OCR A-Level Biology Plant Transport(2) Summary

Stomata Close when :


furgor is low


Opening Guard cells pump in solutes by active transport sturgor increases
. :




Closing
:

Hormonal
signals from the roots
trigger turgor loss ->
water is conserved
Factors
Affecting transpiration light :

,
humidity , temperature ,
Air movement, Water availability

~sideplate
phloem A transports organic
S
living fissue which solutes
:




mpanion
CO e


⑧
sincture translocation
↳

sources Green leaves and stems
storage organs food stores
:


, ,




fruit or
Sinks Roots meristems
developing food stores i. e seeds
:
.
, ,




Phloem loading :



-Symplast Route Assimilates through cytoplasm and plasmodesmata passive
:


move the


-Apoplast Route :


7 Ations removed from
by active transport
are the
companion cen
.




H returns down
gradient via cotransport protein sucrose is co.transported into the
2 .


a a cen
.
3
Water moves into
high solute concentration companion cels building turgor pressure ,




4 and
Water assimilates are forced into the
phloem and move around the plant by mass flow
.




to areas of lower pressure the sinks

Phloem
Unloading Sucrose diffuses into sinks rapidly down a concentration gradient
:




Xerophytes
:
Plants adapted to live in areas of low water
availibility
↳ Adaptations :
·


Thick waxyfuticle Sunken Stomata
-

Fewer Stomata and leaves
-

Curled leaves

-Hairy leaves Parenchyma tissue to store water Leafloss
Long roots
-
- -




Hydrophytes Plants adapted to live in agreous environments
:




↳ Adaptations :



Thin or no
waxy Cuticle
-

Reduced Structure Wide flat leaves
,
-


Small roots

-large surface area Air sacs ->
floating
-



Arenchyma with air
space