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Tropism: The Way Plants Respond to Stimuli

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Presentation on theme: "Tropism: The Way Plants Respond to Stimuli"— Presentation transcript:

1 Tropism: The Way Plants Respond to Stimuli
Presentation Created by Mr. M. Barr, Kleb Intermediate School With Adaptations by D. Tresten, Schindewolf Certain materials are included under the fair use exemption of the U.S. Copyright Law and have been prepared according to the multimedia fair use guidelines and are restricted from further use.

2 Stimulus (pl. Stimuli): Cause
Response: Effect

3 Light All plants respond to light Stems and leaves grow toward light
Response to light is phototropism

4 Gravity The response to gravity is called geotropism (or gravitropism)
We do not need to worry about which way to plant a seed because the root grows down and the stem grows up. Why does this happen? It happens because plants respond to the pull of gravity. Root cells grow toward the pull of gravity; stem and leaf cells grow away from the pull of gravity. The response to gravity is called geotropism (or gravitropism)

5 Water A plant’s roots grow toward water (not very strongly; plant must be touching water) Growth of a plant’s roots toward water is called hydrotropism

6 Touch Some plants respond when they are touched
Grapevines,etc. have tendrils which allow a plant to grow around an object Response of a plant to touch is thigmotropism

7 Color Plants respond to different colors of light
Response of a plant to color is chromotropism

8 Heat Plants respond to different temperatures
Response of a plant to temperature changes is called thermotropism

9 Examples View the following slides for examples of tropism
(some of which are also called nastic movements)

10 View videos of Tropism Go to

11 View animation of Phototropism

12 REVIEW

13 Source: http://www.afpmb.org/mpmh/chap2.htm
Forms of Tropism Know these for the test: PHOTOTROPISM -- response to light. GEOTROPISM -- response to earth contact or gravity. THERMOTROPISM -- response to heat. HYDROTROPISM -- response to moisture. CHROMOTROPISM -- response to colors. THIGMOTROPISM -- response to touch. Source:

14 Name the Types of Tropisms that we Learned
Clue: Water VS No water Clue: Heat VS Cold Clue: Close VS Far from Earth Clue: Touch with a toothpick Clue: Blue light VS Red light Clue: Dim light VS Bright light Hydrotropism Thigmotropism Thermotropism Chromotropism Phototropism Geotropism/Gravitropism

15 Click when you know the answer:
Tropism Definition: Response to light Response to heat Response to gravity Response to moisture Response to touch Response to colors Phototropism Thermotropism Gravitropism or Geotropism Hydrotropism Thigmotropism Chromotropism

16 Geotropism/Gravitropism Gravitropism or Geotropism
Try again: Hydrotropism Thigmotropism Thermotropism Chromotropism Phototropism Geotropism/Gravitropism Tropism Definition: Response to touch Response to water Response to colors Response to cold Response to gravity Response to too little light Thigmotropism Hydrotropism Chromotropism Thermotropism Gravitropism or Geotropism Phototropism

17 Name the type of Tropism that each of the following investigations is testing…

18 Investigation # What form of tropism is being tested?
Mesh Divider (Inserted to bottom of pan) Watered Soil Dry Soil Chromotropism Geotropism Hydrotropism Phototropism Thigmotropism Seeds =

19 Investigation # What form of tropism is being tested? Chromotropism
Geotropism Hydrotropism Phototropism Thigmotropism Thermotropism Plant B Plant A

20 # Investigation What form of tropism do you think the scientist is meaning to test? What’s wrong with the idea? Chromotropism Geotropism Hydrotropism Phototropism Thigmotropism Thermotropism

21 Investigation # What form of tropism is being tested? Phototropism
Thigmotropism Thermotropism Chromotropism Geotropism Hydrotropism Purple light White Light

22 Investigation # What form of tropism is being tested? Chromotropism
Geotropism Hydrotropism Phototropism Thigmotropism Thermotropism

23 Investigation # What form of tropism is being tested?
Chromotropism Geotropism Hydrotropism Phototropism Thigmotropism Plant in the space shuttle Roots grow in every direction Same kind of plant in a building on Earth Roots grow downward

24 Investigation # What form of tropism is being tested? Chromotropism
Geotropism Hydrotropism Phototropism Thigmotropism Thermotropism

25 Investigation # What form of tropism is being tested? Chromotropism
Geotropism Hydrotropism Phototropism Thigmotropism Thermotropism

26 See animation and more facts:
# Investigation What form of tropism is being tested? Chromotropism Geotropism Hydrotropism Phototropism Thigmotropism Thermotropism See animation and more facts:

27 Investigation # What form of tropism is being tested?
Are there too many variables in this test? Chromotropism Geotropism Hydrotropism Phototropism Thigmotropism Thermotropism

28 Investigation # What form of tropism is being tested?
Could there be more than one variable affecting the outcome of this test? Chromotropism Geotropism Hydrotropism Phototropism Thigmotropism Thermotropism

29 Quiz Number from 1 – 15 Identify the types of tropism

30 This is an example of which form of tropism?
#1 This is an example of which form of tropism? Chromotropism Geotropism Hydrotropism Phototropism Thigmotropism Thermotropism

31 #2 Chromotropism Geotropism Hydrotropism Phototropism Thigmotropism Thermotropism Mimosa plants contract when touched. This is an example of what form of tropism?

32 #3 For a Humorous Animation of “Venus Pie Trap,” go to Venus fly traps close around insects that “irritate” them. This is an example of what form of tropism? Source & For more information, go to:

33 Investigation #4 What form of tropism is being tested if this bag is taped to a wall? Chromotropism Geotropism Hydrotropism Phototropism Thigmotropism Ziplock baggie, open at top Paper Towel, moist 1 of 2 seeds 1 is right side up/ other is upside down (lima beans, peas, corn) Staples to keep beans from moving

34 Data for Investigation 1: What evidence suggests geotropism?
#5 Data for Investigation 1: What evidence suggests geotropism? Close-up View

35 Investigation #6 What form of tropism is being tested?
Mesh Divider (Inserted to bottom of pan) Watered Soil Dry Soil Chromotropism Geotropism Hydrotropism Phototropism Thigmotropism Seeds =

36 Investigation #7 What form of tropism is being tested? Phototropism
Thigmotropism Thermotropism Chromotropism Geotropism Hydrotropism Plant A Plant B

37 Investigation #8 What form of tropism is being tested? Chromotropism
Geotropism Hydrotropism Phototropism Thigmotropism Thermotropism

38 Investigation #9 What form of tropism is being tested? Chromotropism
Geotropism Hydrotropism Phototropism Thigmotropism Thermotropism

39 Investigation #10 What form of tropism is being tested? Chromotropism
Geotropism Hydrotropism Phototropism Thigmotropism Thermotropism

40 See animation and more facts:
#11 Investigation What form of tropism is being tested? Chromotropism Geotropism Hydrotropism Phototropism Thigmotropism Thermotropism See animation and more facts:

41 Investigation #12 What form of tropism is being tested? Chromotropism
Geotropism Hydrotropism Thigmotropism Thermotropism

42 Investigation: #13 What form of tropism is being tested? Chromotropism
Geotropism Hydrotropism Phototropism Thigmotropism Thermotropism

43 Investigation #14 What form of tropism is being tested?
Chromotropism Geotropism Hydrotropism Phototropism Thigmotropism Thermotropism Plant in the space shuttle Same kind of plant in a building on Earth

44 Investigation What form of tropism is being tested? It’s hard to tell, isn’t it? Too many variables! Plant on the moon Chromotropism Geotropism Phototropism Thigmotropism Thermotropism

45 Investigation #15 What form of tropism is being tested? Chromotropism
Geotropism Hydrotropism Phototropism Thigmotropism Thermotropism

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