Presentation on transport systems in plants

1. UNIT 5:
SUPPORT AND
TRANSPORT
SYSTEMS IN
PLANTS

2. 1. ANATOMY OF
DICOTYLEDONOUS
PLANTS

3. ANATOMY OF
DICOTYLEDONOUS
PLANTS

4. Dermal, Vascular, and
Ground Tissues
• Each plant organ has:
DERMAL TISSUE:
OUTER PROTECTIVE
COVERING
VASCULAR TISSUE:
TRANSPORT AND
SUPPORT
GROUND TISSUE:
SPACE FILLERS

5. Dermal, Vascular, &
Ground Tissues

7. Dermal
tissue
Non-woody plants dermal tissue
system consists of epidermis
• waxy coating called cuticle helps prevent
water loss from epidermis
Woody plants protective tissues
called periderm replace epidermis
in older regions of stems & roots
• Trichomes outgrowths of shoot
epidermis & can help with insect defence.

8. Vascular
Tissues
Vascular tissue system carries out long-distance
transport of materials between roots & shoots
Two vascular tissues are xylem & phloem
Xylem conveys water & dissolved minerals
upward from roots into shoots
Phloem transports organic nutrients from
where they are made to where they are needed

9. Ground
Tissues
Tissues that are neither dermal nor
vascular are ground tissue system
Ground tissue internal to
the vascular tissue is pith;
ground tissue external to
the vascular tissue is
cortex
Ground tissue
includes cells
specialized for
storage,
photosynthesis,
& support

10. CROSS
SECTION
THROUGH A
DICOT ROOT

11. CROSS SECTION THROUGH A DICOT
STEM

12. CROSS
SECTION
THROUGH A
DICOT LEAF

14. 2. SECONDARY
GROWTH
Secondary growth occurs
in stems & roots of woody
plants  rarely in leaves
Secondary plant body
consists of tissues
produced by vascular
cambium & cork cambium

18. a. The
Vascular
Cambium
and
Secondary
Vascular
Tissue
The vascular cambium is cylinder
of meristematic cells 1 cell layer
thick
• develops from undifferentiated
parenchyma cells
Secondary xylem accumulates as
wood (consists of tracheids, vessel
elements & fibers.
• Early wood  formed in spring  has thin
cell walls to maximize water delivery.
• Late wood  formed in late summer  has
thick-walled cells & contributes more to
stem support.

19. Tree rings  visible where
late & early wood meet 
can be used to estimate a
tree’s age
Dendrochronology 
analysis of tree ring
growth patterns  can be
used to study past climate
change.
As a tree or woody shrub
ages  older layers of
secondary xylem
(heartwood)  no longer
transport water & minerals.
Outer layers (sapwood) 
still transport materials
through xylem.

20. a. The
Vascular
Cambium
and
Secondary
Vascular
Tissue

21. 3. UPTAKE OF
WATER AND
MINERALS
INTO THE
ROOTS
The plasma membrane directly controls the traffic
of molecules into and out of the cell.
In most plant tissues, the cell wall and cytosol are
continuous from cell to cell.
The cytoplasmic continuum is called the
symplast.
The cytoplasm of neighbouring cells is connected
by channels called plasmodesmata.
The apoplast is the continuum of cell walls and
extracellular spaces.

22. Water and
minerals can
travel
through a
plant by
three routes:
Transmembrane route: out of
one cell, across a cell wall, and
into another cell.
Symplastic route: via the
continuum of cytosol.
Apoplastic route: via the cell
walls and extracellular spaces.

23. Water and
minerals can
travel
through a
plant by
three routes:

24. Pathway 1:
Transmembrane
route
Water and
minerals move
from soil (high
WP) through cell
wall,
plasmamembra
ne & into
cytoplasm of
roothair.
01
Through cell
wall, plasma
membrane &
into cytoplasm
of cortex cells.
02
Through cell
wall, plasma
membrane &
into cytoplasm
of endodermis
03
Through cell wall,
plasma
membrane & into
cytoplasm of
pericycle.
04
Through cell wall,
plasma
membrane & into
xylem of plant.
05

25. CELLS
THROUGH
WHICH
WATER
MOVE
ROOTHAIR.
CORTEX CELLS.
ENDODERMIS
PERICYCLE.
XYLEM
Cell wall
Cell
membrane
Cytoplasm

26. Pathway 2:
symplastic
route
Water and minerals flow from high WP
in soil, through cell wall, plasma
membrane & into cytoplasm of
roothair.
Through plasmodesmata linking
cytoplasm of cells into cytoplasm of
the cortex cells.
Flowing through plasmodesmata into
cytoplasm of endodermis cells &
pericycle & into xylem.

27. Pathway 3:
Apoplastic
route
During Apoplastic route water &
minerals travel along cell walls of
roothairs, cortical cells, and
endodermis,
Endodermis has Casparian strips that
prevent further movement of water,
therefore water enter cytoplasm of
endodermal cells and then take:
symplastic route (through cytoplasm &
plasmodesmata that link cytoplasm of
cells) into xylem of root.

29. Transport of
minerals
across an
endodermal
plasma
membrane
Minerals follow same routes as water
when it moves through roothair & cortex
cells.
But when it moves through the
endodermal plasma membrane it does it
in the following way:
• An ATP driven pump removes hydrogen ions from
cell.
• This establishes an electrochemical gradient that
allows potassium ions & other positively charged
ions to cross the membrane via a channel protein.
• Negatively charged mineral ions can cross the
membrane by bonding to a carrier (hydrogen
ions) which are diffusing down their concentration
gradient.

30. CELLS
THROUGH
WHICH
WATER
MOVE
ROOTHAIR.
CORTEX CELLS.
ENDODERMIS
PERICYCLE.
XYLEM
ATP driven pump

31. Transport of
minerals across
an endodermal
plasma
membrane

32. 3. TRANSPORT OF WATER AND MINERALS
TO THE LEAVES
• What makes upward movement of water in
xylem of stems & leaves possible?
 Root pressure
 Cohesion-adhesion-tension
 Transpiration

33. I)
Root
pressure
• Water entering root cells creates
positive pressure called root
pressure.
• It occurs at night & push xylem sap
upwards.

34. II) Cohesion-
adhesion-
tension
model
Upward movement of water requiring no
energy.
Cohesion- Tendency of water molecules
cling together & form continuous water
column.
Adhesion- Tendency of water molecules to
cling to the sides of the container (xylem)
they are in. It gives water column extra
strength & prevents it from slipping back

35. III) Transpiration
Transpiration is loss of water vapour
through stomata of leaf.
Water molecules that evaporate from cells
into intercellular airspaces are replaced by
other water molecules from leaf xylem.
Because water molecules are cohesive,
transpiration exerts a pulling force /
tension, that draws water column through
xylem to replace water lost by stomata.
• This is also a mechanism by which minerals are
transported throughout plant body.

36. Environmental
factors that
influence the
speed of
transpiration
High temperature – faster
transpiration
High light intensity – faster
transpiration
Windy – faster transpiration
High humidity – slower
transpiration

37. What is
guttation and
what causes
it?
 Root pressure is responsible for
guttation.
 Guttation is when drops of water
are forced out of the vein
endings along the edges of leaves
called hydathodes.

38. 4. TRANSLOCATION
OF SUBSTANCES FROM
THE LEAVES TO THE REST
OF THE PLANT
Phloem sap is an aqueous solution
(high in sucrose)
travels from sugar source to
sugar sink
Products of photosynthesis are
transported through phloem by
process of translocation.

39. • Sugar source (organ producing sugar (mature leaves)
Sugar
• Sugar sink (organ that stores sugar (net consumer )
Sugar
• Sugar loaded into sieve-tube elements of phloem.
• Sugar moves by symplastic or both (symplastic and apoplastic) pathways.
Sugar
• At the sink, sugar molecules diffuse from phloem to sink tissues & are
followed by water.
Sugar

40. TRANSLOCATION
OF SUBSTANCES
FROM THE LEAVES
TO THE REST OF
THE PLANT