Plant Responses to Internal and External Signals

1.  What are hormones?

2.  Know the major types of plant hormones, where they are produced in the plant, and their major roles in plant physiology.

3.  Explain how auxin controls cell expansion.

4.  What occurs during leaf abscission, and why do leaves change color in the fall?

5.  What are tropisms, and what are the differences among phototropism, gravitropism, and thigmotropism?

6.  Describe some plant functions that are controlled on a daily basis.  On a seasonal basis.

7.  What are circadian rhythms, and how do they influence plant function on a daily basis?

8.  What is photoperiodism and how does it influence plant function on a seasonal basis? What environmental stimulus controls photoperiodism?  Would you expect photoperiodism to be more important to a temperate or tropical plant?  Explain.

9.  Describe the role of phytochrome pigments in controlling plant response to photoperiod.

10.  Incorporating all that you know about plant structure and function (metabolic, morphological, physiological, hormonal etc...), explain how plants cope with water deficit.