Water

• 5 importances of water

  hydrolysis + condensation

  transpiration + translocation

  photosynthesis

  solvent

  specific heat capacity + latent heat of vaporisation
• give 3 examples of the importance of water in hydrolysis + condensation

  condensation of beta glucose to make cellulose

  condensation of amino acids into proteins

  hydrolysis of starch into alpha glucose
• outline condensation of beta glucose into cellulose as an importance of hydrolysis + condensation in water

  cellulose cell walls exerts pressure against water inside cell to maintain rigidity/turgidity and prevent bursting.

  turgidity in palisade mesophyll cells increases surface area for photosythesis.
• outline condensation of amino acids into proteins as an importance of hydrolysis + condensation in water

  enzymes e.g. dna polymerase catalyses synthesis of dna needed for growth and repair

  receptors e.g. insulin receptors cause glucose channels to open so glucose can be taken into muscle cells for respiration
• outline hydrolysis of starch into alpha glucose as an importance of hydrolysis + condensation in water

  used in glycolysis (aerobic and anaerobic) to make atp which is needed for:

  active transport in glucose absorption from blood to the gut

  loading sugars into the phloem
• outline the importance of water in transpiration

  water moves into the root by osmosis and is pulled into the transpiration stream due to cohesion tension theory and hydrogen bonds. it travels up the xylem and is released from the stomata.

  water leaving allows CO2 to enter which is needed for photosythesis

  water evaporating maintains stable temperature conditions needed for enzymes
• outline the importance of water in translocation

  mass flow hypothesis states that during translocation sugars and nutrients are dissolved in water and transported to the sinks in the roots. this is important because roots cannot photosythesis so need carbohydrates for respiration for atp synthesis for growth.
• outline the importance of water in photosynthesis

  light energy from the sun causes photolysis of water into hydrogen ions, oxygen, and electrons. the electrons are used to replace those lost during ionisation and excitation in the chlorophyll. electrons travel down the ETC which releases small amounts of energy used to pump H+ against the conc gradient from stroma to thylakoid. this creates an electrochemical gradient so H+ can diffuse through atp synthase.

  atp is needed as energy cant be directly obtained from glucose.

  atp is used for muscle contraction and active transport.
• outline high specific heat capacity and latent heat of vaporisation as an importance of water

  SHC means it requires lots of energy to heat one KG by one degree which allows organisms to maintain optimum temperatures for enzymes and earth to be habitable.

  LHV means a large amount of heat is required to evaporate a small amount of water which allows organisms to regulate body temp without loosing too much water.

  if temp is too high enzymes will denature
• outline solvent as an importance of water

  due to its polarity it can dissolve polar biological molecules which could not transport themselves due to electric charge e.g. NaCl