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19 Cards in this Set
- Front
- Back
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Thigmotropism
Right: tendrils of the bur cucumber Cucumis anguria |
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Diurnal movement of wood sorrel leaves, Oxalis
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Chrysanthemum, a short-day plantLeft: short-day conditions; right: long-day conditions
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Morphogenic response of Poinsettia (flower formation) to short days
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Spinach, a long-day plantLeft: short-day conditions; right: long-day conditions
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Etiolated seedling needs exposure to red light to turn green
Etiolation: plant that is dark-grown, or under soil is thin and pale. They become green and sturdier when exposed to red light. Exposure to far-red light will cancel the effect |
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Thigmonastic movement (after touching) in Mimosa pudica
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Venus flytrap thigmonastic movment
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Thigmomorphogenesis
Regular rubbing inhibits elongation, but promotes radial expansion of plants Left Arabidopsis plant was rubbed. |
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Heliotropism (of lupine)Leaves move and stay perpendicular to sun’s rays
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Heliotropism (solar tracking) of sunflowers
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Tropism
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Bending of plant towards or away from stimulus
Positive: towards stimulus Negative: away from stimulus |
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1. Phototropism
2. Gravitropism: 3. Hydrotropism: 4.Thigmotropism: |
1.movement because of light
2.in response to gravity 3. in response to moisture 4. in response to touch |
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The Floral Stimulus
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Florigen is the flowering substance.
It is formed in mature leaves and transported through the phloem to the apical meristem where it triggers a series of gene activities leading to flowers. Florigen production seems to be dependent on day length. |
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Vernalization
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Vernalization is exposure of plants to cold.
Needed for some plants to flower. Takes place in shoot of apical meristem Required for many biennials, winter annuals (sown in fall, bloom next spring) |
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Dormancy
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Special condition of arrested growth.
Growth resumes when limiting conditions disappear What are the triggers for growth for buds, seeds? There are endogenous inhibitors that must be removed. |
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Seeds and dormancy
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Environmental cues to break dormancy:
Warm temperatures after a long period of cold Exposure to moisture after a period of drying Abrasion by soil activities wearing away a protective coat: scarification Microbial digestion of seed coat Leaching away of inhibitory chemicals Some seeds remain viable for a long time: a 2000 year old date palm; a 1300 year old lotus |
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1. Nastic movements
2. Nyctinastic movement 3. Thigmonastic movements 4. Photonastic 5. Morphogenic responses 6. Taxis 7. Thigmomorphogenesis 8. Heliotropism |
1. non-growth response, no orientation with regard to direction of stimulus
2. sleep movement of leaves, vertical at night 3. (turgor changes) 4. opening and closing of flower parts: diurnal or nocturnal 5. fundamental changes in plants life stages (vegetative > reproductive) 6, cell swimming away from or towards stimulus (sperm cells of algae and some plants) 7. altering growth patterns: touching increases radial growth 8. solar tracking |
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Pulvinus
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thickening at the base of plant parts that show nastic movements. Turgor change in parenchyma cells cause movement
Example: Mimosa pudica |