Final answer:
The cell retains its shape during plasmolysis because of the structural support provided by its rigid cell wall, even though the plasma membrane shrinks and detaches from the wall.
Step-by-step explanation:
During plasmolysis, a plant cell's plasma membrane contracts and detaches from the cell wall due to the loss of water in a hypertonic environment. However, the cell wall of plant, fungal, and bacterial cells remains intact, which helps the cell to retain its shape despite the shrinkage of the membrane and cytoplasm.
The cell does not completely lose its shape because the rigid cell wall is resistant to significant changes in shape, unlike the flexible plasma membrane. This cell wall provides structural integrity, especially in nonwoody plants where turgor pressure supports the plant. In contrast, animal cells that lack a cell wall, such as red blood cells, will undergo crenation in hypertonic solutions, where they shrink due to dehydration.