The organelle that takes up the majority of the volume in a plant cell and is used for food and water storage is the vacuole.

Here's why:

* Large Size: Vacuoles are often the largest organelle in plant cells, sometimes taking up as much as 90% of the cell's volume.

* Storage Function: They store water, nutrients, waste products, and pigments. This helps regulate turgor pressure (the internal pressure that helps maintain the plant's structure), and provides a reservoir of essential materials.

* Food Storage: Vacuoles can hold sugars, proteins, and other nutrients, making them important for plant growth and development.

While other organelles like chloroplasts are also important for plant cells, the vacuole is the dominant one in terms of size and storage function.