The document discusses the transport system in flowering plants. It describes the two main transport tissues - xylem and phloem. Xylem transports water and dissolved minerals from the roots to the stems and leaves. It consists of dead cells with thickened lignified walls. Phloem transports sucrose and amino acids from leaves to other plant parts. It consists of sieve tubes with companion cells. The document outlines the processes of water and nutrient absorption by root hairs, and the movement of water up the stem via transpiration pull, root pressure, and capillary action. It also discusses the importance and factors affecting transpiration.

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Transport System in Plants
Prepared By: Faiz Abdullah

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Transport System in Flowering
plants
Flowering plants have a system of vessels that runs up and down
the plants carrying materials.
 These vessels are called transport or vascular tissues.
 YOU SHOULD KNOW TWO TYPES OF TRANSPORT
TISSUES:
① Xylem
② Phloem

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O Level question:
WHAT IS THE DIFFERENCE
BETWEEN XYLEM AND PHLOEM
TISSUES?

4. + XYLEM
1) FUNCTION
2) STRUCTURE
3) ADAPTATION

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XYLEM -- Function
salts
FROM roots to stems to leaves.
II. Provide for the stem.

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XYLEM –
STRUCTURE & ADAPTATION
 Consists mainly of xylem
vessels (long hollow tube)
 Made up of many DEAD
CELLS
 Inner walls of the xylem vessels
are STRENGTHENED by
LIGNIN  structural or
mechanical support
 Has empty lumen without
protoplasm or cross walls.
 Narrow lumen for capillary
action (not the same as
transpirational pull)
Structure ADAPTATION

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PHLOEM
FUNCTION:
Transports manufactured food
(sucrose+amino acid) from leaves
to other parts of plant.
STRUCTURE:
 Consists of sieve tubes and
companion cells.
Sieve tube consists of columns of
elongated, thin walled living cells
called sieve tube cells/elements.
They have cross walls with many
holes or pores  sieve plates
Each sieve tube has a companion
cell
ADAPTATIONS:
 Companion cells have many
mitochondria provide energy
needed to load sugars from
mesophyll cells into sieve tubes
by active transport.
 Sieve pores allow rapid flow of
manufactured food through sieve
tubes

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Phloem
Check out the:
1. Sieve tubes
2. Sieve pores
3. Companion cell
4. Sieve plates

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ROOT
The root is divided into several regions:
 The root cap: located at the tip of the root. root
during growth through the soil.
 Zone of cell multiplication/division: zone
 Zone of elongation: The region where newly divided cells
elongate of root.
 Zone of maturation: consists of root hairs, which increases
surface area for rapid and efficient uptake of water and salts

10. + Transverse section of the
root
Take note of the labels

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Vascular tissue in stem:
USEFUL TERMS
In dicotyledonous stem:
- Xylem and Phloem grouped together vascular bundle
- Vascular bundles are arranged in a ring around a central
region pith
- Phloem lies outside the xylem with a tissue in between
cambium
- Region between vascular bundles and the epidermis cortex
- Stem is covered by a layer of cells  epidermis

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Vascular tissues in a stem
• Cambium cells can divide and differentiate to form new
xylem and phloem tissues thickening the stem
• Cortex and pith serve to store up food substances such
as starch
• Epidermal cells are covered by a waxy, waterproof
cuticle that greatly reduces evaporation of water from
the stem

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ENTRY OF WATER INTO
PLANT
FROM ROOT  STEM 
LEAVES

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To understand the movement of
water:
We need to know how
WATER BEHAVES?

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PROPERTIES OF WATER
COHESION
Water molecules are attracted to
one another by a force 
cohesion
ADHESION
Water tends to stick to the inner
surface of the walls of xylem
vessels  adhesion

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Analogy

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1) Movement of water into
root hair cells

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1) Movement of water into root hairs:
Movement of substances
Water:
 OSMOSIS  water from the soil move into the root hairs via osmosis.
Mineral Ions:
 Diffusion: Ions diffuse from a high concentration to a low
concentration.
 Active transport: minerals, such as Mg and N, which are in LOWER
concentrations in SOIL, enter the root cell via active transport
OSMOSIS FOR WATER ONLY
FOLLOWS CONCENTRATION GRADIENT
NO NEED ENERGY
DIFFUSION FOLLOWS CONCENTRATION GRADIENT
ACTIVE TRANSPORT NEEDS ENERGY (ATP)
AGAINST CONCENTRATION GRADIENT

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1) Movement of water into root hairs:
Adaptations
a) Root hair is long and narrow  increase surface area to
absorb more water and mineral salts by root hair cell
b) Cell surface membrane prevents cell sap (vacuole) from
leaking out. Also, Cell sap has lower water potential.
c) Root hair is living  can provide energy for active transport

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1) Movement of water into root hairs
Once water has entered a root hair, it passes from one cell to
another by Osmosis.
This goes on and on and on……..and on….until the water
reaches the xylem
At the same time, ions diffuse inwards through the cells of the
root until they reach the xylem

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2) Movement of water UP the
stem

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2) Movement of water up the stem
1) Transpiration pull
Other forces involved:
2) Root pressure (Guttation)
3) Capillarity
4) Adhesion and cohesion of water molecules

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Transpiration

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2) Root pressure (Guttation)
 At night, mineral ions are actively transported into the xylem
vessel.
 This lowers the water potential in the xylem vessel.
 Therefore, water passes from the living cells into the xylem by
osmosis and flows upwards root pressure
 Guttation stops when transpiration begins

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3) Capillary action
When water reaches the xylem vessel,
Its NARROW LUMEN allows water to move up the stem  process known
as capillarity

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3) MOVEMENT OF WATER
THROUGH THE LEAVES

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3) Movement of water through the
leaves
 Mesophyll cells evaporate large quantities of water into the
intercellular air spaces
 Water vapor diffuses out of the leaves through the
STOMATA
 Small amount of water is lost through the waxy CUTICLE

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What is happening inside leaves..

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TRANSPIRATION
IMPORTANCE AND ITS FACTORS

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TRANSPIRATION IS
INEVITABLE/UNAVOIDABLE

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IMPORTANCE OF
TRANSPIRATION
 Enables water to move up the stem to the plants:
water can be used for photosynthesis and keep the cells turgid
(help leaves spread out widely to trap more light)
 Evaporation of water cools the plant.
 Enables plant to obtain mineral salts.
Why do you think transpiration
can help the plant?

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Transpiration- features that
facilitate water loss
(a) Mesophyll cells with wet surfaces and large total surface area
(b) Large intercellular spaces in the leaf
Other factors:
a) Greater number in stomata
b) Stomata exposed directly to sunlight or remain open

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Environmental factors that affect
transpiration
① Temperature
② Air Humidity
③ Wind
④ Light intensity
⑤ Carbon dioxide concentration
Guess!!!
Guess!!!
Guess!!!
Guess!!!
Guess!!!

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Pictures for transpiration factors

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WILTING 

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Wilting

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WHEN? And WHY?
Wilting occurs when:
RATE OF TRANSPIRATION EXCEEDS RATE OF ABSORBTION
OF WATER
 Cells lose their turgidity
 Cells become flaccid
 Plant wilts

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WHY wilting?
 Water becomes a limiting factor.
 Wilting causes a decrease in the rate of photosynthesis
Water is getting less
 Wilting makes the leaves fold less area exposed to sunlight
 The greater the size of stomatal opening, the greater the water
loss

39. + The transport or movement of
food substances in the
phloemTRANSLOCATION

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41. +
EXPERIMENT
Investigation: to show water travels up the stem in the xylem
Procedure:
1. Set up the apparatus as shown.
2. Allow the plant to stand immersed in the red food dye for 3-4
hours
3. Observe the color change in the stem
4. Cut thin transverse section of the stem
5. Observe under a microscope

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Observation
The red dye will appear in the stem and leaves.
Xylem tissue has been stained red