Chapter 25 Plant Responses and Adaptations.

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Chapter 25 Plant Responses and Adaptations.
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Set Up Foldable

• 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
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What is a tropism?

• Tropism a response of a plant to an
  environmental stimulus.

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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)

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What is phototropism?

• Phototropism a tendency of plants to grow
  toward a source of light.

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Phototropism

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

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What is gravitropism?

• Gravitropism a tendency of a plant to grow in a
  direction in response to the force of gravity.

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What is thigmotropism?

• Thigmotropism the response of plants to touch.

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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.

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Hydrotropism

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

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Turgor Pressure

• http//www.kscience.co.uk/animations/turgor.htm
• Click on link above for example

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