Summary
OCR Biology A-Level Plant Responses Summary
A HandWritten summary which contains all the necessary A* Content for Plant Responses at OCR A-Level Biology.
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Plant Limitations not mobile and:
They are lack a nervous
system
Guava n
Tannins toxic bad
.. or
tasting
:
·Alhaloids Bitter :
toxic bad smeu organiz
, ,
Compounds
Pheromones Signalling molecules
↳ Some
:
that influence other
organisms' behaviour
also fold to touch
plants
Auxins (IAA) Stimulate the growth of the
apical shoot and increases the
elasticity of
:
the sell wall
by promoting the active
transport of Ht into the sel wall
↳ Auxin is produced in the apical meristem and diffuses down the stem
↳once and vacuole and
the cell wall streches encymes destroy the auxin no further
dongation can occur
High auxin concentration inhibits later
growth sapical dominance
As auxin concentration decreases down the lateral dominance
plant occurs
low auxin concentration root
encourages growth
Abscisic Acid acid apical dominance
High auxin a
high abscisic s
:
Cytokinins High auxin :
Cytokinins are in the shoot apex sapical dominance
:
Gibberellins Affects the internodes
length of
:
the
↳ Activates which are needed seed
genes for germination
·
experimental evidence :
seeds without Gibberelling
Mutant wont
geminate
Seeds won't
with gibberelling germinate
synergism/antagonism
:
The degree to which hormones work
together/against one another
leaf loss in deciduous plants :
Response to abiotic stress
Photoperiodism the
degree to which plants are sensitive to a lacu of light
·
:
falling light levels s fall in auxin Athene
produce
and
Abcission zone Ethere causes
switching digest the cell wall in the
·
gene encymes
:
bundles
separation layer ·
fatly deposits also form a
waterproof scar in the vascular
blood
freezing Chemicals in the
cytoplasm raise the
freezing point in winter
:
Stomatal Control :
1
ABA opens ion channels
2 .
Caltions enter the
cytosol
3 . This establishes a conc .
gradient so water leaves the guard cens ->
Closing the stomata
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