Other Roles

• Lubricant e.g. synovial fluid in the joints, saliva in the mouth and mucus in the gut
• Hydrostatic Skeleton for plant turgidity, stomatal opening, penis erection and fluid in body cavities
• Protective Cushion e.g. amniotic fluid around the foetus and cerebrospinal fluid
• Reproduction, aquatic organisms release gametes into the water for external fertilisation
• Transparency: Allows light to penetrate (key for photosynthesis), but not all wavelengths of light can penetrate water, blue light penetrates further and deeper water has a lower light intensity
• Reactivity: An important reactant in many chemical reactions; condensation (two molecules are joined by removing water) and hydrolysis (two molecules are split by adding water)
• High Boiling Point (100°C): As lots of energy is required to break the hydrogen bonds, so it remains liquid at room temperatures providing an aquatic habitat for many organisms and a liquid cytoplasm