Question

why does plant cell possess large sized vacuole

Answer 1

In plant cells, the vacuoles are much larger than in animal cells. When a plant cell has stopped growing, there is usually one very large vacuole. Sometimes that vacuole can take up more than half of the cell'svolume. The vacuole holds large amounts of water or food.

Answer 2

In mature plants cells, a large vacuole occupying most of the cell space is found. The vacuoles keep the cells turgid and provide them rigidity and support.They even store food material and waste products in plant cells. Vacuoles also help in maintaining the water balance in the cell.
So, the plants posses large sized vacuole.