Plant Physiology: Hormones & Responses to the environment; Lecture week Feb. 18-22 Learning Objectives: • Explain the importance of phytochrome in plant responses to light environment. • Define hormone and explain its general role. • List the well-documented roles of each of the major hormone groups in plant development and responses to environment. Discussion Questions: The questions below are required to be prepared for discussion but are not going to be graded. 1. What is phytochrome? On what basic principle(s) does it operate? Differentiate between the P r fr forms. A phytochrome is a photoreceptor that plants use to detect light. It exists in two forms: P r (red) and P fr (far red). The difference in these forms caused by the absorbance of different wavelengths of light can signal to the plant the time of day as well as seasonal changes. 2. List the major types of hormones found in plants. For each, describe one situation or name a developmental process where they are involved. Auxins-tropisms
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