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Plants in Motion

Plants in Motion. Tropism in plants. Background. A stimulus is anything in the environment that causes a response in an organism. The response often involves movement either toward the stimulus or away from the stimulus. Plants respond to stimuli such as touch, light, and gravity.

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Plants in Motion

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  1. Plants in Motion Tropism in plants

  2. Background • A stimulus is anything in the environment that causes a response in an organism. • The response often involves movement either toward the stimulus or away from the stimulus. • Plants respond to stimuli such as touch, light, and gravity. • Some responses of a plant to an external stimuli are called tropisms • A tropism is generally termed “positive” if growth is toward the signal and “negative” if it is away from the signal.

  3. How Plants respond to stimuliorTropisms in Plants

  4. Geotropism • Response in plants to respond to gravity. • The stem/shoots show negative tropism. (Against gravity.) • The roots show Positive (towards gravity.)

  5. Importance of Geotropism • provide firm anchorage for roots. • ensure the plant can get adequate supply of water & mineral salts Picture from http://cbse.myindialist.com/biology-x-control-and-coordination-coordination-in-plants-movement-due-to-growth/

  6. Phototropism • Response to light. • When a plant grows toward light it is called a positive response to light, or positive phototropism

  7. Importance of Phototropism • enables leaves to be in a position to receive as much sunlight as possible for photosynthesis Picture from http://herbarium.desu.edu/pfk/page11/page12/page13/page13.html

  8. Hydrotropism • Response to water. • Example: plants moving to a higher humidity, roots moving to a greater concentration of water.

  9. Importance of Hydrotropism • ensures that a plant gets enough water as a raw material for photosynthesis & enough mineral salts to maintain normal growth Picture from http://www.tutorvista.com/content/biology/biology-iv/plant-growth-movements/paratonic-movements.php

  10. Thigmotropism • Response to touch. • The stem bends and twists around any object it touches.

  11. Importance of Thigmotropism • Gives the plant additional support. Picture from http://wikipedia.com

  12. Nastic Movement • Rapid response of rapid movements of plant organs in response to a stimulus • Used as a defense. • Used to trap its prey in carnivorous plants. Picture from http://www.sunnysidescience.com/plant_responses.htm Picture from http://cdn-write.demandstudios.com/upload/1000/600/10/8/391618.jpg

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