 Xylem
 Structural spport and transport of wtare
 Cell wall have lignin nd celluslose
 Lignin is strong hard and water proof
 Bands wd different patters
XYLEM VESSELS
 Aka vessel elements
 Made of elongated cells joined en to end
 Non living
 Need hllow lumen and no organelles as
more speace for water and less
resistance
 Thick ccell wall made of celluslose allows
structureal support and allows adhesion
of water (is to celluslose)
 /cw/ contains lignin dats prevemts it
from collaposing and is water proof so
no water can leave and no end walls so
less resistance to water
 Pits form from plamodesmata nd have
no lignin. Allow lateral movement(side
way) of h20. It connects all parts of
plants. Air bubble dat blovk vessel pits
allow to move into another vessel to
bypass the watr bubble
PHLOEM
 Transport of assimilates (sucrose nd aa)
 Frm source ( site of synthesis of
photopsyntheitc products)
 To sink( site where asimalets stored)
 Through translocation
 Have sieve tube elements and
companion cells
 SIEVE TUBE ELEVMENTS
 Elengotaed seieee lements joind end to
end to form contionuos column called
sieve tie. SE are lving
 Have plasmodesmata allow loading of
sucrose to companion cells cc nd for
quik entery of water from near by
 Have tsrong vellulose to prevent
buldging due to excsess oressue from
sucrose moving in
 Has few organelles cellulose cell wall
plamas membrane nd itochondira n der
only
 No nucleus ribosome nd vacuoles
 Have peripheral cytoplasm lining cw
 This is so that there is less resitsnace to
flow nd max vol of phloem sap
containing assimaiates transpirte
 Have SEIVE PLATES (PERFORATED cw wd
many sieve pored)
 Cytoplasm of cells r connected
 Reduce barrier to flwo nd prevent
bugging nd pores become pugged wd
callose to prevent loss of ploem sap
after damage
 COMPANION CELL
 Next to sieve elemnts
 Many mitochondria as needs atp for
aerobic repirtaion for active transport of
translocation
 Many ribosome nd rer for polypepetide
produvtion
 Many plasmodesta for transport
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Xyem is just up the root
Phloem cn have upward nd downwards but each ploem will have either 1
TRANSPORT IN PLANTS
 Things transported is gases produvts of photosynthesis
mineral ions and h20
 Plants have a slower transport system than naimals as
lower enrgy fresuirement nd lower rate of respiration nd
lower requirement for oxygen and glucode
 Gsees transported thro simple diffusoi n nd leaves r thin
and flat and have a branch sha[e nd network fo air space,
high sa to vol ration
 Water nd ions move from root to xylem to atmosphere
 Produvys of [htosynthis froms srource to phloem to sink
 FOR H20 ND MINERAL IONS
 Both from root upwards
 Frm soil to root hair to cortex to endodermis to
xyem to mesophyll in leaves to stomata to
atmosphere
 MOVEMENT OF WATER FROM SOIL FROM
ROOT HAIRS
 Root cap is immerable to water and is tough to
provide protection
 Root haird r permeabke to water h20 nd
mineral ions r takeip by facilitated diffusion a
they have charge nd thro active transport
 Able to reach in soil partiles
 Delicate so replaced after few days
 Large SA more absorprtion
1. Soil ha a hugher water potential as root hair
cytoplasm hs higher conc of ion nd organic
substances eg protein dn sugar
2. Water diffuses down the gradienr via
osmosus thro partially permeable
memebrane
3. Itno vvacuole nd cytoplas of root hair
MOVEMNT OF H20 FROM HAIR TO CORTEX
 Hair have hgher than cortex nd so moves down
gradient thro osmosis
 3 routes
1. Apoplastic
 Thro cell wall or intercellular spaces
between cellusolos fibres
 Adhesion of water to celluslose nd water
does not corss membrares and neters the
cels
2. Sylplastic
 Thro cytoplasm
 Travel cel to cell via plasmodesmata
3. Vacular pathway
 Water cn pass into vasculoe, part of
symplashtic lil different
Aploplast has a cell wall has a
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MOVEMENT FROM ROOT HAIR TO CORTEX
TO EDODERMIS
Endodermis has asparuan strip(suvberized
strip)
Has waxy band of suberin in cell wall dats
impermeable
In endodermal cells apopolast blocked
Ony way to cross is thro cytoplasm in
sylmplast
Water nd iions pass thro endodermal cells
so transport of ions cn be controlled at
carrier protein of plasma membrane.
Asorbed by acve tran sort nd contribute to
root pressue
MOVEMENT OF WATRE FROM
ENDODERMIS TO XYLEM
Water cotnues down gradient
 Acorss pericycle(layer of cell lower
endodermis)
 pits in xylem vessles allow water inside
 root ha higher pressue den leave sso water
moves up from roots to leaves
FROM XYELM IN LEAVES TO ATMOPHERE
 xylem as highr poetential so down gradient
 xyelem vessels in leaves to pits of xylem
vessels to palisade nd spongy mesophyll to
surface of SM CW. Water on the surface of
SM evaporates into air space. Water from
air pace diffuses thro stomata into
atomospere. Air spaces r also saturates
after evaorationso hugher gradient
19 17 transporation vid 2
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Transpiration
Loss of water vapour from leaves
Causes cooling of leave
Thro stomata by diffusion only when its open for gas exhange and for entry for of co2
Loss from cuticle but very small amount
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Wat makes water move upwards
1. Transpirttional pull and cohesion nd adhesion of water
 During transpiration water vapor diffuse out of stomata the
evaportaion of water lower potential gradient
 At roots higher potential so water moves down gradient from
root to leaf thro xylem
 Transpiration from leaves creates transpirational pull
 ALONG WD DIS tension is set up in xylem due to H bonds
between h20 molecules nd cohesion bw h20 in xylem nd in root
cells nd adhesion of water molecules to cellulose cw of xylem
vessel
 Cohesion nd adhesion result in capillary action (ability of fluid to
move upwards against gravity in narrow spaces)
 THUS CREATING continuous colum of water extndinf from root
hair to stomata in leaves nd included qater from apoplasg thro
endodermis by osmosis
 Cohesion nd tesnsjon so strong dat it can cause trees to reduce
its girth when rate of transpiratntion is high
2. Root pressure
 Capsarian strip at endodermis bpock apoplast pathway so
water nd ions pass thro endoermal cell thro symphlast
 Solutes actively pumple across membrane jnto xylem
vessels in roots requiring atp
 Xv in root incrwases in solute conc
 Low water poetstiol
 Increase in hydrostatic pressure
 Water moves up root
Rate of transpirtajton
1.
2.
3.
4.
5.
6.
 Factors
Humidity low humidity steeper gradient
Wind speed hugher steeper
Mrke water inside plant steeper geadient as sotmata wld close is less water isnide
Temp rise ymo more ke nore evaporation byt cery high closes
Light high nore transliration due to increased ohotosythsis byt at very hugh close
Stonatal aoerature more wifth more water goes out
Rate on transpiration measured by potometer
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Rate 9f transpiration is rate of uptake however some used for respirstion nd hydrolysis
reactiom
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Plants living in places wd short h20 supple
Strcutral adaptations yo reduce h20 loss
Marram grass nd cactus
Adaptations
1. Rolled leafes exposing cutucle to routside air nd enclosing stomata
2. Haurs nd truchromes infolded inner surface dat trap water vapour
3. Sunken stomata minìmise affect of wind nd tràp layer of moist air
4. Reduce stomat
5. Leaves reduces to spines nd needles nd smalleaves so less sa bd protection
6. Thick water proof cuticle to increase distance
7. Multiplsyer epidermis to increase dustance
Xerophytes
How they gainor 3ater
1. Stems dat soak more water that r swollen.
2. Flattened and
3. deep extensive roots
TRASNPORT IN PLANYS
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TRANSLOCATION OF SUVROSE
1. Made at mesophyll
2. Loaded to companion cells
3. Translovated to seive tubes
4. Unloading of scurose in cells at sink
Transloactoion
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Transport of assilimalates
Assimilarted r soluble organic substances made by plant via photosynthesis like sucrose and aa
Transported as phloem sap in phloem tissue
SOURCES site of syntheis of photopyttic producets
laosing of OF scurose intk seive tubes here e.g mesophyll
SINk
Sitee where assimilated stored
Unloading from seive tube here e.g root hair tuber
Can be able or jelow soruve
Phloem sap cn mobe upward or downaeds but 1 way direction in 1 seive tube at 1 time
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MESOPHYLL CDLL TO NEAR SIEVE TUBES
Photosyntheis in mesophyll ro produce glucose covertes to suvrose
Transport of suvrose thro symphlast nd apoplast
LOADING OF SUCPRSE TO SEIVE TUBES
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Active transport involved as requires atp
H ioms in companion cells r pumped put into mesophyll cell wall
H ions gradient builds up
H ions re enter companiom cells down conc gradient using sucrose/h ions coytasporter protein
Sucrose cotransproted togetehr jnto companion cell again conc gradient
H ions via facilated diffusion
Suvrose transpoeted via secondary active transport
LOADING OF SUCROSE JNTO SEIVE TUBES
Survose diffuse from companion cell into seive tube down the conc geadient via plasmodemata
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TRASNOLCATION IN SEIVE TUBES
Presence of sucrose lower water potentiom in seive tube element
Water enters seive tubes via osmossi down the graideny
Increase hydrostatic pressure in seive tube near soruve
(water moving in flushes down the sucrose)
Near sink lower hydrostaric lrssure due to 7removal kf surcoese
So phloem sap wd sucroe move from region kf high to low lydrstatic lressure
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This results in mass flow which is moevemnt of fluids down a hydrostatic pressure gradient
Water in seive tube near sink has hugher hydostaic pressure than xylem vells due to amss flow
So qater moves back to xylem vessels down the hydrostatic pressure gradient
UNLAODJNF OF SUCROSE
Sink has lower conc
So moves down via diffusion
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At sink sucorse converted to glusocse fructose statch
Processed catalysed by enzymes
Used for respirations growrh and storage
TRANSOLCATION IS AN ACTIVE PROCESS