2. L E A R N IN G
O U TC O M E S
• To state the necessity for transport of
substances in plants
• To identify the vascular tissue in stem,
root & leaf
• To state the role of vascular tissue in the
transport of substances
• To describe the structure of vascular
tissue
• To relate the structure of xylem to
transport
3. plants
need
Water & mineral Food
Capillary
action Transported by
Root involves
involves
pressure xylem phloem translocation
Transpirational pull Relate to
structure
Results in Relate to
Transpiration
affecting Vascular
tissues
Factors
2. Air movement Found in
3. Temperature stem root
4. Light intensity leaf
5. Relative humidity
4. N E C E S S IT Y
• Essential to transport water & mineral
salts absorbed by the roots have to
be transported to all parts of the
plants.
• Water – as a solvent for biochemical
rxns, as reactants in cell metabolism
(ex.:light rxn)
5. • Mineral ions – for chlorophyll
synthesis, healthy plant growth &
development.
• Organic food materials synthesised by
the leaves during photosynthesis have
to be transported to the growing
regions, storage organs & other parts
of the plant.
• Small, simple multicellular plants no
need vascular system b’coz have a large
TSA/V ratio.
6. • Large flowe ring p lant @ angios p e rm s ,
conife r n fe rns h ave a s m all TS A/ ratio n
V
th e s u b s tance s h ave to m ove a gre ate r
d is tance ne e d vas cu lar s ys te m
• U nlike anim als , p lants are u nab le to p u m p
ne ce s s ary s u b s tance s th rou gh gre at
d is tance s , s om e tim e s re qu iring th e ne e d
to d e fy gravity.
• To ove rcom e , p lants u s e a com b ination of
root pres s ure, capillary action n
trans piration to p rovid e e nou gh force to
7. in
S tem, Root &
• X Y L E M Leaves & mineral
– transport water
salts
• P H L O E M – transport organic
substances
• Vascular system is not involved in the
transport of oxygen & carbon dioxide.
8.
9.
10. S T R U C T U R E O F X YL E M
IN R E L A T IO N T O
TR A N S P O R T
• It has two important functions :
– It transport water & mineral ions from roots to
the upper parts of the plant
– It also provide mechanical support to the plant
• In flowering plants, the xylem consists of
xylem vessels, tracheids, parenchyma & fibres.
• The vessels are elongated cells arranged
end to end. To allow water to flow in a
continuous column.
11.
12. • The end walls of the vessels have broken down
to provide an uninterrupted flow of water up the
plant.
• The side walls of xylem vessels are perforated
by pits, which allow water & mineral salts to pass
sideways.
• The lignified walls make the xylem vessels rigid
to prevent them from collapsing under the large
tension forces set up by the transpiration pull.
13. • The narrowness of the lumen of xylem vessels
increases the capillarity forces.
• The lignified walls of the xylem vessels increase
the adhesion of water molecules & helps the
water to rise by capillarity.
• Mature vessels are dead cells with no
protoplasm to obstruct the flow.
14.
15. • Conifers & ferns do not have xylem
vessels. They only have tracheids
which are less efficient in water
transport.
• Tracheids do not have open ends to
form a continuous hollow tube to
pass water from cell to cell through
pits.
16.
17. S TR U C TU R E O F
P H L O E M IN R E L A T IO N
TO TR A N S P O R T
• Transports organic food substances (sucrose
& amino acids) from leaves to various plant
parts
• Consists mainly of sieve tubes & companion
cells
• A sieve tube is a cylindrical tube made up of
elongated living sieve tube cells.
18. • The cross-walls separating the
sieve tube cells are perforated by
small pores. The cross-walls with
the pores look like a sieve & are
called sieve plates.
• There are cytoplasmic
connections between the sieve
tube cells through the sieve pores.
(allow the flow of dissolved food
materials from one sieve tube cell
to the next).
19. • M t e siev t ma cel or neles incl nucl degener t
aur e ubes ny l ga l uding eus ae.
• At l yerofcyt a &some mit
hin a opl sm ochondr ae found l t inside of
ia r ining he
t t celul cel w l l r a t t r pid fl ofnutient
he hin l ose l al ess esist nce o he a ow r
sol ion t ough t siev t cels.
ut hr he e ube l
• Compa cels ae onl found in fl er pl nt notin conifer orfer It
nion l r y ow ing a , s ns. s
a a &cl ya t w h t siev t cels.
dj cent osel ssociaed it he e ube l
20.
21. • Each companion cells has a nucleus,
dense cytoplasm & many
mitochondria.
• Help to transport manufactured food
from leaf cells into the sieve tubes.
• Many mitochondria to generate ATP
needed for active transport of sucrose
from companion cells into the sieve
22. • When a stem of a woody plant is ringed,
the bark containing tissues external to the
xylem (including phloem tissue) is
removed
• Nutrient solution containing organic
substances is prevented from being
transported to the roots.
• Food materials would accumulate in the
outer stem, above the ringed region of the
plant.
23. • In early stage, no wilting because
xylem vessels can still transport water
& minerals from the roots to the upper
parts of the plant.
• The plant eventually wilt & die
because food synthesised in the
leaves cannot be transported to the
root cells can no longer absorb
water & mineral salts from the soil
solution.
