Water makes up about 70% of a cell's weight and is essential for many cellular functions, including:

* Solvent: Water dissolves many substances, allowing for chemical reactions to occur.

* Transport: Water carries nutrients and waste products throughout the cell.

* Temperature regulation: Water helps to maintain a stable internal temperature.

* Lubrication: Water acts as a lubricant for joints and other tissues.

While other inorganic substances like salts and minerals are important, water far surpasses them in terms of abundance within a cell.