Final answer:
A malfunctioning cell wall is likely responsible for a plant cell not maintaining its shape properly. The cell wall provides support and interacts with turgor pressure to keep the cell rigid, while the plasma membrane regulates water flow and prevents lysis or plasmolysis.
Step-by-step explanation:
Plant Cell Structure and Function
If a plant cell is not able to maintain its shape properly, the part likely to be malfunctioning is the cell wall. The cell wall provides the structural support necessary for the plant cell to maintain its shape. When functioning properly, the cell wall interacts with turgor pressure, which is generated by the influx of water into the cell, creating rigidity in the cell. If a plant does not receive sufficient water, the result is a loss of turgor pressure leading to wilting. Conversely, living cells with secondary cell walls containing lignin remain rigid even after death, providing structural integrity. This demonstrates the essential role of the cell wall in maintaining plant cell shape and overall plant structure.
In addition to the cell wall, the plasma membrane is also crucial as it is involved in osmoregulation to prevent cell lysis or plasmolysis. When a plant is in a hypertonic environment, water leaves the cell, resulting in plasmolysis where the membrane detaches from the cell wall. Plants with only a primary cell wall, which lack the reinforcement of secondary walls, are more susceptible to losing structural integrity when stressed by factors like gravity or the wind. Thus, the correct functioning of both the cell wall and plasma membrane is critical for plant cell shape maintenance.