lecture 17 notes biology

lecture 17 notes biology - Lecture 17 Notes Plant Growth...

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Lecture 17 Notes 738-763 Plastic Plants? -developmental plasticity: ability to alter its form in response to local environmental conditions - morphology : external form -entire species of plants may have natural selection accumulated adaptations in morphology that vary little among plants within the species -both genetic and environmental factors influence form in plants & animals but effect is greater in plants -plants vary much more within a species than animals do -angiosperms account for 90% of plant species 35.1 T HE P LANT B ODY HAS A H IERARCHY OF O RGANS , T ISSUES , AND C ELLS -plants have organs composed of different tissues - tissue : group of cells with a common function - organ : consists of several types of tissues that together carry out particular functions The Three Basic Plant Organs: Roots, Stems, & Leaves -plants must absorb water and minerals from below the ground surface and carbon dioxide and light from above the ground surface -organs form a root system and a shoot system (stems and leaves) -roots: typically nonphotosynthetic and starve unless photosynthates : sugars and other carbs produced during photosynthesis, are imported from the shoot system -the shoot system depends on the water and minerals that roots absorb from the soil -vegetable growth: production of nonreproductive leaves, stems, and roots, is only one stage of plant’s life -many plants also undergo reproductive growth (ie: angiosperms: reproductive shoots bear flowers) Roots - root : multicellular organ that anchors a vascular plant in the soil, absorbs minerals and water, and often stores carbs -most eudicots and gymnosperms have a taproot system with one main vertical root, the taproot : develops from an emybryonic root…taproot gives rise to lateral roots : also branch roots
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QuickTime. and a decompressor are needed to see this picture. -in many angiosperms, the taproot stores sugars and starches that the plant will consume during flowering and fruit production…taproots generally penetrate deeply and are adapted to deep soils -in seedless vascular plants and in most monocots, embryonic root dies and does not give rise to a main root…instead: many small roots grow from the stem, adventitious : a plant organ that grows in an unusual location, such as roots arising from stems or leaves -each small root forms its own lateral roots resulting in a fibrous root system : a mat of generally thin roots spreading out below the soil surface, with no root functioning as the main one (usually do not penetrate deeply…best adapted to shallow soils or light rainfall) -entire root system: helps anchor a plant…tip of root: absorption of water and minerals where the root hairs increase the surface area of the root…(short lived and constantly replaced, thin, tubular extension fo a root epidermal cell) -some have modified roots (some arise from roots, others are adventitious developing from stems or in leaves) -prop roots: support tall, top heavy plants, strangling aerial rootseeds germinate in
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This note was uploaded on 03/03/2010 for the course BIOG 1101 taught by Professor N/a during the Fall '10 term at Cornell.

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lecture 17 notes biology - Lecture 17 Notes Plant Growth...

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