Plants have developed two pathways for transporting water and nutrients throughout their systems: 1) The apoplast pathway transports substances through the cell walls and extracellular spaces between cells. 2) The symplast pathway allows direct transport between cell cytoplasm through plasmodesmata. The main driving forces for transport in plants are root pressure, which pushes water up short distances, and transpiration pull, where water loss through leaves creates suction to draw water up from the roots. Transpiration is driven by temperature, light exposure, humidity, and other environmental factors. Together these pathways and driving forces work to transport water, minerals, and food throughout the plant body to sustain growth and survival.

1. TRANSPORTATION
IN PLANTS

2. • How water reaches the top of all tall
trees ?
• How and why substances move from
one cell to the other ?
• Do plants have circulatory substances
?
So how do the live ?
Only by photosynthesis… ?

3. Introduction…
• Plants need to move molecules over long
distances, much more than animals do.
• The photosynthates or food synthesized by the
leaves have also to be moved to all parts
including the root tips embedded deep inside
the soil.
• Short distances travel of substances i.e.,
through membranes.

4. Transportation ?
• So it is the process ie, Transportation –
Transport of substances from one part to
another part within plant body.
• Over small distances ie, between adjacent cells
it takes place by diffusion.
• Over long distances it is through vascular
system (xylem and phloem) and is called
translocation.

5. Continued…
• In rooted plants, transport in xylem is
unidirectional, from roots to stems.
• Organic compound synthesized in leaves and
are exported to other parts of the plant
including storage organs.
• The mineral nutrients are transported upwards
• If any plant part goes under senescence,
nutrients will be withdrawn from that part and
moved to growing parts.

6. Means of Transport

7. Diffusion
Factors affecting diffusion:
• Concentration gradient,
• Permeability of membrane; separating the
substances
• Temperature and Pressure

8. Facilitated Diffusion
• While non-polar substances diffuse through the
membrane, the polar substances move with
help of special proteins. This process is called
facilitated diffusion.
• Special proteins help the substances move
against concentration gradient and this is
energy dependent process.
• The energy for this is supplied by ATP.
• Facilitated diffusion happens with the help of
proteins which are selective in nature.
• Such a transport is also sensitive to inhibitors.

9. Continued…
• Carrier proteins form porin channels in the
outer membranes of plastids, mitochondria and
some bacteria. The porin channels allow the
molecules up to the size of small proteins to
pass through molecule bound to the transport
protein. The transport protein then rotates and
releases the molecule inside the cell. For
example; water channels are made up of eight
different types of aquaporins.

10. Symports, Antiports & Uniport

11. Active Transport
• Active Transport: Energy pumps are used
against a concentration gradient; in case of
active transport. Active transport is carried out
by membrane proteins. Pumps are proteins
which use energy to carry substances across
the cell membrane. The rate of transport
reaches the maximum when all the protein
transporters are being used or are saturated.

12. Comparison of Different
Transport Processes

13. Plant-Water Relations

14. Water Potential

15. Solute Potential
• Solute Potential: All solutions have a lower
water potential because of the dissolved
solutes. The magnitude of lowering of water
potential is called solute potential (Ψs). It is
important to remember that solute potential is
always negative.
• For a solution at atmospheric pressure:
Water potential = Solute potential

16. Pressure Potential
• Pressure Potential: If a pressure; greater
than atmospheric pressure is applied to
pure water or a solution, its water
potential increases. This happens
because of pressure potential which
develops due to increased pressure.
Pressure potential is usually positive.
Pressure potential is expressed as Ψp.
• Ψw = Ψs + Ψp

17. Osmosis

18. Plasmolysis

19. Classification of Plasmolysis
• Plasmolysis classified on the basis of
osmotic pressure and concentration
gradient
o Hypertonic Solution
o Hypotonic Solution
o Isotonic Solution

20. Hypertonic Solution
• Cytorrhysis ?
It is complete collapse of the cell wall due to
further plasmolysis in the cell.

21. Hypotonic Solution

22. Isotonic Solution

23. Imbibition
• Imbibition: When water is absorbed by
solids (colloids), resulting in an enormous
increase in volume, this is called
Imbibition. Seeds swell up because of this
process.

24. How do Plants absorb Water ?
• Absorption of water from the soil happens
through root hairs. Root hairs are extensions of
the root epidermis and have thin walls. Water
enters Long the distance root hairs because transport of osmosis.
of
Presence Water
of numerous root hairs increases the
surface area and hence enhances the
absorption of water.
• The further movement of water takes place by
two distinct pathways-
• Apoplast pathway
• Symplast pathway.

25. Apoplast Pathway
• Apoplast Pathway: The free diffusional space
outside the plasma membrane is the apoplast.
This is interrupted by the Casparian strip in
roots, air spaces between plant cells and the
cuticula of the plant. The apoplast is formed by
the continuum of cell walls of adjacent cells as
well as the extracellular spaces. The apoplast
pathway facilitates the transport of water and
solutes across a tissue or organ.

26. Symplast Pathway
• Symplast Pathway: The inner side of the plasma
membrane is the symplast. The symplast
pathway is made continuous because of the
presence of plasmodesmata across the cell
walls of adjacent cells. Small molecules; such
as sugars, amino acids and ions; flow through
symplast pathway. Larger molecules are also
transported through this route with the help of
actin structures.
• The symplast pathway allows direct cytoplasm
to cytoplasm flow of water and other nutrients
along concentration gradient.

27. Water movement up a Plant

28. Root Pressure
• Root Pressure: When various ions from the soil
are actively transported into the vascular
tissues of the roots, water also follows.
• This increases the pressure inside the xylem.
This positive pressure is called root pressure.
• The root pressure can push water up to small
heights in the stem.

29. Guttation
• Guttation: In some plants, under the conditions
of low evaporation, water comes out from the
tips of leaves.
• Such loss of water in its liquid phase is called
guttation.
• Guttation takes place in smaller plants only.

30. Limitations of Root Pressure
• Limitations of Root Pressure: Root pressure
can only provide a modest push.
• Hence root pressure does not play a major role
in water movement in tall plants.
• Root pressure contributes towards
reestablishment of continuous chains of water
molecules in the xylem; which often break
under enormous tensions created by
transpiration pull.

31. Transpiration Pull
• Transpiration Pull: The evaporative loss of
water by plants is called transpiration.
• Transpiration mainly occurs through stomata.
• Stomata are usually open during daytime and
remain close during the night.

32. Factors affecting
Transpiration Pull
Factors Affecting Transpiration:
• Temperature,
• light,
• humidity,
• wind speed,
• number and distribution of stomata,
• number of stomatal aperture with guard
cells open,
• water status of the plant,
• canopy structure, etc.

33. • Question – 1- What are the factors affecting the rate of diffusion?
• -Factors affecting diffusion are; Concentration gradient, Permeability of membrane;
separating the substance, Temperature and Pressure.
• Question – 2 - What are porins? What role do they play in diffusion?
• - Carrier proteins form porin channels in the outer membranes of plastids,
mitochondria and some bacteria. The porin channels allow the molecules up to the
size of small proteins to pass through molecule bound to the transport protein and
thus allow facilitated diffusion.
• Question – 3 - Explain why pure water has the maximum water potential.
• -Water molecules possess kinetic energy. A system with higher concentration of
water has a higher kinetic energy or water potential (Ψw). Hence, pure water has the
highest water potential.
• Question – 4 - What happens when a pressure greater than the atmospheric
pressure is applied to pure water or a solution?
• - If a pressure; greater than atmospheric pressure is applied to pure water or a
solution, its water potential increases. This happens because of pressure potential
which develops due to increased pressure.
• Question – 5 - Explain what will happen to a plant cell if it is kept in a solution having
higher water potential.
Questionnaire

34. THANK YOU
MADE BY-KUSHAL R PANDEY
CLASS -XI-A (SCIENCE)
SCHOOL -COAST GUARD PUBLIC
SCHOOL,DAMAN