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Topic : Plants Aim : Describe the role of tropisms in plants. Do Now : Explain the function of each part of a plant. HW :. ..videosVenus_Flytrap__Deadly_Meal.wmv. What is a tropism?. Plant response to an external stimulus Positive tropism = grows toward stimulus
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Topic: Plants Aim: Describe the role of tropisms in plants. Do Now: Explain the function of each part of a plant. HW:
What is a tropism? Plant response to an external stimulus Positive tropism = grows toward stimulus Negative tropism = grows away from stimulus
What are auxins? Plant hormones Affect the growth of plant tissue
Phototropism Tendency of plant to grow towards the light (stimulus)
Cells on side opposite the light get longer (caused by auxins) Uneven growth, the plant bends towards the light
Geotropism Plant response to gravity
Thigmotropism • Plant response to touch • Positive tropism http://www.youtube.com/watch?v=_SIJ4ov_FxA
Hydrotropism • Plant response to water • Positive tropism
Let’s summarize…. • Describe tropisms. • What are some examples of external stimuli that cause tropisms? • Explain phototropism. • Explain geotropism. • Explain thigmotropism. • Explain hydrotropism
Plant substances that affect plant growth are called • tropisms • glucose • germination • hormones
Plant response to a stimulus is called • photosynthesis • transpiration • tropism • locomotion
An example of a negative tropism is • stems growing up and away from gravity • plants bending towards light • roots growing down towards gravity • Plants growing towards a water source