Download Notes - Importance of Water

Water
Water

It is a main
component of all
organisms and
provides a medium
for metabolic
reactions to occur

Three properties
that make it
unique:
 Cohesive
 Solvent
 Thermal
Cohesion
Attraction between
molecules of the
same substance
 Water molecules
attract each other
because of H
bonds

Hydrogen bonding between water
molecules
Cohesion

Surface tension

Forms droplets
Adhesion
Attraction between
molecules of
different types
 Water sticks to
other materials


“Capillary action”
Expands When it Freezes

Ice is less dense than liquid water
Expands When it Freezes

Helps living things because:
 Ice
floats on lakes, ponds, etc.
 Colder water sinks “turnover”
 Arctic waters are insulated
 Water freezes inside the cracks of rocks
causing them to break apart (forms soil)
Water is a good solvent
“Universal solvent”
 Acts as a medium
for most
biochemistry in the
cell


Fluids in the body are
mostly H2O
 Cytoplasm, blood,
stroma
Solvent Properties

Water also acts as a
transport medium for
nutrients within organisms
 Xylem
and phloem in
plants
 Blood in animals carries
glucose, amino acids,
fibrinogen (clotting) etc.
Resist Temperature Change

Water has a high specific heat and
heat of vaporization
Water
requires a lot of heat to
increase its temperature
Cools slowly too
Resist Temperature Change
Acts as an insulator
for cells
 Keeps aquatic
environments
thermally stable
 Sweating/
transpiration allow
for rapid cool

Other properties

Colorless,
allows for a
lot of light to
pass through
tissue and
lakes, oceans,
etc.