1) The passage describes transport processes in plants, focusing on xylem and phloem. Xylem transports water and minerals upwards from the roots to the leaves, while phloem transports manufactured food such as sucrose downwards from the leaves. 2) Transpiration is the main process by which water moves from the roots to the leaves. Water evaporates from the leaves and this creates a transpiration pull that draws water up the xylem vessels. 3) The rate of transpiration is affected by temperature, humidity, wind, and light conditions. High temperatures, low humidity, high winds and strong light lead to higher transpiration rates.

1. Chapter 5:
Transport in Plants

2. Learning Objectives
Identify positions of xylem and
phloem in a dicot leaf, stem and
root
State the structures of xylem
and phloem & relate to their
functions

3. Transport of substances
How blood gets
transported in
our body?
How water, food
and minerals gets
transported in
Plants?

4. Imagine…
What transports water from the roots to the furthest
leaf?
Did You Know That?!
- Average of 60 meters in height
- A rainforest tree uses ~1200 L
of water/day
What do plants rely on?

5. The bottle tree plant,
‘Baobab’ that live 500 years and store up 300 litre of
water.
• BBC Video:
http://www.youtube.com/watch?v=M9V9bVEDSVs
• http://www.youtube.com/watch?v=U2iFl6lvj4c

6. Xylem
• Continuous long, hollow tube
• Dead, without protoplasm or
cross-walls
• Walls are deposited with
lignin, which is a hard and
rigid substance
Drawing
UndertheMicroscope
Describe what you see in the picture…

7. In flowering plants, the transport tissue consists of the
xylem and the phloem.
Xylem

8. Transports
&
Xylem
Function
Water Minerals

9. Lignin • Walls are strengthened with
lignin, which is a hard and
rigid substance
Xylem
Mechanical support

10. Phloem
Describe what you see in the picture…

11. • It is a living structure
• Made up of sieve tubes and
companion cells
• Transport food manufactured
in the leaves to other parts of
the plant by translocation
Phloem
(Sucrose)

12. • Food is either transported
or diffused through the
cytoplasm of the sieve tube
cells.
• Each sieve tube has a
companion cell beside it to:
 keep it alive
 provide energy for
active transport
Phloem

13. transportinplantstransportinplantstransportinplantstransportinplantstransportinplantstransportinplantstransportinplantstransportinplantstransportinplantstransportin
Function: Adaptations:
Transport
manufactured
food from the
leaves to other
parts of the
plants.
• Companion cells have
lots of mitochondria
which provides the
energy needed by the
sieve tube cells for
respiration.
• Holes in the sieve plates
allow transport of
manufactured food
substances through the
sieve tubes.
Phloem

14. Translocation (Phloem)
How do we know that the phloem transport
manufactured food??

15. translocationSTUDIES (pure)
Isotopes• The plant is grown in the
environment containing radioactive
carbon dioxide 14CO2.
• When photosynthesis takes place, the
sugar formed will contain radioactive
carbon.
• The cut stem section when exposed
onto an X-ray photographic film will
turn cloudy.
• This shows that the radioactive
substances are present in the phloem.

16. Aphids• Aphids are parasites that feed
on plants.
• Mouthparts (proboscis) of
aphids penetrate the leaf or stem
during feeding.
• When the body of the aphid is
cut off, leaving behind the
proboscis in the plant tissues, the
liquid will exude from the cut end
of the proboscis.
• The liquid is found to contain
sucrose and amino acids.
http://www.youtube.com/watch?v=J7eRGH
Vx3p0
translocationSTUDIES (pure)

17. Ringing experiment1. Removing a ring of bark
from a woody branch will
result in the removal of the
phloem tissue in that region.
Swelling will be observed in
the region above the ring.
2. The swelling above the
ring where the phloem is
removed will be caused by
an accumulation of sugars in
the region above the ring.
A
B
region with bark
removed
translocationSTUDIES (pure)

18. Translocation studies can be carried out using aphids. The
diagram below shows a section of a plant stem where the
proboscis of a feeding aphid may be found.
In which tissue would the proboscis most likely be inserted
into?
microQUESTION9.4
A
D
C
B

19. Vascular Bundle
• Xylem vessels + Phloem vessels  Vascular Bundle
• Found in the…
Root
Stem
Leaf

20. Magnification: 100X

21. Vascular Bundle of a Sunflower root

22. Vascular bundle
Root
Xylem
Phloem

23. Magnification: 100X

24. Phloem
Xylem
Vascular Bundle of a Sunflower Stem

25. Vascular bundle
Stem

26. vascularBUNDLE(pure)
XYLEM
PHLOEM
CAMBIUM
The xylem and the phloem group together to form a
vascular bundle (literally a bundle of vessels).

27. Magnification: 400X

28. Vascular bundle
Leaf
Xylem
Phloem

29. Transport in Plants
Xylem Phloem
Water
Mineral
Salt
Mechanical
Support
Lignified
Walls
Manufactured
food (Sucrose)
Sieve
tube
Companion
cell

30. Uptake of Water
30

31. Uptake of Water by the Roots
31

32. Movement of Water molecules
Osmosis is the net movement of water molecules
from a solution of higher water potential to a solution of
lower water potential through a selectively permeable
membrane
32

33. waterTRANSPORT
Root Hair Cell

34. Adaptation Function
Root hair cell has long
& narrow protrusions
Increase surface area to
volume ratio for faster rate of
absorption of water and mineral
salts
Cell surface
membrane prevents
leaking of cell sap
Maintain low water potential of
cell for osmosis
Living cell Provides energy from cellular
respiration for absorption of
mineral salts by active transport
Root Hair Cell Structure &
Function

35. Taking the train…
35

36. Please Consider the
following…
36

37. Uptake of water by Root Hair Cells
Xylem 37

38. How is water
transported from
the xylem in the
roots to the leaves?
38

39. In plants…
Plants only use about
5 to 10% of the
water they uptake
…for plant
growth and
cellular use
39

40. Eg. If a huge tree takes in
1200L of water a day and
only uses 10%...
Where did the other 90%
went to?
40

42. Water is loss to the environment mostly
through the?....
42

43. Let take a look at the cross section
of a leaf…
43

44. A large
percentage of
water that is
absorbed is lost
by evaporation
through the
stomata
44

45. This process of
water vapour
being lost
mainly through
the stomata is
known as
transpiration
45

46. How does
transpiration help
to bring water in
the roots to the
leaves?
46

47. Properties of water H
HO
Cohesive….’Attracts to one another’
Adhesive….’Attracts to other substances’
47

48. This creates a
suction force
which pulls
water up the
xylem vessels
This suction force due to
transpiration is known as
transpiration pull
48
In the stem, water moves
up the xylem primarily
via transpiration pull

50. Transport in Plants
50

51. 51
Purpose of Transpiration
Cools the leaves
Transport water &
minerals from the
roots to the leaves

52. Explain the factors affecting
the rate of transpiration
Learning Objectives
52

53. Factors Affecting Rate of Transpiration
• Temperature
• Humidity
• Wind
• Light
53

54. Which of the following correctly states the pathway in which
water molecules leave a plant during transpiration?
A ) Palisade mesophyll  vascular bundle  intercellular air
spaces  stomata
B ) Spongy mesophyll  intercellular air spaces  stomata 
epidermis  cuticle
C ) Vascular bundle  spongy mesophyll  intercellular air
spaces  stomata
D ) Vascular bundle  intercellular air spaces  stomata 
epidermis  cuticle ( )
microQUESTION9.8

55. Measuring Rate of
Transpiration

56. Experiment set-up to measure the rate of transpiration
(1) (2)
• In set-up (1), the loss of water by
evaporation is avoided by adding a layer
of oil on the surface of the water.
• Water is lost through the leaves of the
plant and will result in the mass of the
test tube decreasing.
Rate of transpiration = Loss in mass (g)
(g/h) Time taken (h)
• Set-up (2), known as “potometer”.
• The suction force generated by
transpiration will cause the air bubble in
the graduated capillary tube to move to
the left to indicate volume of water
absorbed to replace water loss.
Rate of transpiration = Loss in volume (cm3)
(cm3/h) Time taken (h)

57. 57

58. 58

59. 59
Distance
moved

60. Adaptation of ‘Marram grass’
• http://www.youtube.com/watch?v=Dv1-NDw49Vw

61. The transpiration rate of a plant varies throughout the day,
depending on the environmental conditions. Which of the
following sets of environmental conditions would result in the
highest transpiration rate?
microQUESTION9.9
Temperature Cloud cover Humidity Wind speed
A High Maximum High High
B Low Minimal Low Low
C High Minimal Low High
D Low Maximum High Low
( )

62. Wilting

63. Wilting
Excessive transpiration causes
a plant to wilt.
Wilting occurs when a plant
loses more water through the
leaves, than it absorbs through
the roots.

64. Wilting• Turgor pressure in the
mesophyll cells in the leaf
helps to support the leaf and
keep the leaf firm and widely
spread out to absorb sunlight
for photosynthesis.
• In strong sunlight, excess
transpiration causes cells to
lose turgor pressure and
become flaccid.

65. Wilting
Excessive Transpiration
Guard cells
become flaccid
* Rate of photosynthesis
decrease
Stomata close

66. Wilting- Advantage
• Less surface area exposed to sunlight
• Guard cells  flaccid  Stomata closes
• Transpiration is reduced

67. Wilting- Disadvantage
• Guard cells become flaccid  Stomata closes
• Carbon Dioxide intake is reduced
• Rate of Photosynthesis decreases