Water in Plants
By: Maisha Loveday 8C
S
Introduction
S Plants are living things that can create their own food by
photosynthesis using water, chlorophyll, carbon dioxide and
light energy from the sun. There are several key factors that
help the plant do this as well though. Water, chlorophyll,
sunlight and carbon dioxide are only the first part. The
distribution of the ingredients in the plant is another part of
the process.
Basic Water Movement in a
Plant
You can see that the water
starts at the roots, goes up
the stem through the xylem
tubes and then diffuse into
the air from the leaves.
The Roots & Tubes
S Water gets absorbed into the ground when it rains. The roots, which are
found in the bottom of the plant, are used to anchor the plant so it
doesn’t fall and to take in water and minerals for the plant. The root
hairs are the part of the roots that take in the most water through
osmosis, which is when the water in the soil has a weak solution of
salts, and the water passes form the soil into the root hair because the
cell sap in the root hair cell has a stronger solution. “osmosis is the flow
of water down a concentration gradient.”
http://en.allexperts.com/q/Molecular-Biology1353/2009/10/Osmosis.htm. Inside the roots there is a cortex, which
is used to store food as starch. In the roots and stem there are tubes or
veins called the xylem and phloem. These tubes are used to distribute
water and food around the plant. The xylem carries water and minerals
from the roots up to the leaves and the phloem carries food made in the
leaves all around the plant. So the water and mineral from the roots
travel up through the xylem to the leaves.
Xylem and Phloem Diagram
http://www.bbc.co.uk/schools/gcsebitesize/science/images/addgateway_plant_stem.gif
Stem
S The stem is basically the part of the plant that the leaves, flowers
and roots are connected to. The stem doesn’t actually take in
carbon dioxide, water, or sunlight but the xylem and phloem tubes
are in it so it used to help water, nutrients and food travel all
around the plant in both directions. Also, in environments where
there is little sunlight reaching the plant, the stem moves or leans
closer to the light so that the chlorophyll can get some light and
that is helpful because sunlight is a necessity in the process of
photosynthesis. After the water gets soaked in from the roots, it
travels in the xylem up the stem.
Leaves & Cells
S The leaves are the part of the plant that collects carbon dioxide through
tiny pores called stomata which close automatically when water from the
roots begin to dry up. Under a microscope, leaves have a layer of cells
called palisade cells. Inside the palisade cells there are small modules called
chloroplasts. Within the chloroplasts there is chlorophyll, which is a
chemical that gives, plants it’s green colour. Chloroplasts are used to
capture light energy from the sun. It is then stored in stacks of thylakoid
membranes, which is where photosynthesis takes place. Underneath the
layer of palisade cells there are spongy cells which are spaced out for
airspaces so there is room for gases like carbon dioxide and water vapour
to come in and out of the stomata under the spongy cells. The process in
which water evaporates from the leaves and into the air is called
transpiration. When the water in the leaves diffuses into the air, more water
is sucked up from the xylem tubes, this is called cohesion ‘sticking
together’. Adhesion is when water particles stick to other surfaces such as
the xylem. These things form a chain of molecules working their way up
the xylem due to adhesion and through the plant due to the cohesive chain
of water molecules.
Cells in Leaves Diagram
http://www.bbc.co.uk/schools/gcsebitesize/science/images/bi05004.gif
Basic Photosynthesis
Photosynthesis Equation:
Carbon Dioxide + Water  sunlight—chlorophyll  Glucose + Oxygen
http://www.youtube.com/watch?v=mpPwmvtDjWw
Plants in Doha
S Qatar is known to be a warm country. A lot of Qatar is
desert and even though there is hardly any water in the
desert, plants still grow and they adapt to the living
conditions of a desert. For example, cactuses are plants that
adapt to a desert environment and they do so by spreading
their roots so that there is more of a chance of getting water
and their wax cuticles tend to be thicker because that way
they can store more water and less water can diffuse from
the leaves and into the air. Plants can adapt to different
living conditions by doing things like this.
Bibliography
S
Ross, Adam. "Molecular Biology: Osmosis, Concentration Gradient, Plant Cells." AllExperts
Questions & Answers. 10 Nov. 2009. Web. 13 Feb. 2011. <http://en.allexperts.com/q/MolecularBiology-1353/2009/10/Osmosis.htm>.
S
GerstenfeldTeamS. "YouTube - Adhesion, Cohesion and the Ways Plants Acquire Water."
YouTube - Broadcast Yourself. 14 Oct. 2009. Web. 13 Feb. 2011.
<http://www.youtube.com/watch?v=kaMDrCgyrfo>.
S
Mediasematics. "YouTube - Photosynthesis." YouTube - Broadcast Yourself. 13 Dec. 2007. Web. 13
Feb. 2011. <http://www.youtube.com/watch?v=mpPwmvtDjWw>.
S
"BBC - GCSE Bitesize: Plant Transport." BBC - Homepage. Web. 13 Feb. 2011.
<http://www.bbc.co.uk/schools/gcsebitesize/science/add_gateway/greenworld/planttransportrev1.shtm
l>.
S
"BBC - GCSE Bitesize: Leaves and Photosynthesis." BBC - Homepage. Web. 13 Feb. 2011.
<http://www.bbc.co.uk/schools/gcsebitesize/science/add_gateway/greenworld/photosynthesisrev1.shtm
l>.
S
"BBC - GCSE Bitesize: Photosynthesis." BBC - Homepage. Web. 13 Feb. 2011.
<http://www.bbc.co.uk/schools/gcsebitesize/science/ocr_gateway/environment/1_food_factory1.shtml
>.