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Biology Project
Transport in plant
By Cheong Wing Lam
4A
(08)
1.0 Transport In Flowing
Plants
-Transport is provided by vascular tissues.
-All flowering plants contains vascular tissues.
-The tissues consist of special cells and tubes,no pump is present.The
upward transportation is completed by osmosis.
-The vascular tissues form bundles consist of xylem and phloem cells.
The bundles run through the root, stem and leaves continuously.
- They are distributed in the root, stem and leaves in different patterns as
shows in Fig 4.
Fig 4
Distribution
of vascular
tissues in
plant leaves,
stems and
roots.
1.1 Transport of water
1.11 Xylem
-Its main functions is transport water.
-They consists of long tubular vessels.
-Xylem vessels is made up of many dead cells which are hollow and
joined end to end.
-They contain no cytoplasm or nuclei.
-They transport water from the root through the stem to the leaves.
-Its another functions is supporting the plant.
-They have thick cell walls made of cellulose and they are strengthened
by rings of a woody substance called lignin in order to prevent collapse.
Experiment1.11
To show the route of water transport in a plant
1.Obtain a herbaceous plant and clean its roots with water.Do not
damage the roots.
2.Immerse the roots in a container of a dilute eosin solution for about 6
hours.
3.Cut transverse sections of the root,stem and leaf.Examine each
section.Identify the tissue which carries the red color.
Fig 6 Dye experiment
Conclusion
In the root, stem and leaf sections, the xylem tissues are found to contain
the red color. Thus, the xylem must be the tissue for transport of water.
Xylem vessels are responsible for the of water up the plant. In flowering
transport plants, water forms a continuous stream inside xylem vessels
from the root to all of the branches in the stem and leaves.
The main method which transports water up the xylem vessels is the
transpiration pull. Loss of water from the leaves will draw water out of
the xylem vessels there. As the column of water in the xylem vessel from
the root to all branches of leaves is continuous, this loss of water from
the upper end of the vessel in turn pulls water up the vessel. Water in the
xylem vessels is therefore moved up as the plants transpire.
As water is moving up the plant, the minerals and other substances
dissolved inside are also transported with the water. They can then be
absorbed by surrounding cells.
1.12 Root pressure
Experiment 1.12
To show that water are collected by root
pressure
1.Prepare a plant (with soil) and cut a stem near its base.
2.Use a rubber tubing to connect with a glass tube as shows in Fig 11.
3.Examine the water rise from the glass tubing.
Fig 11
Root pressure
Conclusion
-Water will be soon to ooze from the freshly cut stump of the plant.This
is known as root pressure.
1.13 Transpiration pull
Experiment 1.13
To show that water can be transported by
transpiration pull
1.Mixed some water and mercury in a beaker.
2.Connecting a plant (without root) to a water-filled tube and put the tube
in the bottom of the beaker as show in Fig 13.
3.Examine the rises mercury level.
Conclusion
During transpiration, water is continually
removed from the top of xylem vessels to
supply cells in the leaves.This reduces the
pressure at the top of the xylem vessels,so
that water flows up in them.This force is
called transpiration pull
Fig 13 Transpiration pull
1.14 Capillarity
Experiment 1.14
To show that different diameter in stem will
have different capillarity
1.Prepare four plants A, B, C and D in different diameter in stem (cut the
stem as same as Exp.1.12)
2.Connect each stem with glass tubes as same as Exp.1.12.
3.Examine the rising water level in the four plant.
Conclusion
-The water level of the narrowest plant is the tallest.This phenomenon of
water rising up a capillary tube is known as capillarity.
1.2 Transport of nutrients
1.21 Phloem
-The main function is transporting nutrients.
-Phloem is made of tube cells called sieve tubes.
-Sieve tubes are living cells and cylindrical in shape.
-Sieve tubes are joined end-to-end,contain cytoplasm but no nucleus.
-The end walls between sieve tubes have many holes, like a sieve and are
therefore called sieve plates.
-The holes allow dissolved substances to flow from one cell to
another,materials also can be transported through the sieve tubes.
-Sieve tubes do not have lignin in their cell walls.
-Each sieve tube has a companion cell next to it.
-The companion cell contains cytoplasm and nucleus.
-Companion cells support the activities of the sieve tubes, supply sieve
tubes with their metabolic need.
Fig 16 Phloem cells
1.22 Transport of organic
nutrients
Translocation
-Organic nutrients are produced by leaves. The organic nutrients are
transported to other parts of the plant by the phloem cells. This process is
called translocation.
Fig 20
translocation
2.0 Non-flowering plants
-Mosses,ferns and gymnosperms contains vascular tissues (xylem and
phloem) .Therefore, they have the similar transport system as flowering
plants.
-Algae have no vascular tissues and transport water and nutrients directly
by osmosis, the cell walls and cell membrane act as the selectively
permeable membrane.
-Fungi are not classified to the plant kingdom.
Summary
1.Flowing plants
-Plants have two separate conducting tissues.Xylem carries water and
mineral salts from the roots to the leaves.Phloem carries foods from the
leaves to all other parts of the plant.Xylem and phloem are often found
together in the plant as vascular bundles.
-Xylem consists of vessels which are made up of dead,hollow cells
joined end to end and without cross walls.
-phloem is made of sieve tubes and companion cells. Sieve tubes are
living cells joined end to end by perforated walls called sieve plates.
-three forces are responsible for the upward transport of water and
mineral salts in plants:toot pressure, capillarity and transpiration pull.
2.Non-flowering plant
-Mosses,ferns and gymnosperms contains vascular tissues.Therefore,
they have the similar transport system as flowering plants.
-Algae have no vascular tissues and transport water and nutrients by
osmosis.
THE END