Water Drop Journey in
Plants
Done By: Omar Ibrahim
Grade: 8B
General Idea
Have you ever heard of the term
“osmosis”? What about “water
concentration gradient”? We all know that
plants absorb water, and nutrients, from the
soil by the roots, and transport the water to
the leaves in order to carry the process of
making glucose, photosynthesis, which is
made by water, sunlight, carbon dioxide,
and chlorophyll, but did we ever know
how does a water drop move inside a plant
in exact details? Or even what happens to a
water drop when it falls from the sky,
enters the plant, and leave it again? This is
what I will explain in this presentation.
Precipitation
 To begin with, water falls from
the clouds by a process called
precipitation. What does
precipitation mean?
Precipitation is the water
released from clouds in the
form of rain, frozen rain, sleet,
hail, or snow. Precipitation is
the mean that starts the whole
water drop journey. After
falling from clouds, these water
drops land on Earth to become
part of the groundwater in the
soil, or little ponds or lakes
might be formed from the
falling water droplets.
Roots Absorption of Water
 As we know, the absorption of water
is carried out by the plant’s roots, but
what part exactly takes in the water?
Most of the water absorbed by the
roots is absorbed by an area in the
roots called piliferous region, also
called the root-hair layer and made of
hundreds of projections of the
epidermal tissue. The piliferous
region is the most area in the root in
which the water absorption happens
in, since this region has the largest
amount of root hairs in the whole
plant. Since the root hairs are narrow
walled, the surface area of the water
absorption increases. Water enters
the roots by a process called osmosis,
in which water is transferred from
where there is a higher water
potential to where there is a lower
water potential.
Inside the Roots and
Upwards

After entering the root hairs, water
moves to a vascular tissue, called
xylem, which transports water and
nutrients from the roots to the leaves, in
order to carry out the essential process
of photosynthesis. Where can we find
xylem inside the plant? The vascular
tissue, xylem, is found a central
column, surrounded by the
endodermis, the innermost layer of the
cortex that forms a sheath around the
vascular tissue of the roots and some
stems. The endodermis is covered by
the cortex parenchyma cells. The
parenchyma is the fundamental tissue
of plants, which is composed of thinwalled cells that has the ability to
divide.
Inside the Roots and
Upwards (Continuing)
 The water movement inside the plant
continues when the water
concentration gradient is established.
Water concentration gradient is the
graduated difference in concentration
of water per unit distance through a
solution, and since the roots have a
higher concentration of water
molecules than the leaves, water
moves from the roots to the leaves by
cell-by-cell transport. Water passes
from one cell to another either through
the cell wall, cytoplasm, or the vacuole.
This whole process inside the root
hairs and inside the xylem is called
Transpiration-Adhesion-TensionCohesion (TATC). Water moves from
the soil all the way up to the stems and
then to the leaves to carry
photosynthesis and get more food for
the plant, glucose, in order to survive.
Inside the Xylem
 The concentration of water
inside the xylem that
happens across the cortex
results in producing
something called the root
pressure, also known as
guttation, which is pressure
exerted in the roots of plants
which results from osmosis,
pushing the water outside
the plant, if part of the plant
was removed. Root pressure
is considered one of the
means that force water to
move upwards inside the
plant, instead of heading
downwards, and following
the gravitational force.
Structure of Xylem
 Xylem is known in the
plant to be narrow, long,
and hollow. Xylem also
consists of dead material,
and doesn’t consist of any
living material. Xylem is
impregnated, soaked,
with bands of lignin, an
organic substance that
acts as a binder for the
cellulose fibers in plants
and wood, and adds
strength to stop vessels
from collapsing.
Water in Leaves and Leaf
Structure

After water reaches the plant’s leaves, it
is now time for water to share in making
photosynthesis. This process requires
absorbing CO2, water, light energy, and
using chlorophyll, which is found in the
green organelle responsible for
photosynthesis called chloroplast. What
type of leaves can make absorption of
light more flowing? Broad leaves are the
best leaves for light absorption, since
they are thin, wide, and flat. This also
makes it easier for CO2 to enter the plant
through the stomata, small openings
that enable exchange of gas. Water, light
energy, and CO2 meet together in the
leaves, and make the process of
photosynthesis, converting light energy
to chemical energy, which is glucose.
Water in Leaves and Leaf
Structure (Continuing)
 After producing glucose from
the process of photosynthesis,
it is now time for the water to
be lost, transpiration or
evaporation, to return back to
the environment and form a
new cloud. Water can be lost
when also photosynthesis is
still happening, since the
stomata have two guard cells,
one to “open” the stomata, and
one to “close” it, and while the
carbon dioxide is taken in by
the stomata, water might
accidentally be lost. In most
broad-leaved plants, the
amount of stomata is found
higher at the back of the leaf,
enabling a fewer amount of
water to transpire, evaporate,
from the plant.
Out and Away!
 As transpiration takes place,
water diffusing into the air
spaces from the spongy
mesophyll cells takes its
place. After being lost, water
evaporates and reaches the
sky. After this step, all the
water droplets combine
together, becoming more
condense and making large,
thick clouds in the air, and
this process is called
condensation. Finally, the
water falls down again,
precipitation, as snow, rain,
frozen rain, sleet, or hail.
Water Drop Journey Video
 This is a very brief video that I found on the Internet
that explains the concept of the water droplet’s
journey inside a plant.
 The link to this video is:
http://www.youtube.com/watch?v=QYbg4lQ-iaU
Bibliography

http://www.microscopyuk.org.uk/mag/indexmag.html?http://www.microscopyuk.org.uk/mag/artmar00/watermvt.html

http://www.sparknotes.com/biology/plants/essentialprocesses/section1.html

http://static5.depositphotos.com/1032749/417/i/950/depositphotos_4171029Water-drop-on-leaves.jpg

http://2.bp.blogspot.com/MnmheO4MuOY/TyRcbN8EtYI/AAAAAAAAAxQ/mcR6kk5lvGQ/s1600/rain1.j
pg

http://ga.water.usgs.gov/edu/watercycleprecipitation.html

http://botanydictionary.org/piliferous-layer.html

http://www.microscopy-uk.org.uk/mag/imgmar00/roothair.jpg

http://faculty.uca.edu/johnc/RootHairsRadish.jpg
Bibliography
 http://www.thefreedictionary.com/endodermis
 http://content.answcdn.com/main/content/img/McGrawHi
ll/Encyclopedia/images/CE498100FG0010.gif
 http://www.thefreedictionary.com/concentration+gradient
 http://www.chaosscience.org.uk/sites/default/files/xylem_
5.jpg
 http://www.sbs.utexas.edu/mauseth/weblab/webchap9secr
etory/web9.3-1.jpg
 http://dictionary.reference.com/browse/parenchyma
Bibliography
 http://www.biology-online.org/dictionary/Lignin
 http://www.thefreedictionary.com/root+pressure
 http://lavonardo.net/wp/wordpress/wpcontent/uploads/2009/03/guttation.jpg
 http://www.extension.org/mediawiki/files/6/6d/Gutt
ation.jpg
 http://chenected.aiche.org/wpcontent/uploads/2010/11/lignin_h-1024x647.jpg
 http://micro.magnet.fsu.edu/cells/chloroplasts/images
/chloroplastsfigure1.jpg
Bibliography
 http://images.kish.in/2011/03/stomata2.jpg
 http://waynesword.palomar.edu/images/stomat2
b.jpg
 http://www.youtube.com/watch?v=QYbg4lQ-iaU
 http://www2.puc.edu/Faculty/Gilbert_Muth/pho
t0023.jpg
 http://www.historyforkids.org/scienceforkids/ph
ysics/weather/pictures/clouds.jpg
Thank you!