iPad 4:45 PM learn.unt.edu 79%-. Essential Elements What criteria are used to de
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iPad 4:45 PM learn.unt.edu 79%-. Essential Elements What criteria are used to determine whether an element is essential to a plant? 2. Essential Elements What is the difference between a micronutrient and a macronutrient? Name the macronutrients and micronutrients required by plants 3. Functions of Essential Elements What is the relationship between the mobility of a nutrient in the phloem and the age of leaves in which deficieney symptoms first appear? 4.Nitrogen and the Nitrogen Cycle Trace the pathway by which nitrogen is released from dead organic matter and converted to the form in which it is assimilated by plants. 5. Nitrogen and the Nitrogen Cycle Describe the sequence of events in which a nitrogen-fixing root nodule is formed. Describe the role of nitrogenase in the fixation of N. What poisons this process? is required for this process? 6. The Phosphorus Cycle Describe the steps in the phosphorus cycle. What are the major differences between the phosphorus cycle and the nitrogen cycle? 7. Movement of Water and Inorganie Nutrients through the Plant Body In what way is transpiration an "unavoidable evil for a plant? Describe the role of the stomata in transpiration. What factors control the opening and closing of stomata? 8. Movement of Water and Inorganic Nutrients through the Plant Body Describe the mechanism by which water moves from the soil to the top of a tree. What causes water to be under tension in the xylem? What are the roles of cohesion and adhesion in the process? 9. Absorption of Water and lons by Roots Explain the differences between the apoplastic, symplastic, and transcellular pathways for water (and mineral) movement across a root. What role do Casparian strips play in the entry of water into the vascular cylinder of the root? 10. Assimilate Transpert: Movement of Substances through the Phleem Explain the concept of source and sink in assimilate transport. Describe how a plant organ can bea source under certain conditions and a sink under others 1 Assimilate Transport: Movement of Substances through the Phloem Explain the pressure-flow hypothesis. Which parts of this mechanism are active and which passive? 12. Assimilate Transport: Movement of Substances through the Phloem Discuss the mechanisms of phloem loading and unloadingExplanation / Answer
1Q . An element is considered as an essential element to plant if,
It is required for completion of plant life cycle.
No other element can replace the role of the element.
It its metabolites or metabolic reactions mediated by the element are directly involved in certain physiological functions.
It is required by more number of plant species rather than one or two.
Q2). Micronutrients are those that are needed in low quantities for plant growth (not only for plants but it includes all the living beings). Zinc, iron, copper, manganese, nickel, boron, molybdenum and cobalt are some of the micronutrients essential for plant growth. Most of the micronutrients act as enzyme activators.
Micronutrients when present in excess and low quantities cause toxicity and impair plant growth, and yielding. Unlike macronutrients the safety index of micronutrients is less.
Macronutrients are those that are needed in high quantities. Macronutrients of plant include nitrogen, calcium, potassium, phosphorus, magnesium and sulphur.
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