Final answer:
The central vacuole's membrane, called the tonoplast, consists of a single phospholipid bilayer. It regulates water flow and manages turgor pressure, which supports the plant's structure.
Step-by-step explanation:
The central vacuole in plant cells is surrounded by a membrane known as the tonoplast. This membrane consists of a single phospholipid bilayer that is responsible for controlling the flow of materials, particularly water in and out of the vacuole. The ability of the central vacuole to expand and contract is crucial for maintaining turgor pressure within the cell, which in turn supports the plant's structure. Additionally, it stores various substances, including cell sap, enzymes, ions, and at times, toxic byproducts to deter herbivory.