THE TEMPEST Your Subtitle Goes Here Unit 4 – Lesson 3 Notes Plant Responses

YOUR TOPIC GOES HERE Your Subtopics Go Here Plant Responses Changes resulting from internal and external stimuli. –Tropism –Hormones –Photoperiodism

YOUR TOPIC GOES HERE Your Subtopics Go Here Tropism A response to a stimulus resulting in growth change; can be positive (toward stimulus) or negative (away from stimulus).

YOUR TOPIC GOES HERE Your Subtopics Go Here Tropism –Some plants grow around objects they touch. Thigmotropism

YOUR TOPIC GOES HERE Your Subtopics Go Here Tropism –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

YOUR TOPIC GOES HERE Your Subtopics Go Here Plant 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.

YOUR TOPIC GOES HERE Your Subtopics Go Here Plant 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.

YOUR TOPIC GOES HERE Your Subtopics Go Here Photoperiodism Plants sensitivity to daily hours of light and darkness for flower production –Long-day plants – need less than hours of darkness to produce flowers. Carnation Pea Plant Wheat

YOUR TOPIC GOES HERE Your Subtopics Go Here Photoperiodism –Short-day plants – want 12 or more hours of darkness to produce flowers. StrawberryCoffee Plant

YOUR TOPIC GOES HERE Your Subtopics Go Here Photoperiodism –Plants that can flower within any range of darkness hours are called day-neutral plants. CucumberRosesTomato

THE TEMPEST Your Subtitle Goes Here Life Watch 15 minutes of Discovery’s LIFE. Can you identify different types of tropism?