Here's why:

* Water is the universal solvent: It allows for the transportation of nutrients, waste products, and other molecules within the cell.

* Provides structure: Water helps maintain the shape and volume of the cell.

* Essential for biochemical reactions: Many cellular processes, such as metabolism and protein synthesis, occur in the aqueous environment of the cytoplasm.

While water is the dominant component, cytoplasm also contains other substances like:

* Proteins: Enzymes, structural components, and signaling molecules.

* Lipids: Cell membranes and energy storage.

* Carbohydrates: Energy sources and structural components.

* Inorganic ions: Essential for various cellular functions.

So, while cytoplasm is a complex mixture, water is the foundation on which the rest of the cellular machinery operates.