A1.1 Water

cohesion

water molecules stick to one another due to hydrogen bonds between molecules

water molecule

• a polar/charged molecule

• has regions of delta positive (H) and delta negative (O)

hydrophobic

non-polar molecules (e.g. fats, oils)

hydrophilic

polar molecules (e.g. sodium)

cohesion examples

• water being pulled up xylem in one continuous chain

• surface tension supporting organisms on surface of water

adhesion

water molecules stick to other polar/charged molecules

adhesion example

water molecules adhere to walls of xylem to resist gravity

high specific heat capacity

takes a lot of energy to change its temperature

high specific heat capacity example

water in seas and ponds stay at a constant temperature, stable for aquatic organisms to live in

high latent heat of vaporisation

tae a lot of energy to evaporate water

high latent heat of vaporisation example

as mammals sweat, liquid sweat evaporates takin heat energy away from the skin and providing a cooling effect

solvent

water dissolves any molecules that are also polar/charged

solvent example

blood plasma is water based so is able to transport dissolved substances to and from cells

Extraplanetary Origin of Water

when the Earth first formed it was over 100^oC so any water present would’ve evaporated meaning it came from somewhere else

Golidilock’s Zone

Earth is in the Goldilocks zone, its distance form the Sun is neither too far (cold) or too close (hot) to prevent liquid water

black-throated loon

• water cohesion (buoyancy) allows it to stay afloat

• overcomes water viscosity to dive and catch prey

• oily layer on feathers makes them waterproof to loose heat less quickly

• aquatic habitat is more thermally stable than the air (water has higher SHC)

ringed seal

• has thick layer of blubber to help insulate and lose less heat

• water cohesion provides buoyancy to help stay afloat

• streamline shape and paddle-like limbs help overcome water viscocity