3.2 Water Flashcards
Importance of water for plants (2 things)
Photosynthesis
Keeps cells turgid
Why is water a polar molecule?
Oxygen holds a negative charge
Hydrogen holds a positive charge
So the water molecule contains both negative and positive charges
Importance of water for animals (5 things)
Water for blood plasma
Sweating
Chemical reactions
Habitat
Prevents cells from crenating
What are the weak bonds between water molecules called?
Hydrogen bonds
What are some unique properties of water?
High heat capacity
Cohesion
High latent heat of vaporisation
Low density solid
Solvent
Metabolite
Why is the cohesion of water important?
Hydrogen bonds hold water together so it can flow
Water boatman use water tension to float
Transpiration - allows water to be pulled against gravity (capillary action)
Why is it important that water has a high latent heat of vaporisation?
When molecule gains enough kinetic energy to break and evaporate, it takes energy with it
E.g. sweating
Why is important that water forms a low density solid?
Floats on top of water - creates habitat
Provides insulating layer for aquatic life
Why is it important that water acts as a solvent?
Positive and negative charges of water molecule attract other molecules causing them to separate from each other - dissolve
Metabolic reactions often happen only when dissolved in water
Transportation of materials in blood - dissolved minerals e.g. urea, glucose
Why is it important that water is a good metabolite?
Directly involved in chemical reactions
E.g. hydrolysis, condensation reactions and photosynthesis
What is meant by water having a good adhesion?
Water molecules are attracted to other materials
E.g. water doesn’t run straight off our skin
Why is it important that water has a high specific heat capacity?
Keeps temperature stable - acts as a coolant
Makes ocean a perfect habitat as temperature rarely changes throughout the year
Share of electrons between oxygen and hydrogen
Share electrons unequally as oxygen has a greater share so the more negative oxygen is attracted to the more positive hydrogen which forms a Hydrogen bond
Why is water an important component in blood?
Transportation
Site of chemical reactions
Cohesion - goes against gravity
Coolant
Polar molecule so allows other polar molecules to react with it
High specific heat capacity - temperature regularity
Why is water useful in the chloroplasts of the stoma?
Allows for movement of enzymes and substrates (water can be the substrate)
Allows chemical reactions to occur
