Water is a polar molecule. It can appear positive or negative (dipolar)
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Dipolar
Negative charge ion at one end and positive charge ion at the other
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How is water dipolar?
Oxygen has a slight negative charge and hydrogen has a slight positive charge
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Hydrogen bonds
Positive and negative ends of the molecules (water) are attracted to each other
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Cohesion
Sticking together of water molecules
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How is cohesion important to living organisms?
Water molecules cohere together up the xylem vessels at low pressure. This means water forms continuous columns up to the top of a tree for photosynthesis
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Adhesion
Forming hydrogen bonds with other molecules
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How is adhesion useful to living organisms?
It is useful in leaves as cellulose molecules in cell walls. Water evaporates into the leaf air space and adhesive forces cause water to be drawn out of xylem vessels. Ensures cells walls are moist for gas exchange
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Latent heat of vaporisation
Energy required to change a substance from liquid to a gas
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What is water's latent heat vaporisation?
Water has a high heat latent of vaporisation because of hydrogen bonds
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How is water a good coolant?
Inside our bodies energy is used to evaporate water to create sweat
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How is water a high specific heat capacity?
It requires a lot of energy to raise the temperature. Conversely, a lot of energy must be lost before the temperature falls.
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How is high specific heat capacity useful to living organisms?
Aquatic environments do not under go large fluctuations in temperature as water maintains a constant temperature so fish survive
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What particles dissolve in water?
Charged particles can dissolve in water
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How is water useful in blood plasma?
Blood plasma is mostly water and so substances can be dissolved and transported around
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What substances are dissolved and transported in blood plasma?
Sodium chloride; amino acids; glucose
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How is oxygen transported around the body?
Oxygen is non-polar but it is small so some is dissolved. The saturation level is too low to allo for Arabic respiration so oxygen has to be carried by haemoglibin
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What substances don't dissolve in water?
Lipids they are carried in the blood as liprotein complexes (layer of phospholipidsin contact with the water)
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Other cards in this set
Card 2
Front
Dipolar
Back
Negative charge ion at one end and positive charge ion at the other
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