How are Big Trees able to get
water to the top??
Transpiration
• Plants continually
lose water to the
air.
• This is called
transpiration.
Transpiration
Stages in transpiration
1) Water is constantly lost
from the leaves- this occurs
due to evaporation due to
heat + water loss from the
stomata
Transpiration
Stages in transpiration
2) This produces a
concentration gradient:
There is more water in the
roots/ at the base of the
plant that in the leaves.
Water moves via osmosis
from a high concentration in
the roots to a lower one in
the leaves.
Transpiration
Stages in transpiration
3) As water moves from the
roots to the leaves more
water is drawn up from the
soil into the root hair cells.
This occurs because the
concentration of water in the
soil is larger than in the
roots = water moves via
osmosis in to the root hair
cells.
• The guard cells
control the size of
the stomata, so can
regulate the amount
of water lost by
transpiration.
• If plants are losing
water faster than
they are gaining it,
the stomata close.
• Without this
happening, the
plants will wilt – and
may die.