Transcript pink lily

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Think about it
10.1
How is water lost in transpiration?
10.2
How are water and minerals absorbed in the
roots?
10.3
How are water, minerals and organic nutrients
transported inside plants?
10.4
How are plants supported?
Practical 10.1
Practical 10.2
Practical 10.3
Practical 10.4
Practical 10.5
Practical 10.6
Practical 10.7
Practical 10.8
Summary concept diagram
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Sally has bought a bunch of coloured flowers.
Have you seen artificially coloured flowers
before?
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Sally has bought a bunch of coloured flowers.
How are flowers artificially made?
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Sally has bought a bunch of coloured flowers.
You can make coloured flowers by putting
white flowers, e.g. carnations (康乃馨),
into a solution of food colouring.
The solution is absorbed and transported
to the petals so that they turn to the colour
of the food colouring after several days.
How are flowers artificially made?
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10.1 How is water lost in transpiration?
All organisms lose water all the time.
 In plants: through transpiration (蒸騰作用)
H 2O
H 2O
H 2O
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10.1 How is water lost in transpiration?
The water lost must be quickly replaced.
 by absorption from soil in the roots
H 2O
H 2O
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10.1 How is water lost in transpiration?
Definition of transpiration:
The loss of water vapour from the surfaces
of plants due to evaporation.
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10.1 How is water lost in transpiration?
 > 90% of the total water loss from stomata
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10.1 How is water lost in transpiration?
 very small amount of water lost through cuticle
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10.1 How is water lost in transpiration?
 < 10% of water loss through lenticels (皮孔)
in woody stems
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10.1
Demonstration of the occurrence of transpiration
Procedure:
1 Set up the apparatus as shown in the diagram.
bell jars
intact
potted
plant
potted plant
with the aerial
parts removed
plastic bags
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10.1
Demonstration of the occurrence of transpiration
Procedure:
2 Leave both set-ups in bright light for 2 hours.
bell jars
intact
potted
plant
potted plant
with the aerial
parts removed
plastic bags
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10.1
Demonstration of the occurrence of transpiration
Procedure:
3 Observe any changes in the bell jars. Test any liquid formed
on the walls with dry cobalt (II) chloride paper.
bell jars
intact
potted
plant
potted plant
with the aerial
parts removed
plastic bags
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10.1 How is water lost in transpiration?
Transpiration
The process of
transpiration
A leaf section
1) Water on the surface
of the mesophyll
cells evaporates into
the air space.
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10.1 How is water lost in transpiration?
Transpiration
The process of
transpiration
A leaf section
2) Water vapour diffuses
through the stomata to
the outside down the
concentration gradient.
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10.1 How is water lost in transpiration?
Transpiration
The creation of
transpiration pull
1) Water is lost from the
permeable cell wall,
which is replaced by
water in the cell.
A leaf section
 Each cell then draws
water from its
neighbouring cells.
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10.1 How is water lost in transpiration?
Transpiration
The creation of
transpiration pull
2) Cells draw water from
the xylem vessels,
pulling water up the
plant.
A leaf section
 transpiration pull
(蒸騰牽引力) is
created
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10.1 How is water lost in transpiration?
Transpiration
Importance of transpiration
1) produces a cooling effect in the plant and
helps leaves withstand high temperatures
2) helps in the absorption of water and
minerals from the soil
3) causes the transport of water and minerals
in plants
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Distribution of stomata on leaves in terrestrial
and aquatic plants
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10.2
Design an investigation of the distribution of
stomata on both sides of a leaf
Bobby observed that the
dry cobalt (II) chloride
paper on the underside
of the leaf changed from
blue to pink faster than
the one on the upper
potted
plant
surface.
sellotape
on both
sides of
the leaf
dry cobalt (ll)
chloride paper
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10.2
Design an investigation of the distribution of
stomata on both sides of a leaf
He wondered if the
result was due to
different stomatal
densities of both sides
of the leaf.
sellotape
on both
sides of
the leaf
potted
plant
dry cobalt (ll)
chloride paper
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10.2
Design an investigation of the distribution of
stomata on both sides of a leaf
Design and perform an
experiment to compare
the distribution of
stomata on both sides of
a leaf.
sellotape
on both
sides of
the leaf
potted
plant
dry cobalt (ll)
chloride paper
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Distribution of stomata on leaves in terrestrial
and aquatic plants
Terrestrial dicotyledonous plants
• more stomata in the lower
epidermis than the upper
epidermis
• fewer stomata in the upper
epidermis: reduce water
loss
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Distribution of stomata on leaves in terrestrial
and aquatic plants
Submerged leaves of aquatic plants
• no cuticle
換 wb 金魚草相
• gases, water and minerals
diffuse directly all over
their surface
• few or no stomata in the
upper and lower epidermis
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Distribution of stomata on leaves in terrestrial
and aquatic plants
Floating leaves of aquatic plants
• have stomata in the upper
epidermis only
• no stomata in the lower
epidermis
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Distribution of stomata on leaves in terrestrial
and aquatic plants
Plant species
Number of stomata per cm2
Upper epidermis
Lower epidermis
0
1 200
14 100
13 000
0
0
9 500
0
Terrestrial dicotyledons
Apple
Tomato
Submerged leaves of
aquatic plants
Hydrilla
Floating leaves of
aquatic plants
Water lily
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Extension
Measuring the rate of transpiration
• with a potometer (蒸騰計)
a potometer
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Extension
10.3
Measurement of the rate of transpiration using a
bubble potometer
Procedure:
1 Cut a leafy shoot from a
plant and fit it tightly into
the bubble potometer
under water. Set up the
apparatus as shown. Seal
off all connections with
vaseline to ensure no
leakage of water.
leafy shoot
reservoir
beaker
tap (closed)
air bubble
water
graduated
capillary tube
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Extension
10.3
Measurement of the rate of transpiration using a
bubble potometer
Procedure:
2 Lift the end of the
capillary tube from the
beaker of water for 30 s
and then replace it to
introduce an air bubble
into the tube.
leafy shoot
reservoir
beaker
tap (closed)
air bubble
water
graduated
capillary tube
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Extension
10.3
Measurement of the rate of transpiration using a
bubble potometer
Procedure:
3 Wait for the bubble to
move into the horizontal
graduated part of the
capillary tube.
leafy shoot
reservoir
beaker
tap (closed)
air bubble
4 Record the distance
travelled by the bubble in
a certain period of time
(e.g. 5 minutes).
water
graduated
capillary tube
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Extension
10.4
Measurement of the amount of water absorbed
and lost by a plant using a weight potometer
oil layer
Procedure:
1 Cut a leafy shoot from a
plant and fit it tightly into
the weight potometer under
water.
burette
water
leafy
shoot
2 Set up the apparatus as
shown.
top pan
balance
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Extension
10.4
Measurement of the amount of water absorbed
and lost by a plant using a weight potometer
oil layer
Procedure:
3 Record the initial water level
(Vi) in the burette and the
weight (Wi) of the whole set-up.
4 After 24 hours, record the final
water level (Vf) and the weight
(Wf) of the whole set-up.
burette
water
leafy
shoot
top pan
balance
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Extension
Effects of the environmental factors on the
rate of transpiration
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Extension
10.5
Design an investigation of the effects of
environmental factors on the rate of transpiration
Donna put some roses in her
bedroom and some in the
sitting room.
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Extension
10.5
Design an investigation of the effects of
environmental factors on the rate of transpiration
Later, she found that the water
level in the vase placed in the
sitting room was much lower
than that in the bedroom. She
wondered if the environmental
conditions have affected
transpiration and water uptake
of the flowers.
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Extension
10.5
Design an investigation of the effects of
environmental factors on the rate of transpiration
Design and perform an
experiment to find out the
effects of an environmental
factor on the rate of
transpiration.
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Extension
Effects of the environmental factors on the
rate of transpiration
1 Light intensity
rate of transpiration
•
light intensity, the stomata
open wider
 more water vapour in the
air space can diffuse out

rate of transpiration
light intensity
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Extension
Effects of the environmental factors on the
rate of transpiration
2 Temperature
rate of transpiration
•
temperature
 (1)
rate of evaporation and
rate of diffusion of water
vapour out of stomata
 (2)
temperature

relative humidity
rate of transpiration
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Extension
Effects of the environmental factors on the
rate of transpiration
3 Relative humidity
rate of transpiration
•
relative humidity
relative humidity  the
concentration gradient of water
vapour between the air space
and the atmosphere
 less water vapour diffuse
out through stomata

rate of transpiration
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Extension
Effects of the environmental factors on the
rate of transpiration
4 Air movement
rate of transpiration
•
wind velocity
air movement  the
concentration gradient of
water vapour between the leaf
and the drier air outside
 rate of diffusion

rate of transpiration
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Brief Revision
1 The rate of transpiration can be measured
potometer
with an apparatus called _________.
2 Terrestrial dicotyledonous plants usually
have more / less stomata on the upper
epidermis than the lower epidermis.
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Brief Revision
3 An increase in light intensity will increase /
decrease the rate of transpiration.
4 An increase in relative humidity will
increase / decrease the rate of transpiration.
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10.2 How are water and minerals absorbed
in the roots?
Structure of the root
root cap
•
protects the tip of the root
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10.2 How are water and minerals absorbed
in the roots?
Structure of the root
epidermis
• made up of thin-walled cells
• protects the inner tissues from
diseases
• not covered by cuticle
• has many root hairs
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10.2 How are water and minerals absorbed
in the roots?
Structure of the root
root hair
• provides a large surface area
for water absorption
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10.2 How are water and minerals absorbed
in the roots?
Structure of the root
cortex
• consists of several layers of
thin-walled cells
• stores starch
• allows the passage of water
and minerals across the root
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10.2 How are water and minerals absorbed
in the roots?
Structure of the root
vascular bundle (維管束)
• transports materials into and
out of the root
• made up of xylem (木質部)
and phloem (韌皮部) tissues
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The adaptations of roots for absorption of
water and minerals
1) Epidermal cells are not covered
by cuticle and thus water can
easily pass into them.
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The adaptations of roots for absorption of
water and minerals
2) Numerous root branches
and root hairs provide a
large surface area for
absorption of water and
minerals.
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The adaptations of roots for absorption of
water and minerals
3) The root hairs are long, fine
structures.
 easily grow between
the soil particles
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10.6
Examination of the structure of roots
Procedure:
1 Examine the external structures of the root with a hand
lens. Draw a labelled diagram.
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10.6
Examination of the structure of roots
Procedure:
2 Examine the slide of the
transverse section of the root
with a microscope.
3 Identify the internal structures
of the root. Draw a labelled
diagram.
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Absorption of water in roots
1 Water moves into the
root hairs by osmosis.
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Absorption of water in roots
2a Water moves into the neighbouring
cortex cells by osmosis.
 it moves inwards
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from cell to cell Back
Absorption of water in roots
2b Some water moves
along the cell wall.
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Absorption of water in roots
xylem vessel
in the stem
3 Water is drawn
up the xylem
vessel by
transpiration
pull.
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Absorption of water in roots
4 Water evaporates from the leaf
cells and diffuses out through
the stomata as water vapour.
water vapour
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Absorption of minerals in the roots
Mineral salts dissolve
in soil water to form
ions (離子).
salts
ions
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Absorption of minerals in the roots
Ions are absorbed into
the roots by active
transport, using energy
from respiration.
salts
ions
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Absorption of minerals in the roots
Some minerals are also
absorbed in this way
by diffusion.
salts
ions
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Brief Revision
Root ____
cap serves to protect the tip of
1 ____
the root.
Vascular ______
bundle consisting of xylem and
2 _______
phloem, serves to transport materials in
and out of the root.
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Brief Revision
3 Root cells absorb water through osmosis
/ active transport / diffusion.
4 Minerals can be absorbed by plants
through osmosis / active transport /
diffusion.
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10.3 How are water, minerals and organic
nutrients transported inside plants?
Transport in flowering plants is provided by
the vascular tissues.
xylem
phloem
Patterns (分佈) in the roots, stems and
leaves are different.
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10.3 How are water, minerals and organic
nutrients transported inside plants?
LEAF
leaf vein
mid-rib vein
xylem
phloem
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10.3 How are water, minerals and organic
nutrients transported inside plants?
STEM
phloem
xylem
pith (髓)
epidermis
cortex
xylem
phloem
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10.3 How are water, minerals and organic
nutrients transported inside plants?
ROOT
phloem
xylem
cortex
epidermis
phloem
xylem
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10.7
Examination of the vascular tissues in a young
dicotyledonous stem
Procedure:
1 Examine the slide of the
transverse section of a
young dicotyledonous stem
with a microscope.
2 Identify the vascular tissues.
3 Draw a labelled diagram.
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10.3 How are water, minerals and organic
nutrients transported inside plants?
Xylem
• mainly consists of
xylem vessels
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10.3 How are water, minerals and organic
nutrients transported inside plants?
Xylem
3 characteristics:
1) Thick cell wall
• contains cellulose (纖維素) and
lignin (木質素)
• provides support to the plant
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10.3 How are water, minerals and organic
nutrients transported inside plants?
Xylem
3 characteristics:
2) Continuous hollow tube
• does not have cytoplasm
or nuclei
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10.3 How are water, minerals and organic
nutrients transported inside plants?
Xylem
3 characteristics:
3) No end wall between cells
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10.3 How are water, minerals and organic
nutrients transported inside plants?
Phloem
3 components:
1) sieve plate (篩板)
• the end wall between cells
• has holes for dissolved substances
to pass through
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10.3 How are water, minerals and organic
nutrients transported inside plants?
Phloem
3 components:
2) sieve tube (篩管)
• living cylindrical cells contain
cytoplasm but no nucleus
• cell wall is thin and does not
contain lignin
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10.3 How are water, minerals and organic
nutrients transported inside plants?
Phloem
3 components:
3) companion cell (伴細胞)
• found alongside each sieve tube
• contains cytoplasm and a nucleus
• supports metabolism of sieve tubes
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Transport of water and minerals
Water and minerals are transported in
xylem vessels.
 driven by transpiration pull
Transpiration pull is the suctional force
generated by transpiration.
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10.8
Investigation of the plant tissue responsible for
water transport
Procedure:
1 Immerse the roots of a
herbaceous plant in dilute
eosin solution for about
6 hours.
2 Cut transverse sections of the
root, stem and leaf. Examine
them with a microscope.
Identify the tissue(s) with red
colour.
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Transport of organic nutrients
Organic nutrients are transported in phloem
in 2 ways.
 up or down to the growing points for
development
 down to the roots or other storage organs
The process is called translocation (輸導作用)
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Summary for the transport of water,
minerals and organic nutrients in a plant
Transport of water
and minerals
1 Water and minerals are
absorbed into the roots.
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Summary for the transport of water,
minerals and organic nutrients in a plant
Transport of water
and minerals
2 Water and minerals
move up to other parts
of the plant.
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Summary for the transport of water,
minerals and organic nutrients in a plant
Transport of water
and minerals
3a Water and minerals
are used for
metabolism.
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Summary for the transport of water,
minerals and organic nutrients in a plant
Transport of water
and minerals
3b Water is lost in
transpiration.
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Summary for the transport of water,
minerals and organic nutrients in a plant
Transport of organic
nutrients
1
Organic nutrients
are made in
photosynthesis.
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Summary for the transport of water,
minerals and organic nutrients in a plant
Transport of organic
nutrients
2a Organic nutrients
move down to
growing fruit and
roots for storage.
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Summary for the transport of water,
minerals and organic nutrients in a plant
Transport of organic
nutrients
2b Organic nutrients
move up to the bud
for growth and
development.
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Brief Revision
1 Identify the following structures:
xylem
________
phloem
________
cortex
________
This is a transverse section of s_ t_e_m
_.
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Brief Revision
2
The process which organic nutrients
are transported throughout the plants is
translocation .
called ___________
3
Xylem is the main tissue which
______
transports water in the plant, while
phloem is responsible for the
_______
transport of organic nutrients.
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Extension
10.4
How are plants supported?
Plants are supported in two ways:
1) Turgidity of thin-walled cells
2) Hardness of thick-walled cells
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Extension
10.4
How are plants supported?
Turgidity of thin-walled cells
In a condition of adequate water supply:
• water moves in by osmosis
 the cells become turgid
plant stands upright
 press against each other
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Extension
10.4
How are plants supported?
Turgidity of thin-walled cells
In a condition of inadequate water supply:
• the cells will be plasmolysed
 become flaccid
plant wilts (凋謝)
 cannot press against each other
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Extension
10.4
How are plants supported?
Hardness of thick-walled cells
Xylem vessels
 contain lignin, which makes them hard
 provide mechanical support to the plants
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Extension
10.4
How are plants supported?
Hardness of thick-walled cells
As a woody plant (木質植物) grows, more and
more xylem is formed.
new xylem
cell
 the older xylem
tissues are
pushed inwards
and become
wood
mature
xylem cell
wood
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Summary concept diagram
absorption takes
place in
lose water
in
roots
absorb
water by
diffusion
Plants
absorb
minerals by
gain
support by
active transport
osmosis
E
transpiration
turgidity of
thin-walled cells
E
hardness of
thick-walled cells
in
in
E
E young woody
stems
E herbaceous
plants
woody plants
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Summary concept diagram
transpiration
creates
affected by
transpiration pull
E
light
intensity
E
temperature
E
relative
humidity
E
air movement
Back to summary
concept diagram
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Summary concept diagram
Plants
transport takes place in
vascular tissues
consist of
xylem
phloem
mainly consists of
transports
xylem vessels
transport
water
organic nutrients
minerals
Back to summary
concept diagram
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