Biological Molecules 6 - Water Flashcards
What happens when 2 water molecules are in close contact?
a weak hydrogen bond is formed as opposing charges attract each other
What do many H2O molecules form when there are many of them due to hydrogen bonding?
a strong lattice framework
What is cohesion?
when H2O molecules stick together due to hydrogen bonds
Why is cohesion useful in the xylem vessel of plants?
H2O molecules are attracted to each other and can be drawn up in a long unbroken column
What is adhesion?
the tendency of water to stick to hydrophilic molecules/polar molecules.
give the 7 properties of water and describe each of them.
surface tension - where water meets air, the water mol. form hydrogen bonds with other water mol. but not with mol. in the air. this cohesion produces an uneven distribution of force called surface tension causing the surface of water to form a skin, supporting aquatic plants and insects such as the pond skater
universal solvent - water is a solvent/polar molecule so it will attract and dissolve other charged particles such as ions and other polar molecules like glucose. it also acts as a great transport medium: in blood for animals and xylem vessels in plants
metabolite - reactant in photosynthesis and hydrolysis, produced during aerobic respiration and condensation reactions
high specific heat capacity - lots of energy needed to break hydrogen bonds and inc. temp. of water, providing a stable environment for aquatic organisms and enzymes can function effectively without becoming denatured
high latent heat capacity - lots of heat energy needed to break hydrogen bonds and change water from liquid to a vapour, lots needed to evaporate from surface of organism, providing a cooling effect as heat is removed from the body to evaporate water mol. like in sweating and transpiration
density - water less dense in solid state (ice) , therefore ice floats on surface of water, forming an insulating layer allowing aquatic organisms to survive in water underneath the ice and also providing a habitat
transparency - water allows light to pass through to underwater aquatic plants, enabling them to photosynthesise effectively.
