Lecture Outline for April 22, 2005


Topic: phototropism (sensory systems in plants)

Chapter 29 sections 29.2, 29.3

Figures used in lecture: 29.7, 29.9, 29.10, 29.11, 29.12, 29.14, 29.15

Additional Resources:

                Phototropism – discussion of early experiments, including the phototropism work of Darwin

                The Mechanisms of Phototropism


How Plants Move

Define/explain: tropism, phototropism, gravitropism, thigmotropism, nastic movements, thigmonasty, nyctinasty


Sensory System in Plants - Sensing Light

Define/explain: long-day plants, day-neutral plants, short-day plants, visible light, blue light, red light, far-red light, receptor, signal transduction, response


There are (at least) two separate photosystems in plants.  One photosystem involves the plant’s response to blue light.  The second photosystem controls the plant’s response to red and far-red light wavelengths.


You should be able to:

1.  Explain the general aspects of phototropism.

2.  Explain the difference between a long-day, day-neutral, and a short-day plant.

2. Explain the receptor and response for both of the blue light and red/far-red photosystems discussed in lecture.

3.  Explain the basic process of signal transduction.