Study Guide for Test 2

Study Guide for Test 2 - Study Guide for Test 2 The Root:...

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Study Guide for Test 2 The Root: Structure and Development It is the first Structure to emerge from the seed Functions of Roots o Anchorage o Absorption o Storage Ex. carrot, sugar beet, and sweet potato Food manufactured above ground in photosynthesizing portions of the plant and move through the phloem to the storage tissues of the root o Used to produce flowers, fruits, and seeds o Conduction Hormones are synthesized in the meristematic regions of the roots are transported upward in the xylem to the aerial parts o Cytokinins and Gibberellins Stimulate growth and development Synthesize a wide variety of secondary metabolites o Ex. Nicotine Root Systems o Primary Root (taproot in monocots) Grows directly downward o Lateral Roots Branch off the Primary root The older lateral roots are found nearer the base of the root o Taproot system One strongly developed primary root and lateral branches Penetrate deeper into the soil o Fibrous Root systems The main root system of the plant develops from roots that arise from the stem Primary root is short-lived No one root is more prominent than the others Shallowness and the tenacity with which they cling to soil particles make them especially well suited as ground cover for soil erosion prevention o Extent of a root system to which it penetrates the soil and the distance it spreads laterally Dependent on moisture, temperature, and composition of the soil Feeder roots fine roots actively engaged in the uptake of water in minerals) Occurs in the uppermost meter of soil Origin and Growth of Primary Tissues
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o Rootcap Is a thimble like mass of living parenchyma cells that protects the apical meristem and aids the root in its penetration of the soil As the root grows longer, the rootcap is pushed forward, the cells on the periphery of the rootcap are sloughed. The sloughed cells and the growing root tip are covered by Mucigel o Mucigel lubricates the root during its passage through the soil It is highly hydrated polysaccharide As rootcap cells are sloughed off, new ones are added by the apical meristem Plays a key role in conrolling the response of the root to gravity (gravitropism) Columella, located in the center of the rootcap is the site of perception of gravity. A type of Amyloplast o Apical Oragnization in Roots Region of Cell Division Apical meristem o Located after the Promeristem o Gives rise to three primary meristmes Protoderm Epidermis Ground Meristem Cortex o Contains numerous intercellular spaces Inner boundary contains the Casparian strips on their anticlinal walls Prochambium Vascular cylinder o The primary xylem occupies the center of the vascular cylinder Has radiating ridges that alternate with strands of primary phlom Lateral roots originate from the pericycle Promeristem o Before the Apical Meristem
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o The most distal (closest to the root tip) and least
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This note was uploaded on 04/07/2008 for the course MUSIC 101 taught by Professor Foy during the Spring '08 term at DePauw.

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Study Guide for Test 2 - Study Guide for Test 2 The Root:...

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