2.4 Water and it's Functions

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AS - Level Biology (2 - Nucleic Acids) Mindmap am 2.4 Water and it's Functions, erstellt von Bee Brittain am 29/03/2016.
Bee Brittain
Mindmap von Bee Brittain, aktualisiert more than 1 year ago
Bee Brittain
Erstellt von Bee Brittain vor mehr als 8 Jahre
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Zusammenfassung der Ressource

2.4 Water and it's Functions
  1. The Dipolar water molecule
    1. A water molecule is made up of one Oxygen atom, and two hydrogen atoms
      1. oxygen has slightly negative charge, hydrogen has a slightly positive charge
        1. This means a water molecule has both negative and positive poles = dipolar
    2. Hydrogen Bonding
      1. Different poles attract
        1. Positive pole of one H2O Molecule is attracted to negative pole of another water molecule
          1. This is a hydrogen bond
          2. Although each H bond is fairly weak, together they form important forces that cause the water molecules to stick together
            1. These bonds give water its unusual properties
            2. Specific Heat Capacity of Water
              1. Hydrogen bonds between water molecules can absorb a lot of energy
                1. Water has a high specific heat capacity
                  1. this means it takes a lot of energy to heat it up
                    1. So water doesnt experience rapid temperature changes
                      1. This means it is a good habitat, as the temperature underwater would be more stable
                        1. It also means the water inside organisms is a fairly stable temperature - helping them to maintain a constant internal body temperature
                2. Latent Heat of Vaporisation of Water
                  1. Water has high latent heat of vaporisation
                    1. takes a lot of energy to break the H bonds between H2O molecules
                      1. a lot of energy is used up to evaporate water
                        1. Effective means of cooling when sweating as body heat is used to evaporate the water
                  2. Cohesion and Surface tension
                    1. Cohesion - the attraction between molecules of the same type
                      1. H2O molecules are very cohesive (tend to stick together) because they're polar
                      2. Strong cohesion helps water flow = great for transporting substances
                        1. E.g/ Its how water travels in columns up the xylem in plants
                        2. Strong cohesion = water has high surface tension when it comes into contact with air
                          1. This is the reason why sweat --> droplets
                            1. Reason why pond skaters and some other insects can 'walk' on the surface of a pond
                          2. Water is an important METABOLITE
                            1. Produced in condensation reactions
                              1. forming a new bond
                              2. Used in hydrolysis reactions
                                1. breaking a bond
                              3. Water as a solvent
                                1. dissolves gases e.g/ O2 and CO2
                                  1. dissolves wastes e.g NH3
                                    1. disolves inorganic ions and small hydrophilic molecules e.g/ Amino acids, monosaccharides and ATP
                                      1. dissolves enzymes, whose reactions take place in solution
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