The Transport System
Vascular plants transport systems consist of two main
systems which are the xylem and phloem.
Just like animals plants need food, sunlight, oxygen,
nitrogen, and other essential nutrients to survive.
These are obtain via the transport system in plants by
means of root pressure, cohesion-adhesion-tension
• Xylem transports the water and minerals from
the root hairs to the shoot system.
• It is made of many hollow dead cells joined
end to end of which the end cell wall has
disappeared to form a long tube.
• Xylem vessels contain no cytoplasm or nuclei
• Xylem tissue is made of cellulose and lignin
which in result assists to keep the plant
In vascular plants, phloem is the living tissue that carries
organic nutrients (known as photosynthate), in particular,
sucrose, a sugar, to all parts of the plant where needed. In
trees, the phloem is the innermost layer of the bark.
The phloem is concerned mainly with the transport of
soluble organic material made during photosynthesis. This
is called translocation.
Xylem and phloem tubes are normally found close
together, the arrangement of these tubes is called a
In the root system vascular tissue is found at the centre
In the shoot system they are found near the outside edge
to help support the plant
Transport of water
Plants take in water from the soil through the root hairs
and it is carried in the xylem throughout the plant
Water is absorb by root hairs by means of osmosis.
The cytoplasm and cell sap inside it are quite
concentrated solutions and the water in the soil is
normally slightly diluted
Water therefore diffuses down its concentration gradient
through a partially permeable membrane
Transport of Water…
Water is a polar molecule. When water molecules approach they form a
Hydrogen Bond. The negatively charged oxygen atom of one water molecule
forms a hydrogen bond with the positively charged hydrogen atom in another
Water enters the xylem in the roots by Osmosis. Once in the xylem the water
molecules hydrogen bond forming a continuous string of water molecules up
to the leaf.
Water is constantly lost by Transpiration in the leaf. When one water
molecule is lost another is pulled along. Transpiration pull is the main cause
of water movement.
What is Transpiration
The evaporation of water from the plant
Most of which takes place from the leaves through
Guard cells around the stomata control the rate
of transpiration by opening and closing
When water is lost through transpiration water from the xylem
vessel in the leaf will travel to the cells to replace it
Water is constantly being taken from the top of the xylem
vessel to supply the cells in the leaves
This reduces the pressure at the top of the xylem so water
This process is known as the transpiration stream, or
Evaporation of water at the surfaces of the mesophyll cells
followed by loss of water vapour from plant leaves, through the
Effects That Affect Transpiration
Transport of Food
TRANSLOCATION is the movement of sucrose and amino
acids in phloem, from regions of production to regions of
storage, or to regions of utilization in respiration or
Transport of Food…
The part of the plant from which sucrose and amino acids
are being translocated is called a SOURCE.
The part of the plant to which they being translocated is
called a SINK.
Leaves are generally the major sources of translocated
Sinks include the roots, flowers and fruits.
Transport of Food…
Sugar is made in the leaves by photosynthesis.
Sugar moves into the phloem tubes.
3a. The phloem tubes carry sugar to growing buds, which need
it for energy.
3b. The phloem tubes carry sugar to the roots, where it may be
used for energy or changed into starch and stored.
Transport the ‘food’ (sucrose and amino acids)
They are also made of many cells joined end to end, however
their end wall is not completely broken down; instead they
form sieve plates. The cells are called Sieve tube elements.
The cells contain cytoplasm but no nucleus and they do not
have lignin in their cell walls.
Each sieve cell has a companion cell next to it which does
contain a nucleus and many other organelles and supply sieve
tube elements with some of their requirements.
http://www.slideshare.net/PreetiGhosh1/transport-in-plants-31618755 date visited:
Date visited: 2014/03/05
Mindset Learn Channel
Date visited: 2014/03/05
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