Water

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  • Created by: Hindleyc
  • Created on: 18-12-17 21:11
How would you describe water molecules?
Charged
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Which part of the molecule is positive and which negative?
Hydrogen slightly positive and oxygen slightly negative
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What do these opposite charges do?
Attract each other forming hydrogen bonds
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What are the hydrogen bonds like?
Weak, long distance bonds - v common and important
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Why is water a solvent?
Charged so charged or polar molecules such as salts, sugars and amino acids dissolve readily in water (hydrophilic) and uncharged or non-polar molecules eg lipids do not dissolve (hydrophobic)
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What is the advantage of water having a high specific heat capacity?
Unusually high so water temp doesn't change easily minimises fluctuations in cells- sea temp constant- maintains temp for enzymes
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What is the advantage of water having a high latent heat of evapouration?
Water requires a lot of energy to change state from a liquid to a gas so can be used as a cooling mechanism in animals-sweating and panting maintaining body temp as extracting heat from around it, plants (transpiration)
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What is the relation of density with water?
Waters solid state is less dense than liquid state so floats on water so as air temp cools bodies of water freeze from the surface, forming a layer of ice with water underneath
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What is the advantage of a layer of ice and liquid underneath to animals?
Allows aquatic ecosystems to exist in sub-zero temperatures maintaining habitats
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What is water cohesion?
Water molecules stick together due to their H bonds
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What does water cohesion allow?
Columns of water to be sucked up tall trees by transpiration without breaking, surface tension allowing small animals to walk on water
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What is ionisation in water?
When many salts dissolve in water they ionise into discrete positive and negative ions
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What are many important biological molecules?
Weak acids that ionise in solutions
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Which form is found in living cells?
Ionised form
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What is water a source of?
Protons (H+) ions as water partially ionised
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What are many biochemical reactions sensitive to?
PH
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Why is pure water not a buffer and can easily be any PH?
Pure water cannot buffer changes in H+ concentrations
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What are the cytoplasms and tissue fluids of living organisms buffered at?
Neutral (PH 7-8)
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Why can water provide support to organisms?
Not easily compressed
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Why can Light rays through water?
Transparent
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Other cards in this set

Card 2

Front

Which part of the molecule is positive and which negative?

Back

Hydrogen slightly positive and oxygen slightly negative

Card 3

Front

What do these opposite charges do?

Back

Preview of the front of card 3

Card 4

Front

What are the hydrogen bonds like?

Back

Preview of the front of card 4

Card 5

Front

Why is water a solvent?

Back

Preview of the front of card 5
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