A.1.1.5 - Solvent properties of water linked to its role as a medium for metabolism and for transport in plants and animals

Water as a Powerful Solvent

• Water is often called the "universal solvent" because ‌it dissolves a wide variety of substances, due to its polarity.

• When polar or ‍charged substances enter water, water molecules surround them, forming hydration shells.

• The δ− ‍oxygen attracts positive charges; the δ+ hydrogens attract negative charges.

• This separates and ‍suspends the particles, keeping them dissolved.

Hydrophilic

• “Water loving”

• Polar molecules and charged ions are hydrophilic

• Dissolves easily ‍in water

• Ex. Glucose and amino acids

Hydrophobic

• "Water-fearing"

• Non-polar molecules are hydrophobic.‌

• Do not dissolve in water.

• Dissolves in non-polar solvents instead.

• Ex. Fats, ‍oils, cholesterol

Solvent

• Medium that holds solute

Solute

• Particle found in the medium

Water as a Universal Solvent

• Like dissolves like

• Polar molecules dissolve in water

• Many important compounds for life are polar

Metabolism

• Sum of all chemical reactions occurring in an organism to ‍maintain life

• Including reactions that break down molecules for energy (catabolism) and reactions ‌that build molecules for growth and repair (anabolism)