In depth revision notes covering the whole of plant and animal responses. The topic is broken down into the individual specification points, shown by the numbers used throughout.
This helps them
to survive for
longer-greater
chance of them
J
- reproducing
RESPONSES TO ABIOTIC STRESS
Alkaloids-nitrogenous
J
butter tasting
metabolism
S
compounds that interfere with
,
E .
g Caffere toxic to fungit visects
!
.
Tannins-bitter tasting puenoic compounds
that buid to digestive enzymes produced wi
Saliva viactivate them . t .
g . tea
.
pheromones chemicals released
-
that
affect behaviour of other members of
Whe same species
.
↳ E .
.
g If a maple tree is attacked by
insects ,
it releases pheromones which are
absorbed by the leaves on other .
branches
This causes the leaves to make callose
to protect them S
Mimosa Pudica is a plant that folds
&
un response to touch It contals an .
alkaloid The stem has sharp prickles
.
If the leaves are touched , they collapse,
frightening large herbivores dislodging
Small visects which have landed on the
leaves The leaf recovers .
after 10 muintes
because of potassium ion is water
movement -
This is a nastic response (non-
directional) .
TROPISMS = directional response to stimuli
·
phototropism = growth in response to light
·
geotropism : growth in response to gravity
·
chemotropism = growth hi response to chemicals
·
Thigmotropism = growth in response to
touch
, Darwin's investigations
into phototropism
② If thetip
~is
of
cut
the shoot
off the
①shoots light -
is still
,
sunung ou
normally it , but i
grow doesn't bend .
towards ↳ So, the tip
right of the Shoot
must detect
Light or
Y
Produce
aux wi
⑤
If the Shoot
Boysen-Jensen's -
his is covered
,
the Shoot
investigations into
doesn't bend
.
phototropism So it must be
unowed
-
un the
detection of
-O when we
Light
put the mica
on the suaded
side the shoot ,
didn't bend &
because anxu
-
C
2
Couldn't pass
down the
shaded side +
⑪ cause
elongation
A thin layer
of mica (material
that blocks movement ③ Gelatin allows
of chemical messengers)
chemical messengers
was put on the to pass through .
tip
S
the shoot
uminated side of The of
wasout off
the shootI it bend towards &
gelatin was placed
the light on top of the cut
Shoot , and tip
replaced (put&
on top
of genatur) ,
when
right was shone on
Mis the shoot bent
towards light
↳ this is because
The auxai could pass -
through the gelati
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