Water and inorganic ions

• Explain why water molecules have hydrogen bonds between them

  Water molecules are polar as the Hydrogens are slightly positive and the oxygens are slightly negative due to the uneven distribution of electrons. This creates attractive forces between the molecules called hydrogen bonds.
• State and explain the property of water that can help buffer temperature changes in water

  Water has a relatively high specific heat capacity; It can gain or lose a lot of heat energy without changing temperature;
• Explain 5 properties that make water important for organisms

  It is a metabolite in condensation and hydrolysis reactions, and photosynthesis and respiration; It is a solvent so metabolic reactions can occur and to allow transport of substances; It has a high heat capacity so buffers changes in temperature; It has a large latent heat of vaporisation so provides a cooling effect through evaporation; There is cohesion between water molecules so supports columns of water in plants; There is cohesion between water molecules so produces surface tension supporting small organisms;
• Give the properties of water molecules that are important in the cytoplasm of cells and explain why they are important

  Water is a polar molecule this means it can act as a universal solvent;

  Water is a universal solvent so metabolic reactions occur faster in solution; Water is reactive as it is used/made in hydrolysis and condensation reactions;
• Give the names of inorganic ions and explain their importance in a cell

  Iron ions are found in haemoglobin where they combine with oxygen to carry it round the body. Phosphate ions have a structural role in DNA molecules and store energy in ATP molecules. Hydrogen ions are important in determining the pH of solutions, and are therefore important in the function of enzymes. Sodium ions are important in the transport of glucose and amino acids across plasma membranes.