What characteristic of water enables it to participate in a wide range of biological reactions?

• A. Nonpolar molecule
• B. Hydrophobic
• C. Polar molecule
• D. Ionic compound

Answer: (C)

Water’s ability to participate in many biological reactions comes from its polarity. The oxygen atom is highly electronegative, pulling electron density toward itself and creating a bent molecule with partial negative charge on the oxygen and partial positive charges on the hydrogens. This polarity lets water form hydrogen bonds and interact with a wide range of charged and polar substances, making it an excellent solvent and a common participant in reactions. Water can act in hydrolysis, where it adds to bonds to break them, and it is also produced or consumed in condensation processes. If water were nonpolar, it wouldn’t dissolve salts or polar molecules well and wouldn’t readily participate in these reactions; hydrophobic and ionic descriptions refer to other aspects, not water’s defining property. So the characteristic that best describes water here is that it is a polar molecule.