Plant Tropisms. What are we talking about? Tropism - directional growth of a plant, or part of a...
-
Upload
william-weaver -
Category
Documents
-
view
218 -
download
1
Transcript of Plant Tropisms. What are we talking about? Tropism - directional growth of a plant, or part of a...
Plant TropismsPlant Tropisms
What are we talking about?What are we talking about?
Tropism - directional growth of a plant, or Tropism - directional growth of a plant, or part of a plant, in response to an external part of a plant, in response to an external stimulusstimulus
What are we talking about?What are we talking about?
Stimulus – Stimulus – an action or condition that an action or condition that causes a responsecauses a response
Response – Response – an action or condition that is a an action or condition that is a reaction to a stimulusreaction to a stimulus Negative responseNegative response – when the growth of a – when the growth of a
plant is away from the stimulusplant is away from the stimulus Positive responsePositive response – when the growth of the – when the growth of the
plant is towards the stimulusplant is towards the stimulus
Types of TropismTypes of Tropism
We are going to be studying 6 Tropisms:We are going to be studying 6 Tropisms:
HydrotropismThermotropism
Gravitropism
Thigmotropism
Phototropism Heliotropism
HydrotropismHydrotropism
Stimulus: Stimulus: WaterWater
Response: Response: A plant’s roots grow towards A plant’s roots grow towards the source of waterthe source of water Is this a positive or negative response? Is this a positive or negative response?
ThermotropismThermotropismStimulus: Stimulus: TemperatureTemperatureResponse: Response: a plant grows in the direction of/away from a a plant grows in the direction of/away from a source of heat or coldsource of heat or cold Example: In the first picture, this tree has a Example: In the first picture, this tree has a positivepositive response to response to
the coldthe cold.. Example: A plant called a Rhododendron curls its leaves Example: A plant called a Rhododendron curls its leaves awayaway
when it experiences when it experiences cold weathercold weather..
GravitropismGravitropism
Stimulus: Stimulus: GravityGravity
Reaction:Reaction: Positive – Positive – the roots the roots
grow downward, with grow downward, with gravitygravity
Negative – Negative – the stalk the stalk grows upward, against grows upward, against gravitygravity
ThigmotropismThigmotropism
Stimulus: Stimulus: TouchTouchResponse – Response – the leaves the leaves (or part of the plant that (or part of the plant that is touched) move or coil is touched) move or coil away from the touch, or away from the touch, or trigger some other actiontrigger some other action Example: The Venus Fly Example: The Venus Fly
Trap is a plant that shows Trap is a plant that shows thigmotropism. thigmotropism. It closes It closes when a bug or some other when a bug or some other object touches it. object touches it.
PhototropismPhototropism
Stimulus: Stimulus: LightLightResponse – Response – the plant grows in the the plant grows in the direction of a unidirectional light (it only direction of a unidirectional light (it only comes from one direction)comes from one direction) What type of response is this? What type of response is this?
HeliotropismHeliotropismStimulus: Stimulus: SunlightSunlightResponse – Response – a plant grows or turns to face the direction of a plant grows or turns to face the direction of the sunthe sun Example: Example: Young Sunflowers face the sun all day long. As the sun Young Sunflowers face the sun all day long. As the sun
goes across the sky, the sunflower turns so that it is always facing goes across the sky, the sunflower turns so that it is always facing it. it.
Is a Sunflower growing towards the sun an example of Is a Sunflower growing towards the sun an example of Phototropism or Heliotropism? Phototropism or Heliotropism?
ReferencesReferencesPictures: http://virtualastronaut.tietronix.com/textonly/act25/images/hydrotropism.
gif
http://k53.pbase.com/u48/roving_rube/large/30489110.a.c.birch.jpg http://www2.brevard.edu/jefrick/rhod.htm http://www.xtec.cat/~mherna23/summer03/amspot/picture/gravitropism.
gif
http://img1.photographersdirect.com/img/17231/wm/pd1198793.jpg http://wpcontent.answers.com/wikipedia/commons/9/9d/Dionaea_musci
pula_closing_trap_animation.gif http://img1.photographersdirect.com/img/17231/wm/pd1198796.jpg http://farm2.static.flickr.com/1423/1402179998_4e1712d584.jpg
Information: http://www.hasc.qld.edu.au/csnotes06/biowedGG/Notes%20for
%20Sandra/Plant%20Tropisms.doc www.wikipedia.org