The vacuole is the membrane-bound structure found in the cytoplasm of the cell. Its membrane is called tonoplast, which is thinner than the plasma membrane. The tonoplast facilitates the transport of many ions and other materials against concentration gradients into the vacuole. Hence their concentration is significantly higher in the vacuole than in the cytoplasm. When vesicles, released by the endoplasmic reticulum and Golgi complex, merge, Vacuoles are formed. It contains excretory products, water, sap, and other materials not useful for the cell. In-plant cells, vacuole can occupy up to 90% of the volume of the cell.