Water Flashcards
Role of Water in Biology?
found in living organisms = cytoplasm (all organisms), xylem/phloem (in plants), tissue fluid and blood (in animals)
also acts as habitats for living organisms
Properties of Water?
Water Molecules (H20) are dipolar
Hydrogen has slightly +ve charge and Oxygen has slightly -ve charge
therefore H20 molecules can form hydrogen bonds with each other
SHC
Water has high specific heat capacity meaning that a lot of heat needs to be applied before it evaporates due to the presence of the hydrogen bonds between the water molecules. Also when water freezes it becomes Ice, which is less dense then liquid water – so it floats on the surface insulating the water beneath it, preventing it from freezing. In both cases the water remains liquid to provide an habitat for organisms.
Solvent
Because H20 molecules are dipolar they can separate out solutes based on their charge, +ve Hydrogen side mixes with -ve solute and -ve Oxygen side mixes with +ve solute, so solute mixes with water and becomes dissolved. This is useful in cytoplasm of all cells and supports the reaction of these solutes, it is also useful in the processes of diffusion/active transport, and is also useful in transport such as blood and phloem.
Hydrostatic Pressure:
Water when pressurised can provide a strong physical pushing force. Used particularly in Mass Flow (where mass of water carries large amounts of substances e.g. tissue fluid in capillaries and phloem in plants). Also helps to support turgidity in plants.
SLH
Mammals and Humans control body temperature by sweating. Sweat on the skin uses heat from the blood to evaporate, hence, cooling the individual. Because sweat/water is made up of hydrogen bonds, it has a stable structure, so requires a large amount of heat for it to evaporate. This is called Latent Heat of Vaporisation.
What are Inorganic Ions?
Salts/Minerals
Inorganic = do not contain carbon, Ion = charged (+ve/-ve)
e.g. Sodium Ions (Na+), Chloride Ions (Cl-)
