Water (Cambridge International IGCSE Biology)

Water as a solvent

Spec point — 3.1.3 · Describe the role of water as a solvent in organisms with reference to digestion, excretion and transport

• Water is important for all living organisms as many substances are able to dissolve in it (it is a solvent)

• This makes it incredibly useful and essential for all life on Earth

• Water is important as a solvent in the following situations within organisms:

  • Dissolved substances can be easily transported around organisms - eg xylem and phloem of plants and dissolved food molecules in the blood
  • Digested food molecules are in the alimentary canal but need to be moved to cells all over the body - without water as a solvent this would not be able to happen
  • Toxic substances such as urea and substances in excess of requirements such as salts can dissolve in water which makes them easy to remove from the body in urine
  • Water is also an important part of the cytoplasm and plays a role in ensuring metabolic reactions can happen as necessary in cells

Water as a solvent