Bio1b Summer 2008 Plants Lecture 7Eric Harris Page 1 of 2PLANTS LECTURE 7: THE PLANT BODY II: ROOTSReading: 7th ed., 721–723, 744–746, 756–759, 763–767, 809. 8th ed., 747–749, 772–773, 789–797, 841–842. A. Rootsi) Functionii) Types of root systems: monocot vs. dicotiii) Regions – zone of division, differentiation & elongationiv) Root cap – functions, gravitropismv) Anatomyxylem, phloem, endodermis, pericycle, cortex, epidermis, root hairsvi) Lateral roots - originvii) Modifications of rootsprop, storage, buttressB. Modes of Absorptioni) Water & dissolved nutrients may move through the apoplast (in and between cell walls) or the symplast (through cells). Water & dissolved nutrients moving through the apoplast is unregulated (does not pass through selectively permeable cell membranes). One water & dissolved nutrients enter the symplast, they can move from cell to cell via plasmodesmata. ii) The casparian strip (a waxy ‘gasket’) forces water entering the vascular tissue to pass through the symplast.C. Symbionts (review) i) Nodules & Nitrogen fixation - Symbiotic association with bacteriaUpdated on 08/01/08Bio1b Summer 2008 Plants Lecture 7Eric Harris Page 2 of 2ii) Mycorrhizae (recall: ectomycorrhizae & arbuscular mycorrhizae)D. Nutrient Uptakei) Macronutrients (C H O P K N S Ca Mg)Required in relatively large amountsii) Micronutrients (Cl Fe Mn B Z Cu Ni Mo)Required in trace amounts, mainly function as cofactorsiii) Mobile vs. Immobile nutrientsiv) Nutrient deficiency in plantsSymptomsUpdated on
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