Form 5 Biology SPM

1. The Transport of
Substances in Plants

2. 2Bio Form 5 Chapter 1 Transport by AHM
Transport
organic substances
from leaves to
storage organs (roots,
buds)
Transport
water and mineral
salts absorbed in the
roots, up the stem to
the leaves

3. 3Bio Form 5 Chapter 1 Transport by AHM
-Xylem vessels
-Tracheids
-Parenchyma
-Fibres ( a type of sclerenchyma)
-sieve tube
-Companion cell
-Parenchyma
-fibres

4. Translocation
• The transport of dissolved organic solutes
(sugar sucrose, amino acids, metabolites)
in the phloem
• Important for plant’s survival & enables
organic substances eg sucrose to be
stored or converted to other sugar
• Translocated downward from leaves to
storage organs ( roots, growing region
and buds)
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5. Translocation – from SOURCE
(leaf cell to SINK (root cell)
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6. Transpiration
• Loss of water vapour from a living plant
due to evaporation
• Take place through stomata & lenticels
• Importance of transpiration :
– helps in the absorption & transport of water
and mineral ions from the roots to other
parts of the shoots
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7. Transpiration
• Transpiration stream = the continuous
stream of flowing water from the roots to
the leaves
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8. The Process of Transpiration
Roots  xylem vessels  leaves (mesophyll cells)
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-Surface of mesophyll
cells are covered by a
thin layer of water
-Air space is saturated
with water vapour as
the Sun heat the
external surface
-[H20 vapour] in
atmosp. Is lower than
water vapour in air
space  water
evaporates from leaves
-The loss of water make
the mesophyll
hypertonic as compared
to an adjacent cell
-Water from adjacent
cell diffuse
-Create transpirational
pull

9. The External Conditions that
affects the rate of transpiration
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Light intesity
Temperature
Relative
Humidity
Air movement

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11. The Movement of Water from soil  leaves
• Movement of water through the roots
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•Water enter from soil to roots
cells through osmosis
[cytoplasm of root hair cells are
hypertonic compared to the
surrounding soil water]
• the cell hypertonic compared
to adjacent cells
• water diffuse into adjancent
cells
•Water move inwards to cortex
•Cortex = cytoplasm, vacuole,
cell wall of parenchyma cells
=until endodermis

12. - Via cell wall is blocked by Casparian
strip at endodermis (impermeable to
water)
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13. • Root pressure = results in the
upward push of water &
mineral ions into the xylem
of the stem
• The gradient of water
concentration that exists
across the cortex creates a
pushing force that results the
inflow of water into the
xylem
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14. • Small plants = the root
pressure can push water all
the way up to stem and
hydathodes @ edges of
leaves  GUTTATION
• Occurs on cool humid
mornings
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15. The Movement of Water from soil  leaves
• Movement of water through the stem
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-Adhesive and cohesive
properties of water molecules
-Xylem are long, narrow &
hollow column of water and
creates capillarity / capillary
action
-Water molecule adhere to one
another = cohesive force
-Water molecule adhere to the
xylem vessels = adhesive forces
-Due to hydrogen bonding

16. The Movement of Water from soil  leaves
• Movement of water from LEAVES to ATMOSPHERE
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-Transpirational pull =
force due to the water cohesive
properties that draw water from
the xylem of the leaves and
stems and eventually from the
xylem in the roots
Root pressure, the adhesive
and cohesive properties of
water (capillary action) and the
transpirational pull contribute to
the movement of water from
roots to the leaves

17. The Regulation of transpiration by the stomata
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18. The Regulation of transpiration by the stomata
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