Water Flashcards
Solvent properties?
allow water to act as a transport medium for polar solutes.
-movement of minerals to lakes and seas; transport via blood and lymph in multicellular animals;
removal of metabolic waste such as urea and ammonia in urine.
Transpiration stream?
the continuous column of water is able to move to the xylem because of cohesion between water molecules and adhesion between water and walls of the xylem vessels.
Molecular mobility?
the rather weak nature of individual hydrogen bonds mean that water molecules can move easily relative to one another, this allows osmosis(vital for up take movement of water)
What is a hydrogen bond?
Polarity means that individual water molecules can firm hydrogen binds with other water molecules.Although these individual hydrogen bonds are weak, collectively they make water a much more stable substances than would otherwise be the case.
High specific heat capacity?
specific heat capacity of water (amount of heat, measured in joules, required to raise 1kg of water through 1degree) is very high: much if the heat absorbed is used to break the hydrogen bonds which hold the water molecules together.
High latent heat if vapourisation?
Hydrogen bonds attract molecules of liquid water to one another and make it difficult for the molecules to escape as vapours:thus a relatively high energy input is necessary to vapourize water and water has a much higher boiling points than other molecules of the same size.
Molecular mobility?
weakness if individual hydrogen bonds mean that individual water molecules continually jostle one another when in the liquid phase.
Cohesion and surface tension?
hydrogen bonding causes water molecules to stick together, and also to stick to other molecules - the phenomenon of cohesion. At the surface of a liquid the inwardly acting cohesive forces produce a surface tension as the molecules are particularly attracted to one another.
metabolic function?
hydrolyse macromolecules to their subunits, in digestion.
as a reagent (source of reducing power )in photosynthesis.
Transparency
water permits the passage of visible light. This means that photosynthesis(and associated food chains)is possible in relatively shallow aquatics environments.
