be present to prevent water loss.
In contrast, cells in the pericycle (a tissue layer in roots), xylem vessel members (XVMS), and other plant tissues typically have plasmodesmata in various orientations to facilitate intercellular communication. The pericycle is involved in the formation of lateral roots, and its cells are actively involved in growth and communication with other tissues. Likewise, xylem cells, which conduct water and minerals, also have plasmodesmata in their walls, especially during early development, though these structures may disappear as the cells mature into vessels.
Thus, the unique characteristic of the epidermis is that plasmodesmata are found primarily on one side of the cells, while other tissues have them in multiple directions to support their specific functions.