Water

• Biological Importance of Water

  Medium for all metabolic reactions in cells.
• Water Composition


  Composed of hydrogen and oxygen atoms.
• Covalent Bonding in Water


  One oxygen atom shares electrons with two hydrogens.
• Electronegativity in Water


  Oxygen attracts electrons more than hydrogen.
• Dipole


  Separation of charge in polar molecules.
• Polar Molecule


  Molecule with distinct positive and negative ends.
• Hydrogen Bonds


  Weak bonds between positively and negatively charged regions.
• Properties of Water

  High specific heat, solvent, cohesion, and adhesion.
• Universal Solvent


  Water dissolves many ions and polar substances.
• Specific Heat Capacity


  Energy to raise 1 kg of water by 1°C.
• Water's Specific Heat Capacity


  4200 J/kg°C, prevents temperature fluctuations.
• Latent Heat of Vaporisation


  Energy needed to evaporate water.
• Cooling Effect of Evaporation


  Small water loss cools organisms significantly.
• Cohesion


  Attraction between water molecules due to hydrogen bonds.
• Adhesion


  Water's attraction to other substances, like cellulose.
• Xylem Function


  Transports water in plants via cohesion.
• Surface Tension


  Film created by hydrogen bonds at water's surface.
• Metabolite Transport


  Water facilitates efficient transport of dissolved substances.
• Thermal Energy Absorption


  Water absorbs heat without significant temperature change.
• Regulatory Role of Water


  Maintains constant body temperature in organisms.
• Transpiration


  Evaporation of water from plant leaves.