What is the large, central organelle in plant cells filled with fluid called?

The large, central organelle in plant cells that is filled with fluid is called the vacuole. Vacuoles play a crucial role in maintaining the turgor pressure within plant cells, which helps keep the plant rigid and supports its structure. They can store nutrients, waste products, and other substances, and are also involved in the regulation of cell growth and metabolism.

In plant cells, vacuoles are typically much larger than in animal cells, often occupying a significant portion of the cell's interior. This fluid-filled compartment can also contain enzymes and other molecules that contribute to cellular functions. Overall, the vacuole is essential for plant cell homeostasis and plays a vital role in the overall health of the plant.