1.7 and 1.8 Water and inorganic ions

Question 1

Where are inorganic ions found?

Answer 1

in the cytoplasm or in body fluids

Question 2

What does inorganic mean?

Answer 2

doesnt contain carbon

Question 3

What are the roles of H+ ion?

Answer 3

sucrose loading in the phloem and controlling the pH of body fluids

Question 4

what are the roles of Ca2+ ion?

Answer 4

muscle contraction and synaptic transmission

Question 5

What is the role of PO4 3- (phosphate) ion?

Answer 5

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

Question 6

What is the role of Na+ and K+ ions?

Answer 6

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

Question 7

What does a water having a high specific heat capacity mean?

Answer 7

takes more energy to heat a given mass of water

Question 8

Why does water have a high specific heat capacity?

Answer 8

due to cohesion and hydrogen bonding

Question 9

How does water make an aquatic environment stable?

Answer 9

acts as a buffer against sudden temp changes

Question 10

What is the latent heat of vapourisation of water?

Answer 10

due to hydrogen bonds - requires a lot of energy to evapourate 1g of water

Question 11

describe the structure of water.

Answer 11

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

Question 12

What causes water molecules to stick together?

Answer 12

H bonds

Question 13

Which is weaker H bonds or covalent bonds?

Answer 13

H bonds

Question 14

What creates the surface tension of water?

Answer 14

downward facing H bonds

Question 15

What is surface tension?

Answer 15

the water surface acts like a skin and is strong enough to support small organisms

Question 16

What are all the properties of water?

Answer 16

universal solvent
high latent heat of evapouration
high specific heat capacity
metabolite
ice is less dense than water
cohesive
low viscosity
transparent

Question 17

What is the biological importance of water being a universal solvent?

Answer 17

chemical reactions inside cells happen in aq solutions reactions are faster
water is the main transport medium in organisms

Question 18

What is the biological importance of water having a high latent heat of evapouration?

Answer 18

acts as a coolant:
heat is lost from a surface when water evapourates from it which acts as a cooling mechanism eg: sweating

Question 19

What is the biological importance of water having a high specific heat capacity?

Answer 19

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

Question 20

What is the biological importance of water being a metabolite?

Answer 20

water required in photosynthesis,in condensation reactions to synthesise biological polymers and in digestion of polymers via hydrolysis

Question 21

What is the biological importance of ice being less dense than water?

Answer 21

thermal insulation = ice floats on water insulating organisms to live below it

Question 22

What is the biological importance of water being cohesive?

Answer 22

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

Question 23

What is the biological importance of water having a low viscosity?

Answer 23

water can flow easily therefore act as a lubricant eg: mucuis in the digestive system/ synovial fluid around joints

Question 24

What is the biological importance of water being transparent?

Answer 24

light can pass through and aquatic plants can photosynthesise
allows fish to see as light hits the retina

Question 25

What is the biological importance of water being polar?

Answer 25

It dissolves other polar substances