1. Plant Response to Stimuli Mechanisms plants have to respond to environmental stimuli

2. How do plants respond to stimuli!  They don’t get up and run away!  They do:  Have tropisms in response to:  Light, Gravity, Touch  Have defense against pathogens  Have hormones that initiate signal transduction pathways to send messages long-distance.

3. Responses to light  Phytochromes:  Phototropism:  Phytochromes can initiate hormones that promote growth toward light (more later…)  Circadium rhythm(daily)  4 o’clock flowers = to sleep cycle in animals  Photoperiodism (seaonally)  Season for flowering:  Short day plants vs. long day plants…when would be the best time to flower in New England if…

4. Circadian Rhythm

5. Photoperiodism

6. Plant hormone experimental presentation!  Find an experiment involving your plant hormone:  Introduction —What is your hormone used for?  Hypothesis —What was the researchers hypothesis?  Methods —How did the researcher collect data.  Data —Find a picture or graph to analyze results and explain a verbal trend.  Conclusion —What did the experimenters learn about the plant hormones.

7. Hormones to be familiar with:  Auxin  Abscisic acid  Cytokinins  Ethylene  Gibberellins