1.7 Water Flashcards
State 4 biologically important properties
of water
due to polarity and intermolecular H-bonds:
Metabolite / solvent for chemical reactions in
the body.
- high specific heat capacity.
- high latent heat of vapourisation.
- cohesion between molecules
Explain why water is significant to living
organisms
- Solvent for polar molecules during metabolic reactions
- Enables organisms to avoid fluctuations in
core temperature - Cohesion-tension of water molecules in
transpiration stream
Polar
Water is a polar molecule due to the uneven distribution of charge within the molecule - the hydrogen atoms are more positive than the oxygen atom causing one end of the molecule to be more positive than the other. As a result hydrogen bonding between many water molecules can occur allowing them to stick together
Metabolite
It is a metabolite in metabolic reactions such as condensation and hydrolysis which are used in forming and breaking of chemical bonds
Solvent
It is a solvent allowing gases to readily diffuse as well as enzymes and waste products, e.g. ammonia and urea
High specific heat capacity
It has a high specific heat capacity. This is because water molecules stick together with hydrogen bonds meaning that a lot of energy is require to break these bonds. This helps to minimise temperature fluctuations in living things therefore acting as a buffer
Large latent heat of vaporisation
Hydrogen bonding means that it requires a lot of energy to evaporate 1 gram of water. Therefore water has a relatively large latent heat of vaporisation, meaning evaporation of water provides a cooling effect with little water loss
Strong cohesion
Strong cohesion between molecules enables effective transport of water in tube like xylem. The strong cohesion supports columns of water, as a result of strong cohesion the surface tension at the water-air boundary is high
