2.4 Water and it's Functions

Bee Brittain
Mind Map by Bee Brittain, updated more than 1 year ago
Bee Brittain
Created by Bee Brittain about 4 years ago


AS - Level Biology (2 - Nucleic Acids) Mind Map on 2.4 Water and it's Functions, created by Bee Brittain on 03/29/2016.

Resource summary

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