1. Chapter 25 Plant Responses and Adaptations.

2. Set Up Foldable Tropism Phototropism Geotropism Thigmotropism
Fold Long and Skinny (hotdog)
Fold short and fat 2 times (hamburger)
Open so looks like below, crease is on top
Tropism
Phototropism
Geotropism
Thigmotropism

3. Tropism ~ a response of a plant to an environmental stimulus.
What is a tropism?
Tropism ~ a response of a plant to an environmental stimulus.

4. Tropism
Tropism is growth in response to an external stimulus (factor that elicits a response).
Positive tropism: Plant growth toward a stimulus (water, sunlight)
Negative tropism: Plant growth away from a stimulus (spilled gas, toxins, too much sun or not enough)

5. Phototropism ~ a tendency of plants to grow toward a source of light.
What is phototropism?
Phototropism ~ a tendency of plants to grow toward a source of light.

6. Phototropism
Phototropism is a change in the growth of a plant in response to light.
The stalk displays positive phototropism growing towards the light.

7. What is gravitropism?
Gravitropism ~ a tendency of a plant to grow in a direction in response to the force of gravity.

8. Thigmotropism ~ the response of plants to touch.
What is thigmotropism?
Thigmotropism ~ the response of plants to touch.

9. Geotropism (Gravitropism)
Geotropism is a change in the growth of a plant in response to gravity.
The stalk displays a negative geotropism growing away from gravity.
The roots display a positive geotropism growing towards gravity.

10. Hydrotropism
Hydrotropism is a change in the growth of a plant in response to water.
The roots display a positive hydrotropism growing towards water.

11. Turgor Pressure http://www.kscience.co.uk/animations/turgor.htm
Click on link above for example

12. No Water
Some Water
Full of Water

13. No Turgor Pressure Low Turgor Pressure Full Turgor Pressure Plant is
dead.
Plant is
wilted.
Plant is
healthy / balanced.
The cell is flaccid.
The vacuole does not
have a lot of water in it.
The vacuole and cell wall push against each other.
The vacuole is now full of water.
The cell’s vacuole does not have any water in it.