Which best explains why blood and the cytoplasm of cells are mainly composed of liquid water?

• A. Water is the only liquid found naturally on Earth.
• B. Water's polarity allows it to dissolve a wide variety of substances necessary for cellular processes.
• C. Water molecules are nonpolar and do not interact with other molecules.
• D. Water cannot form hydrogen bonds, making it chemically inert.

Answer: (B)

Verified step by step guidance

1. Understand the properties of water: Water 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 many substances, making it an excellent solvent.
2. Recognize the importance of water's solvent properties: In biological systems, water's ability to dissolve a wide variety of substances is crucial for transporting nutrients, ions, and molecules within cells and throughout the body.
3. Eliminate incorrect options: The statement 'Water is the only liquid found naturally on Earth' is incorrect because other liquids, such as liquid methane, exist naturally in certain environments (e.g., on Titan, a moon of Saturn).
4. Evaluate the statement 'Water molecules are nonpolar and do not interact with other molecules': This is incorrect because water is polar and interacts strongly with other polar molecules and ions through hydrogen bonding and dipole interactions.
5. Assess the statement 'Water cannot form hydrogen bonds, making it chemically inert': This is also incorrect because water forms hydrogen bonds, which are critical for its unique properties, such as high heat capacity, surface tension, and solvent abilities. The correct explanation is that water's polarity allows it to dissolve a wide variety of substances necessary for cellular processes.