the tempest your subtitle goes here unit 4 – lesson 3 notes plant responses

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