Plant Physiology (Biology 327)  - Dr. Stephen G. Saupe;  College of St. Benedict/ St. John's University;  Biology Department; Collegeville, MN  56321; (320) 363 - 2782; (320) 363 - 3202, fax;    ssaupe@csbsju.edu

Exam Questions: Plant Responses to the Environment

1. Explain why roots grow down and shoots grow up [include signal, receptor (nature, location), transducing mechanism, response]. Or, in other words, how does gravitropism work? Provide evidence to support your response.
    
2. Explain why shoots bend toward the light (include signal, receptor, transducing mechanism, response). Or, in other words, how does phototropism work? Provide evidence to support your response.
    
3. Phytochrome is a pigment responsible for a variety of photomorphogenic responses in plants. Describe the photochemical and biochemical properties of phytochrome. Include in your response such topics as nature of the protein, chromophore, conformational/chemical changes, regulation, localization in the plant. Also include a discussion of the three major phytochrome-mediated responses and provide an example of each.
    
4. Describe the sequence of events necessary for a plant to flower. (hints: ripeness to flower, juvenility, apex changes). Then describe vernalization. Include a discussion of stimulus, receptor, transducing mechanism (including hormone(s) involved) and physiological response.
    
5. Discuss photoperiodism including stimulus, receptor and transducing mechanism. Where appropriate provide evidence to support your response.
    
6. Describe the physiological strategies used by spring wildflowers to survive conditions in the spring.