The osmotic expansion of a cell kept in water is chiefly regulated by:

Step-by-step solution

The osmotic expansion of a cell kept in water is chiefly regulated by the cell organelle vacuole is surrounded by the tonoplast layer. A single large organelle constitutes about 20% of cell stores water and macromolecules including ions, sugar, amino acids, proteins and carbohydrates (cell sap) with high osmotic pressure generating turgor pressure.