Correct Option
The correct option isPlant cells have a rigid cell wall that exerts pressure against the swollen cell.
Explanation
Plant cells are distinguished from animal cells by the presence of a rigid outer boundary known as the cell wall. This structure, composed primarily of cellulose, lies outside the plasma membrane and provides mechanical support and protection against osmotic pressure variations.
Option Analysis
- Plant cells have a rigid cell wall that exerts pressure against the swollen cell. is Correct. When a plant cell is placed in a hypotonic solution (dilute solution), water enters the cell through osmosis. The cell swells, and the cytoplasm builds up pressure against the cell wall (turgor pressure). The rigid cell wall exerts an equal and opposite pressure (wall pressure) against the expanding cell contents. This mechanical resistance prevents the cell from bursting, allowing it to withstand significant changes in the surrounding medium.
- Plant cells have larger vacuoles that absorb all excess water. is Incorrect. Although plant cells possess large central vacuoles that store water and contribute to turgidity, the vacuole itself cannot prevent the cell from bursting. It is the external constraint provided by the cell wall that contains the expansion.
- Plant cells have stronger plasma membranes. is Incorrect. The plasma membrane in plant cells is a flexible lipid bilayer similar to that in animal cells. It lacks the structural rigidity required to withstand high internal pressure without the support of the cell wall.
- Plant cells do not perform osmosis. is Incorrect. Osmosis is a fundamental process in plant cells, essential for water absorption by roots and maintaining turgor pressure. The claim that they do not perform osmosis is factually wrong.
Key Takeaway: The rigid cell wall allows plant, fungal, and bacterial cells to maintain structural integrity in hypotonic environments by counteracting turgor pressure, whereas animal cells, lacking this wall, are prone to lysis (bursting).