biological molecules, importance of water

Question 1

the 10 different factors

Answer 1

solvent properties
transpiration steam
molecular mobility
expansion on freezing
metabolic functions
volatility/stability
transparency
supporting role
thermoregulation
lubricant properties

Question 2

solvent properties

Answer 2

allows water to act as transport medium for polar solutes
eg - movement of minerals to lankes and seas

Question 3

transpiration stream

Answer 3

continuous column of water is able to move up the xylem because of cohesion between water molecules and adhesion between water and walls of the xylem vessels

Question 4

molecular mobility

Answer 4

weak nature of individual hydrogen bonds mean that water molecules can move easily relative to one another
allows osmosis (vital for uptake and movement of water) to take place

Question 5

expansion on freezing

Answer 5

ice floats provide insulation for the water below it
this allows ice to thaw when temperature increases
the changes in density maintains circulation in large bodys of water
this helps nutrient cycling

Question 6

metabolic functions

Answer 6

water is used directly as
1. a reagent (source of reducing power) in photosynthesis
2. to hydrolyse macromolecules to their subunits, for example in digestion.
also medium in which all biochemicals take place

Question 7

volatility/stability

Answer 7

is balanced at earths temperature so the water cycle of evaporation, transpiration and precipitation are maintained

Question 8

transparency

Answer 8

water permits passage of visible light.
photosynthesis in relatively shallow aquatic enviroments

Question 9

supporting role

Answer 9

cohesive forces between water molecules means its not easily compressed - good medium for support

Question 10

thermoregulation

Answer 10

bodys mostly madde of water are very thermostable
they are less prone to heat damage by changes in enviromental temperature due to high specific heat capacity
high latent heat of vaporisation means body can be cooled with minimal loss of water
used for mammals and reptiles
important for cooling of transpiring leaves

Question 11

lubricant properties

Answer 11

cohesive and adhesive properties make viscous
examples
synovial fluid - lubricates many vetebrate joints
pleurae fluid - minimises friction between lungs and thorac cage during breathing