the tempest your subtitle goes here unit 4 – lesson 3 notes plant responses
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THE TEMPEST
Your Subtitle Goes HereUnit 4 – Lesson 3 Notes
Plant Responses
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• Your Subtopics Go HerePlant Responses
• Changes resulting from internal and external stimuli.
– Tropism– Hormones– Photoperiodism
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• Your Subtopics Go HereTropism• A response to a stimulus resulting in growth
change; can be positive (toward stimulus) or negative (away from stimulus).
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• Your Subtopics Go HereTropism– Some plants grow around objects they touch.
• Thigmotropism
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• Your Subtopics Go HereTropism– Plants may grow toward a light source.
• Phototropism
– Gravity – downward growth of roots is a positive response; upward growth of stem is a negative response.
• Gravitropism
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• Your Subtopics Go HerePlant Hormones
• They control growth changes triggered by tropisms.
– Ethylene – gas produced by many plants and released into the air.
• Can promote cell growth between leaf and stem resulting in leaf drop.
• Stimulates fruit ripening process.
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• Your Subtopics Go HerePlant Hormones– Auxin – helps with stem elongation and root formation
• Auxin causes plants to bend toward the light.
– Gibberellins – assists with plant germination and development
– Cytokinins – also cause fast growth through rapid cell division.
– Abscisic acid – slows or stops plant growth.
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• Your Subtopics Go HerePhotoperiodism• Plants sensitivity to daily hours of light and darkness for flower
production
– Long-day plants – need less than 10-12 hours of darkness to produce flowers.
Carnation
Pea Plant
Wheat
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• Your Subtopics Go HerePhotoperiodism
– Short-day plants – want 12 or more hours of darkness to produce flowers.
Strawberry
Coffee Plant
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• Your Subtopics Go HerePhotoperiodism
– Plants that can flower within any range of darkness hours are called day-neutral plants.
Cucumber Roses Tomato
THE TEMPEST
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Life
Watch 15 minutes of Discovery’s LIFE. Can you identify different types of tropism?https://www.youtube.com/watch?v=wwgbHesIwxk