- this an important process for a
process of 'sucking up' of minerals
and water by the xylem is called transpiration. It
is just like
sucking up a straw.
and dissolved minerals are transported, through the Xylem, from the root to the leaves.
The transpiration ('sucking up') is caused
by the evaporation of water inside the leaves to the surrounding
The water vapour passes out of stomata by diffusion.
leads to a lack of water in the spongy
mesophyll cells of the leaves.
The lost water is then replaced by more water from the xylem which in turn
draws up more from the roots.
benefits the plants in two ways:
Replaces lost minerals from the soil.
It has cooling effect on the plant -
just like animals sweating.
affecting the speed of transpiration.
Amount of light - more light will increase transpiration as rate of photosynthesis
Temperature - increased temperature increases both evaporation and photosynthesis,
thus increasing transpiration.
Extent of air
movement - increased air movement increases evaporation, thus
Humidity of the surrounding air - decreased humidity increases evaporation, thus
The condition of stomata - Turgid stomata allows more water to escape by diffusion, hence
the above information, it is quite apparent that the highest rate of transpiration
occurs during sunny, hot, dry and windy conditions.
conditions for putting your washing out!
Remember: The TURGIDITY (fluid
the cells help a plant to stay upright and keep leaves firm.
When plants have ample supply
of water, all their cells 'suck up' water
into themselves by osmosis and turn turgid.
The 'watery' content of
vacuoles in the cells start to press against the cell wall, just like tire
tube against the tire, and so gives support to the plant tissue.
pressure also help the leaves to stay
'stiff'. You have probably seen this
with potted plant, if you don't water it for some weeks, the plant starts
to 'wilt' and the leaves 'droop'.
This is due to the fact that cells start to lose
water and thereby lose their turgor