Water (Cambridge (CIE) IGCSE Biology): Revision Note

Water as a solvent

• 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 (opens in a new tab) 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