| Signal Transduction and Plant Responses |
| 1. |
Compare the growth of a plant in darkness (etiolation) to the characteristics of greening (de-etiolation). |
| 2. |
Describe the signal pathways associated with de-etiolation. |
| 3. |
Describe the role of second messengers in the process of de-etiolation. |
| 4. |
Describe the two main mechanisms by which a signaling pathway can activate an enzyme. |
| 5. |
Explain, using several examples, what researchers have learned about the activity of plant hormones by study of mutant plants. |
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Plant Responses to Hormones |
| 6. |
For the following scientists, describe their hypothesis, experiments, and conclusions about the mechanism of phototropism:
a. Charles and Francis Darwin
b. Peter Boysen-Jensen
c. Frits Went |
| 7. |
List six classes of plant hormones, describe their major functions, and note where they are produced in the plant. |
| 8. |
Explain how a hormone may cause its effect on plant growth and development. |
| 9. |
Describe a possible mechanism for the polar transport of auxin. |
| 10. |
According to the acid growth hypothesis, explain how auxin can initiate cell elongation. |
| 11. |
Explain why 2,4-D is widely used as a weed killer. |
| 12. |
Explain how the ratio of cytokinin to auxin affects cell division and cell differentiation. |
| 13. |
Describe the evidence that suggests that factors other than auxin from the terminal bud may control apical dominance. |
| 14. |
Describe how stem elongation and fruit growth depend on a synergism between auxin and gibberellins. |
| 15. |
Explain the probable mechanism by which gibberellins trigger seed germination. |
| 16. |
Describe the functions of brassinosteroids in plants. |
| 17. |
Describe how abscisic acid (ABA) helps prepare a plant for winter. |
| 18. |
Describe the effects of ABA on seed dormancy and drought stress. |
| 19. |
Describe the role of ethylene in the triple response to mechanical stress, apoptosis, leaf abscission, and fruit ripening. |
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Plant Responses to Light |
| 20. |
Define photomorphogenesis and note which colors are most important to this process. |
| 21. |
Compare the roles of blue-light photoreceptors and phytochromes. |
| 22. |
Describe the phenomenon of chromophore photoreversibility and explain its role in light-induced germination of lettuce seeds. |
| 23. |
Define circadian rhythm and explain what happens when an organism is artificially maintained in a constant environment. |
| 24. |
List some common factors that entrain biological clocks. |
| 25. |
Define photoperiodism. |
| 26. |
Distinguish among short-day, long-day, and day-neutral plants. Explain why these names are misleading. |
| 27. |
Explain what factors other than night length may control flowering and what is necessary for flowering to occur. |
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Plant Responses to Environmental Stimuli Other than Light |
| 28. |
Describe how plants apparently tell up from down. Explain why roots display positive gravitropism and shoots exhibit negative gravitropism. |
| 29. |
Distinguish between thigmotropism and thigmomorphogenesis. |
| 30. |
Describe how motor organs can cause rapid leaf movements. |
| 31. |
Provide a plausible explanation for how a stimulus that causes rapid leaf movement can be transmitted through the plant. |
| 32. |
Describe the challenges posed by, and the responses of plants to, the following environmental stresses: drought, flooding, salt stress, heat stress, and cold stress. |
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Plant Defense: Responses to Herbivores and Pathogens |
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| 33. |
Explain how plants deter herbivores with physical and chemical defenses. |
| 34. |
Describe the multiple ways that plants defend against pathogens. |
