Why is water often referred to as the 'universal solvent' in biological systems?

• A. Because it can dissolve only nonpolar substances.
• B. Because it cannot form hydrogen bonds with other molecules.
• C. Because its polar molecules can dissolve a wide variety of substances.
• D. Because it is the only liquid found on Earth.

Answer: (C)

Verified step by step guidance

1. Understand the concept of a 'universal solvent': A universal solvent is a substance that can dissolve a wide variety of solutes. In biological systems, water is often referred to as the universal solvent due to its unique chemical properties.
2. Examine the structure of water molecules: Water (H₂O) is a polar molecule, meaning it has a partial positive charge on the hydrogen atoms and a partial negative charge on the oxygen atom. This polarity allows water to interact with and dissolve other polar substances and ionic compounds.
3. Explore hydrogen bonding: Water molecules can form hydrogen bonds with other polar molecules or ions. These bonds are relatively strong and help water break apart solutes into their individual components, facilitating dissolution.
4. Consider the biological significance: In biological systems, water's ability to dissolve a wide variety of substances is crucial for processes like nutrient transport, waste removal, and chemical reactions within cells.
5. Clarify the incorrect options: Water does not dissolve only nonpolar substances; in fact, it dissolves polar and ionic substances more effectively. It can form hydrogen bonds, and while it is abundant on Earth, its role as a universal solvent is due to its chemical properties, not its abundance.