Plant Nutrition and Transport

7/25/2019 Plant Nutrition and Transport

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PLANT NUTRITION

AND TRANSPORT


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The cellular and tissue structure of adicotyledenous leaf.


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Cuticle is a waxy layer which reduceswater loss through the upper epidermis.

Epidermis.The upper and lowersurfaces of leaf are covered by upper

and lower epidermis respectively.

Upper epidermis: Upper epidermis is aattened layer of cell that forms the

surface of the leaf and makes the cuticle.It consists of a single layer of closelytted cells without chloroplasts.The

stomata are usually absent.


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upper

epidermis

palisademesophyll

spongy

mesophyll

lower

epidermis

one stoma

cuticle

vein

xylem

phloem

LEAF ANATOMY


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Lower epidermis: It is provided withpore called stomata which are guarded

by kidney shaped guard cells. Theguard cells contain chloroplasts. Thestomatal pores open to facilitategaseous exchange. s a resulttranspiration also occur.

Palisade Layer:This is the mainphotosynthetic region of the leaf. The

cells contain numerous chloroplastsand are mainly photosynthetic infunction.


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DEMAL T!""#E "Y"TEM

epidermis

protection

single cell layer

cuticle waxy

no cells protection

stomata (opening) gas exchange

open & close to prevent H2O loss

surrounded byguard cells

prevents H2O loss


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Spo!y mesop"yll:contains spacesthat allows the movement of gases

and water through the leaf tissue.They have less chloroplasts.

#ascular $udle: contains the

transport system and vascular tissue!x"xylem# p"phloem$. $ %hloemtransports the products ofphotosynthesis !sugars# amino acids$.

&ylem transports water and mineralsinto the leaf tissue from the stem androots.


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'

Photosynthesis

Anabolic(small molecules combined) Endergonic(stores energy) Carbon dioxide (CO2)requiring process

that uses light energy (photons)andwater (H2O)to produce organicmacromolecules (glucose)

%CO& ' %(&O C%()&O% ' %O&glucose

(U)photons


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*ocusi! o t"e locatio o+ p"otosyt"esis i a plat


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*+

TranspirationTranspiration

The process of transpiration

1) ,ater on the surface of themesophyll cells evaporatesinto the air space.

A leaf section

The loss of water vapour from the surfaces

of plants due to evaporation.


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**

-ow is water lost in transpiration

ll organisms losewater all the time.

In plants: through transpiration

H2O

H2O

H2O


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*/

The water lost must be 0uickly replaced.

by absorption from soil in the roots

H2OH2O


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Transpiration stream

Water enters thelarge surface area of

the root hair cell. Water moves from the

root cell

Water moves through the stem in

the xylem( this is lignifiedso that

it is waterproof.)

Water arrives at the leaf and enters

the palisade cell for photosnthesis

As the leaf is warmed ! light some of the

water evaporates through the stomata if

the are open


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bsorption of water in roots

1 Water moves into the

root hairs ! osmosis.


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2a Water moves into the neigh!ouring

corte" cells! osmosis.

it moves inwards

from cell to cell


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2! #ome water moves

along the cell wall.


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$ Water is drawn

upthe "lemvessel !

transpiration

pull.

"lem vessel

in the stem


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% Water evaporatesfrom the leafcells and diffuses out through

the stomata as water vapour.

water vapour


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Transpiration is fast on a dr wind and hot

da as the water particles have a lot of

&inetic energ . The are more li&el to

evaporate and escapes through the open

stomata of the leaf.

Transpirationisslowe

ronahumid'cold

dathatisnotwinda

sthewater

particleshaveless&ineticener

g.The

arelessli&eltoevap

oratesand

escapethroughtheo

penstomata.


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Importance oftranspiration

1) produces a cooling e1ectin the plant and helpsleaves withstand high temperatures

2) helps in the absorption of water and mineralsfrom the soil

$) causes the transport of water and mineralsinplants


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/*

2 3+4 of the total water loss from

stomata


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//

,ater -apour diusest"rou!" t"e stomata tot"e outside.

A leaf section


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Thin outer wall

The guard cells control the openingand closing of the stomata

6uard cells accid

(toma closed (toma open

6uard cells turgid

Thick inner wall


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7istribution of stomata on leaves interrestrial and a0uatic plants

Terrestrial dicotledonous plants

more stomata in thelower epidermisthan

the upper epidermis

fewer stomata in the

upper epidermis:reduce water loss


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#u!merged leaves of auatic plants

no cuticle

gases# water andminerals di1usedirectly all over theirsurface

few or no stomatainthe upper and lowerepidermis


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loating leaves of auatic plants

have stomata in theupper epidermis only

no stomata in thelower epidermis


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*lant species+um!er of stomata per cm$

,pper epidermis -ower epidermis

Terrestrial dicotyledons

Apple

Tomato"u%merged leaves o&a'uatic plants

Hydrilla

Floating leaves o&a'uatic plants

Water lily

* /++

+

3 8++

+

*5 +++

+

+

*9 *++


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very small amount of water lost through cutic


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5+

/ E-irometal *actors Aecti! Traspiratio

). (umidity:" The lower the humidity outside the leaf the faster the rateof transpiration.

&. Air 0o-emet:" increase air movement increases the rate oftranspiration.

1. Temperature:" increase in temperature increases the rate oftranspiration.

/. Li!"t itesity:" greater light intensity increases the rate of

transpiration because it causes the stomata to open# so increasingevaporation through the stomata.


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5*

Itrisic *actors Aecti! t"e Rate o+ Traspiratio.

). Lea+ sur+ace area

&. T"ic2ess o+ epidermis ad cuticle

1. Stomatal +re3uecy

/. Stomatal si4e

5. Stomatal positio


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1ects of the environmental factorson the rate of transpiration

1Light intensity

rate

oftranspiration

light intensit

light intensity# the

stomata open widermore water vapour

in the air space candi1use out

rate of transpiration


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2Temperature

rate

oftranspiration

temperature

temperature

!/$ relative humidity


!*$ rate of evaporationand rate of di1usionof water vapour outof stomata



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3 Humidity

rate

oftranspiration

humidit

less water vapourdi1use outthroughstomata rate of transpiration

-umidity the

concentration gradient ofwater vapour betweenthe air space and theatmosphere.



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58

4Air movement

rate

oftranspiration

wind velocit

rate of di1usion


air movement

the concentrationgradient of water vapourbetween the leaf and thedrier air outside



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5;

-ave you seen articially coloured owers before

(ally has bought a bunch of coloured owers.


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Plant Nutrition and Transport

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