By Cheong Wing Lam
4A (08)

-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.

-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.

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

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.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.

-Water will be soon to ooze from the freshly cut stump of the plant.This is known as root pressure.

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.

Fig 13 Transpiration pull
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

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.

-The water level of the narrowest plant is the tallest.This phenomenon of water rising up a capillary tube is known as capillarity.

-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

-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

-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.

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.

-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.