1 What is the primary precursor for auxin biosynthesis and where is auxin synthesized in the plant 2 Describe a typical dose response curve for auxin induced stem or coleoptile elongation What 3 What structure or structures act as gravity receptors in plant cells Where are these structures happens at high doses located in shoots and roots 4 Discuss how auxin regulates apical dominance lateral and adventitious roots leaf abscission floral bud development vascular differentiation and fruit development 5 How were gibberellins GAs discovered 6 What are the common chemical features of gibberellins and to which general class of compounds are they related 7 Briefly describe several different physiological responses to GA 8 What are some commercial applications of GA in agriculture 9 Which pathway produces the early intermediates for GA biosynthesis What three cellular compartments are involved in gibberellin biosynthesis and what are the major biochemical steps in each compartment 10 Which reactions cause gibberellin inactivation 11 GA can inhibit its own synthesis by negative feedback regulation Which steps in the GA biosynthesis pathway are down regulated by GA 12 Considering plant hormones and regulators how can plant height be altered through genetic engineering 13 The GA and phytochrome pathways are integrated Compare and contrast the GA signaling pathways in dark grown tall and light grown short Arabidopsis hypocotyls 14 The study of which cellular process led to the discovery of cytokinin Was the first discovered cytokinin a synthetic or naturally occurring hormone 15 Name two plant diseases that are associated with cytokinin overproduction In each case what is the source of the excess cytokinin 16 Compare the plant and microbial pathways of cytokinin biosynthesis What are the naturally occurring cytokinins in plants Which enzyme catalyzes the first step in cytokinin biosynthesis 17 Cytokinins can act both locally and over long distances in the plant Provide examples of both types of cytokinin action In which tissue s does long distance transport occur 18 Which enzyme is responsible for cytokinin degradation 19 Which protein or proteins represents the response regulator in the cytokinin signaling pathway What is their mechanism of action 20 Discuss the roles of cytokinins in shoot growth root growth apical dominance leaf senescence and vascular development 21 What are some potential applications of cytokinin manipulation to agriculture 22 How was the plant hormone ethylene discovered 23 Which two key enzymes are rate limiting for ethylene biosynthesis and what reactions do they 24 How is ethylene biosynthesis promoted by other hormones such as auxin and cytokinin 25 What are some specific inhibitors of ethylene biosynthesis and ethylene action and how do they catalyze work 26 Discuss five different physiological responses regulated by ethylene 27 Discuss the interaction of auxin and ethylene during leaf abscission 28 What is the name of the pathway that produces Abscisic Acid Which pigments act as intermediates in the pathway 29 Does the level of Abscisic in plant tissues fluctuate or remain constant under changing environmental conditions Discuss the effect of water stress on ABA levels 30 How do changes in the pH of the xylem sap regulate the uptake of Abscisic Acid in leaf mesophyll cells How would this help the leaf to survive under water stress conditions 31 What is the role of Abscisic Acid during embryogenesis 32 Discuss various types of seed dormancy What three environmental factors can often affect a release from seed dormancy 33 What is the evidence that the ABA GA ratio controls certain types of seed dormancy 34 Discuss the participation of ABA receptors various second messengers changes in the membrane potential opening and closing of ion channels the vacuole and the plasma membrane proton pump in bringing about stomatal closure in response to ABA 35 What do brassinosteroids gibberellin and abscisic acid have in common with respect to biosynthesis What is the name of the most physiologically active BR and what is its immediate 36 Discuss biochemical and regulatory mechanisms for maintaining brassinosteroid homeostasis in precursor the plant 37 Cite evidence that brassinosteroids act locally near their sites of synthesis 38 Discuss several physiological effects of brassinosteroids in plants 39 What is meant by floral evocation 40 What are the signals that can cause floral evocation 41 Compare meristem identity genes and floral organ identity genes 42 What are homeotic mutations and how did their study contribute to an understanding of the 43 Discuss the known floral homeotic genes in terms of the ABC model for the determination of floral genetic control of floral development organ identity 44 What is meant by phase change Give some examples Where in the plant does phase change occur Why are the effects of phase change more marked in trees 45 What is meant by competence and determination 46 What are circadian rhythms and why are they important to flowering 47 Which wavelengths and pigments are responsible for light entrainment of circadian rhythms in plants 48 What is photoperiodism 49 Name and describe five categories of photoperiodic plants and give an example of each 50 What part of the plant perceives the photoperiodic stimulus 51 Which is more important in photoperiodism day length or night length How has the use of night breaks helped to answer this question 52 What is meant by a circadian oscillator and what is the evidence that it plays an important role 53 Which pigment is the primary photoreceptor in photoperiodism and how has this been determined in photoperiodism experimentally 54 What is vernalization and where is the vernalization signal perceived in the plant 55 Discuss how Arabidopsis was used to help better understand vernalization 56 Why does the phenomenon of photoperiodism imply the long distance transport of the floral stimulus to the shoot apex In what tissue does this occur 57