PLANT TROPISM
Objectives
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Identify tropisms in plants.
Examine effects of tropisms in plants.
Recall differences in tropisms and effects of
tropisms in plants.
What is Tropism?
A growth movement whose
direction is determined by the
direction of the stimulus.
■ Tropisms cause a change in
growth pattern.
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Negative & Positive Tropisms
1. Negative Tropism
2. Positive Tropism
Positive Tropism
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Grows in the direction from
which the stimulus originates .
Growth toward
the sun.
Negative Tropisms
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Growth away from the stimulus.
Growth away from
gravity.
http://www.cccmkc.edu.hk/~sbj-biology/AL%20BIO/Continuity%20of%20life%20growth%20and%20development/Growth%20and%20development_image/Tropism_
image/Phototropism%20in%20mung%20bean%20seedling.jpg
4 TYPES OF TROPISMS
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Phototropism
Geotropism
Hydrotropism
Thigmotropism
PHOTOTROPISM
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Response to light
GEOTROPISM or
GRAVITROPISM
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Response to gravity
HYDROTROPISM
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Response to water
THIGMOTROPISM
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Response to touch
Summary
What is a tropism?
■ A growth movement towards a stimulus.
4 Types of Tropisms
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Phototropism-growth toward light.
■Geotropism-growth due to gravity.
■Hydrotropism-growth toward water.
■Thigmotropism -growth due to touch.
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