Plants Essay

1422 Words Sep 9th, 2012 6 Pages
Plants
General Characteristics: * Multicellular, primarily terrestrial eukaryotes with well developed tissues * Autotrophic by photosynthesis * Chlorophyl a and b , carotenoids etc. * Store starch in chloroplast * Cell wall – cellulose * Protect the embryo from drying out by providing it with water and nutrients within the female reproductive structure * Alternation of generation’s life cycle ( sporophyte and gametophyte phase)

Main Division:
1. Non Vascular * Lack vascular tissues * No true roots, stems and leaves * Rootlike, stemlike, and leaflike structures * Usually small * Found in moist habitat * Example: hornwort, liverwort, mosses

2. Vascular * Seedless *
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Taproot system * Characteristic of dicotyledonous plants * The primary root continous to grow and send out lateral smaller roots
2. Fibrous or Diffuse system * Characteristic of monocotyledonous plants * The primary root stops growing and numerous adventitious roots grow and develop from the base of the stem and takes the place of the primary root

Zone of Cell Differentiation * Process of differentiation completed * Located 10 to 50 mm behind the root tip * Composed of non-elongated mature cells * Presence of many ephemeral root hairs

Zone of Cell Elongation * Located 4 to 15 mm behind the root tip * Composed of long vacuolated cells * Process of differentiation starts

Zone of Cell Division * Dome shaped apical meristem * Located 0.5 to 1.5 mm behind the root tip * Divides every 12 to 36 hours * produces almost 20,000 new cells per day

Root Cap * Protects the growing root tips and its meristem * senses light and pressure exerted by soil particles * secrete mucigel, that aids in protection, lubrication, water and nutrient absorption of the roots

Epidermis * Covers all the root except the root cap * Usually one

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