Inorganic ions and water

• Describe the roles of iron ions, sodium ions, and phosphate ions in cells.

  Iron ions

  1. Haemoglobin associates with oxygen to transport oxygen in the bloodstream

  Sodium ions

  2. Co-transport of glucose or amino acids into cells;

  3. Because sodium moved out by active transport and Na – K pump;

  4. Creates a sodium concentration gradient;

  Phosphate ions

  7. Joins nucleotides in phosphodiester bond

  8. Used to produce ATP;

  9. Phosphorylates other compounds usually making them more reactive;

  10. Hydrophilic part of phospholipid bilayer
• Explain five properties that make water important for organisms

  1. A metabolite in respiration/biological reactions;

  2. A solvent so metabolic reactions can occur

  3. High specific heat capacity so buffers changes in temperature;

  4. Large latent heat of vaporisation so provides a cooling effect through evaporation;

  5. Cohesion between water molecules so supports columns of water in plants;

  6. Cohesion between water molecules so produces surface tension supporting small organisms;
• State and explain the property of water that helps to prevent temperature increase in a cell.

  1. High specific heat capacity;

  2. Buffers changes in temperature;
• Explain properties that make water important for organisms.

  1. A metabolite in respiration/biological reactions;

  2. A solvent so metabolic reactions can occur

  3. High specific heat capacity so buffers changes in temperature;

  4. Large latent heat of vaporisation so provides a cooling effect through evaporation;

  5. Cohesion between water molecules so supports columns of water in plants;

  6. Cohesion between water molecules so produces surface tension supporting small organisms;
• State and explain the property of water that can help to buffer changes in temperature.

  1. water has a relatively high specific heat capacity;

  2. Can gain and lose a lot of heat without changing temperature;
• Water and inorganic ions have important biological functions within cells.

  Give properties of water that are important in the cytoplasm of cells. For each property of water, explain its importance in the cytoplasm.

  1. Polar molecule so acts as a universal solvent;

  2. Universal solvent so metabolic reactions occur faster in solution;

  3. Reactive so takes place in hydrolysis and condensation as well as other reactions in the cytoplasm;