Explain how the physical properties of water enable organisms to survive over a range of temperatures.
Water has a very high specific heat capacity due to the collective forces of the many hydrogen bonds. A lot of energy goes into breaking these bonds rather than raising the temperature of the water, hence providing thermal stability which is important so the enzymes do not denature. Also due to its high specific heat capacity water can absorb a lot of heat energy before evaporating, known as the latent heat of evaporation, and so plays an important role in the cooling mechanisms to prevent organisms from overheating in high temperatures. Also, when water freezes the water molecules spread out more making ice less dense than water, hence the maximum density of water is at 40C and so ice floats on water. This insulates the water and the aquatic organisms underneath preventing them from freezing over. Also as the water underneath remains liquid it allows nutrients to still be able to circulate. The ice on top provides an additional habitat for the organisms in cold temperatures.
