1.7 and 1.8 Water and inorganic ions Flashcards
Where are inorganic ions found?
in the cytoplasm or in body fluids
What does inorganic mean?
doesnt contain carbon
What are the roles of H+ ion?
sucrose loading in the phloem and controlling the pH of body fluids
what are the roles of Ca2+ ion?
muscle contraction and synaptic transmission
What is the role of PO4 3- (phosphate) ion?
affects water potential
joins nucleotides and is in the backbone of DNA and RNA
used in ATP synthesis
lipid membranes - phospholipids
makes other molecules more reactive
What is the role of Na+ and K+ ions?
co-transport of gluclose/ amino acids into cells
sodium and potassium pump
sodium moved out by active transport
Creates a sodium concentration/diffusion gradient
Affects osmosis/water potential
What does a water having a high specific heat capacity mean?
takes more energy to heat a given mass of water
Why does water have a high specific heat capacity?
due to cohesion and hydrogen bonding
How does water make an aquatic environment stable?
acts as a buffer against sudden temp changes
What is the latent heat of vapourisation of water?
due to hydrogen bonds - requires a lot of energy to evapourate 1g of water
describe the structure of water.
dipolar - has two different charges, no overall charge
104.5’ bond angle
O is slightly - and has a higher affinity for electrons
H is slightly +
covalent bonds between H and O
What causes water molecules to stick together?
H bonds
Which is weaker H bonds or covalent bonds?
H bonds
What creates the surface tension of water?
downward facing H bonds
What is surface tension?
the water surface acts like a skin and is strong enough to support small organisms
What are all the properties of water?
universal solvent
high latent heat of evapouration
high specific heat capacity
metabolite
ice is less dense than water
cohesive
low viscosity
transparent
What is the biological importance of water being a universal solvent?
chemical reactions inside cells happen in aq solutions reactions are faster
water is the main transport medium in organisms
What is the biological importance of water having a high latent heat of evapouration?
acts as a coolant:
heat is lost from a surface when water evapourates from it which acts as a cooling mechanism eg: sweating
What is the biological importance of water having a high specific heat capacity?
acts as a buffer for changes in temp
cells can absorb/lose a lot of heat energy but only show a small temp change so organisms can live in extreme conditions
ensures that temp remains stable for cellular reactions
What is the biological importance of water being a metabolite?
water required in photosynthesis,in condensation reactions to synthesise biological polymers and in digestion of polymers via hydrolysis
What is the biological importance of ice being less dense than water?
thermal insulation = ice floats on water insulating organisms to live below it
What is the biological importance of water being cohesive?
acts as a transport medium:
long columns of water molecules dont break eg: water drawn up xylem, insects body supported on water’s surface
AND
produces surface tension so supporting small organisms on the water’s surface
What is the biological importance of water having a low viscosity?
water can flow easily therefore act as a lubricant eg: mucuis in the digestive system/ synovial fluid around joints
What is the biological importance of water being transparent?
light can pass through and aquatic plants can photosynthesise
allows fish to see as light hits the retina
What is the biological importance of water being polar?
It dissolves other polar substances
