In biological systems, water is used in osmosis, metabolic reactions and to carry material around the body.

• A. Water is used in osmosis and to hydrolyze fats.
• B. Water is used only as a solvent in chemical reactions.
• C. Water is used to cool surfaces during industrial processes.
• D. Water is used in osmosis, metabolic reactions and to carry material around the body.

Answer: (D)

Water has several essential roles in biology: it is the universal solvent that allows ions and molecules to dissolve and interact; it is directly involved in metabolic reactions, such as hydrolysis where water breaks bonds, and in transport processes that move substances around the body via blood, sap, or cytoplasm. Osmosis—the movement of water across membranes in response to water potential differences—is foundational to maintaining cell turgor, fluid balance, and overall physiology. Because the statement lists all three major roles—osmosis, participation in metabolic reactions, and transport around the body—it best reflects how water functions in living systems. The other options miss one or more of these key roles: water is not limited to being only a solvent, nor is it about cooling industrial processes, and while it participates in some hydrolysis, that alone does not capture its broad biological importance.