2. What are 3 types of tropism?
Tropo means what?
What is tropism?
What are 3 types of tropism?
In a diagram, show what positive geotropism is.
In a diagram, show what negative geotropism is.
What is good about geotropism? (Why is it important to a plant?)
What does photo mean?
Where have you noticed phototropism?
What kind of plants exhibit thigmotropism?
In addition to positive geotropism, what kind of tropism do a plant’s roots show?
How do you think the capital N tree formed such a remarkable shape?

3. TROPISM
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4. TROPISM Plant growth in response to a stimulus
(“tropo” – ”turn”) .
There are many types of tropisms :
Phototropism
Geotropism
Thigmotropism
Hydrotropism
Chemotropism
Thermotropism
3 main types
*Can be positive or negative
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5. Geotropism is the growth of a plant in response to gravity.
(“Geo” – Earth)
Geotropism is the growth of a plant in response to gravity.
Negative Geotropism
Negative Geotropism
It is the growth of a plant away from the center of the earth--opposite from the pull of gravity
Ex. stems grow up
Positive Geotropism
It is the growth of a plant towards the center of the earth--down with gravity.
Ex. roots growing down
Positive Geotropism
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6. IMPORTANCE OF GEOTROPISM
Pulls roots down to anchor a plant
Roots can get needed water and
minerals if they stay in the soil
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7. CORN TROPISM LAB

8. Ex. Stems growing toward the window to get to the light
PHOTOTROPISM
(“Photo” – light)
The growth response of a plant in response to light direction is called phototropism.
Ex. Stems growing toward the window to get to the light
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10. IMPORTANCE OF PHOTOTROPISM
Enables leaves to be in the best position possible to receive adequate light for photosynthesis
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11. Thigmotropism is the growth of a plant in response to touch/contact.
(“Thigmo” – “touch”)
Thigmotropism is the growth of a plant in response to touch/contact.
Photo by Christopher Meloche
Tendrils on a sweet pea
Vines growing on a wall or fence
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12. SOME OTHER
TYPES OF
TROPISM
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13. Chemotropism THERMOTROPISM HYDROTROPISM
(“Therm” – “heat”)
Thermotropism is the tendency of plants or other organisms to bend toward or away from heat.
Ex. curling of Rhododendron leaves in response to cold temperatures.
HYDROTROPISM
(“hydro” – “water”)
Hydrotropism is the growth in response to water. Ex. roots growing toward moisture
Chemotropism
(“Chemo” – chemical”)
Chemotropism is movement caused by chemical stimuli. Ex. Growth of a pollen tube is always towards the ovules
so that reproduction can occur
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14. Geotropism happened here!

15. The N Tree. This tree is on a trail near Salem Lake.
Mr. Anderson always has to duck when he rides underneath it.

16. Answer: By comparing to growth of the ________________ seeds.
Back to our E.Q.--How can you find out how experimental (treated) tomato seeds grow?
Key word: experimental
Answer: By comparing to growth of the ________________ seeds.
(You always need a control.)
control (untreated)