Summary CIE A-level Biology: Plant Hormones (A* achieved)

→ not
produced in specialised cells within
glands
→
different response in root I shoot

made in tissue
group of chemical substances
→ →



→
produced in
actively growing region eg .
stem →
one direction transport of auxin

→
diffusion 1 AT



•

phloem / xylem

→ Allows permanent cell
elongation to occur

→
effective on
younger cell walls before developing rigidity by secondary thickening


-




① stimulate elongation of Sterns
nnn




② Stimulate growth of lateral and
adventitious roots


↳ at 4) inhibits root growth

③ influences differentiation of an specialised
cells into
xylem /phloem




eg IAA=



Phototropism :


bending of plants towards tight ɱ
Auxins to w/ loner light
'




moves exposure
'




area
:

cells at this side elongate =

bending


auxin w/ no
light ,



q ÷q
avxins are

distributed evenly
elongation
,


growth 9




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