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Water Transport in a Plant
By: Ghaida Odah 8C
Introduction
We all know that plants need water to
grow and live. What we might not know is
how that water that is first put in the soil
moves up the plant and all the way to the
leaves. In this presentation you will learn
all about how water in transported in
plants and the importance of movement of
the water in plants.
Step 1
The major path for water movement into
plants is from soil to roots. Water enters near
the tip of a growing root, the same region
where root hairs grow. The surface of the root
hairs need to be in close contact with the soil
to access soil water. Water diffuses into the
root, where it can take at least three different
pathways to eventually reach the xylem, the
conduit located at the interior of the root that
carries the soil water to the leaves.
Apoplastic Path
One of the 3 paths that the water can
travel through in order to reach the xylem
is the aoplastic path. In the apoplastic
path, water travels through the apoplast
which is the cell wall region. It travels
between the cells never crossing the
membranes.
Transmembrane Path
In the transmembrane path, water travels
straight through the cells of the cortex to
the endodermis by entering a cell on one
side and exiting on the other side, In this
path, water crosses at least two
membranes for each cell in its path.
Symplastic Path
In the symplastic path, water travels
through the symplast which is the part of
the cell bound by a membrane. It uses
plasmodesmatal connections between the
cells.
Step 2
Once at the endodermis, each water molecule is
forced to move across cell membranes in order to
enter th endodermal cells because the lipophilic
Casparian strip surrounding the endodermal cells
is a barrier.
While the water following the transmembrane and
symplastic paths travel past the Casparian strip
easily, the water that takes the apoplastic path
cannot move around cells anymore and therefore
must enter the cell by crossing its membrane
because of the strip.
Step 3
After the water molecules bypass the
Casparian Strip, they enter the Stele and
travel into the xylem.
The water enters the xylem through pits in
the xylems vessels or tracheids. Then,
water joins the upward flow of water
through the vessel elements and tracheids
to reach the stems and leaves of the plant.
Transpiration
Once the water reaches the leave sin a
plant transpiration occurs. Transpiration is
the evaporation of water from plants. It
occurs chiefly at the leaves while their
stomata are open for the passage of CO2
and O2 during photosynthesis.
Thank You!