11 plant behaviour
TRANSCRIPT
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Plant Behaviour
External factors, such as light, gravity and
touch have an influence on plant growth
and development.
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Plant Behaviour
External factors, such as light, gravity and
touch have an influence on plant growth
and development.
The growth of a plant in response to a
stimulus such as light or water is called a
tropism.
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Types of TropismTypes of Tropism
stimulusgravity
tropism
response
shoot
root
geotropism
negative
positive
unilateral light
phototropism
positive
negative
water
hydrotropism
no response
positive
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Tropisms
Growth of a plant in a specific DIRECTION
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Tropisms
Growth of a plant in a specific DIRECTION
Positive tropism =TOWARDS THE
STIMULUS
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Tropisms
Growth of a plant in a specific DIRECTION
Positive tropism =TOWARDS THE
STIMULUS
Negative tropism =AWAY FROM THE
STIMULUS
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Importance of PhototropismImportance of Phototropism
Enables leaves to be in a position to
receive as much sunlight as possible for
photosynthesis
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Tropisms
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Auxin
Commonest plant hormones
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Auxin
Commonest plant hormones
Regulates growth & other physiological
processes in plants
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Auxin
Commonest plant hormones
Regulates growth & other physiological
processes in plants
Produced by root tip / shoot tip
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Auxin
Commonest plant hormones
Regulates growth & other physiological
processes in plants
Produced by root tip / shoot tip
They affect the elongation region of the tip
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Auxin
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Auxin
If light is concentrated on one side of the
plant, then auxin moves awayfrom the
light source to the darker side of the tip
and becomes more concentrated in thecells in that region.
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Auxin
If light is concentrated on one side of the
plant, then auxin moves awayfrom the
light source to the darker side of the tip
and becomes more concentrated in thecells in that region.
The increased concentration of auxin
means they grow more quickly than cellsnearer the light.
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Auxin
If light is concentrated on one side of theplant, then auxin moves awayfrom thelight source to the darker side of the tip
and becomes more concentrated in thecells in that region.
The increased concentration of auxinmeans they grow more quickly than cellsnearer the light.
The uneven growth results in the bending
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Phototropism in ShootPhototropism in Shoot
The shoot tip produces auxin which diffuse
downward
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Phototropism in ShootPhototropism in Shoot
The shoot tip produces auxin which diffuse
downward
The auxin diffuse to the
shaded side due to the presence
of unilateral light
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Phototropism in ShootPhototropism in Shoot
The shoot tip produces auxin which diffuse
downward
The auxin diffuse to the
shaded side due to the presence
of unilateral light
High auxin concentrationstimulates growth in shoot
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Phototropism in ShootPhototropism in Shoot
The shoot tip produces auxin which diffuse
downward
The auxin diffuse to the
shaded side due to the presence
of unilateral light
High auxin concentration
stimulates growth in shoot The shaded side grows
fasterthan the lighted side
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Phototropism in ShootPhototropism in Shoot
The shoot tip produces auxin which diffuse downward
The auxin diffuse to the
shaded side due to the presence
of unilateral light
High auxin concentrationstimulates growth in shoot
The shaded side grows
fasterthan the lighted side
The shoot bends towards
the light
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Geotropism in RootGeotropism in Root
The root tip produces
auxin which diffuse to
the elongation region
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Geotropism in RootGeotropism in Root
The root tip produces
auxin which diffuse to
the elongation region
The auxin diffuse tothe lower side due to
gravity
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Geotropism in RootGeotropism in Root
The root tip produces
auxin which diffuse to
the elongation region
The auxin diffuse tothe lower side due to
gravity
High auxin
concentration inhibits
growth in root
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Geotropism in RootGeotropism in Root
The root tip produces
auxin which diffuse to the
elongation region
The auxin diffuse to the
lower side due to gravity
High auxin concentration
inhibits growth in root
The lower side grows
slowerthan the upper
side
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Geotropism in RootGeotropism in Root
The root tip producesauxin which diffuse to theelongation region
The auxin diffuse to the
lower side due to gravity High auxin concentration
inhibits growth in root
The lower side growsslowerthan the upperside
The root bendsdownward
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The End