water and inorganic ions

• water is the medium in which all metabolic reactions take place in cells
• water is covalently bonded
• water is a dipole
• water is a polar molecule
• hydrogen bonds form between water molecules
• properties of water:

  • excellent solvent
  • high specific heat capacity
  • high latent heat of vaporisation
  • water is less dense when a solid
  • high surface tension and cohesion
  • acts as a reagent
• polar substances will dissolve in water
• metabolites can be transported efficiently because water is polar
• what is the role of water having a high specific heat capacity in living organisms?

  allows water to be a suitable habitat and means that an optimal temperature can be maintained within cells and bodies
• the presence of many hydrogen bonds gives water a high specific heat capacity
• what is the role of water having a high latent heat of vaporisation in living organisms?

  coolant
• why does water have a high latent heat of vaporisation?

  presence of many hydrogen bonds
• hydrogen bonds allows for strong cohesion between water molecules, which allows columns of water to move through the xylem of plants and blood vessels in animals
• hydrogen bonds also enables surface tension where a body of water meets the air, as the hydrogen bonds occur between the top layer of water molecules to create a film of the body of water
• water is able to hydrogen bond to other molecules like cellulose, this is known as adhesion
• adhesion enables water to move up the xylem due to transpiration
• a cation has a positive charge
• an anion has a negative charge
• an inorganic ions does not contain carbon
• inorganic ions play an important role in many essential cellular processes
• inorganic ions occur in solution in the cytoplasm and body fluids of organisms
• the concentration of certain ions can fluctuate and can be used in cell signalling and neuronal transmission
• concentration of hydrogen ions determines pH
• inverse concentration between the pH value and the hydrogen ion concentration
• changes in pH can affect enzymes structure
• iron ions are essential as they can bind to oxygen
• haemoglobin is the large protein in red blood cells that is responsible for transporting oxygen around the body
• iron ions are also essential as they are involved in the transfer oof electrons during respiration and photosynthesis so they are key to the biological generation of energy
• sodium ions are required of the transport of glucose and aminos acids across cell-surface membranes
• sodium ions are also required for the transmission of nerve impulses
• phosphate ions attach to other molecules to form phosphate groups, essential for DNA, RNA and ATP
• calcium ions is essential in the movement of organisms
• calcium ions will stimulate muscle contraction