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Unformatted text preview: B I O L O G Y 12 2 3 Plant Form and Function What is a Plant? B I O L O G Y 12 2 3 Overview • Plants are photosynthetic autotrophs • Shoot system aboveground – Photosynthetic leaves, stems • Root system belowground – Nonphotosynthetic roots B I O L O G Y 12 2 3 Plant Tissues • All plant cells share certain features: – Primary cell wall around protoplast (cytoplasm) – Cellulose fibers in matrix of hemicellulose – Rigid but flexible • Some plant cells have secondary cell wall – Cellulose fibers anchored with lignin – Stronger and more rigid – Creates waterproof barrier Fig. 31.2, p. 713 Lateral bud Terminal bud Young leaf Reproductive shoot with flower Vegetative shoot Dermal tissue Leaf Seeds in fruit Withered seed leaf (cotyledon) Root hairs (not to scale) Root tip Root cap Lateral root Primary root Root system Shoot system Ground tissues Vascular tissues Node Internode Node Growth • Determinate growth common in animals • Indeterminate growth in plants – Plant grows throughout life – Meristems give rise to plant body – Plasticity of growth gives some flexibility since plants cannot move around • Plants grow by: – Increase in number of cells – Increase in size of cells Primary Growth • Apical meristems at root and shoot tips – Increases height of shoot, length of roots • Some species only have primary growth Secondary Growth • Lateral meristems at root and shoot tips – Self-perpetuating cylinder of tissue – Increases diameter of stems and roots B I O L O G Y 12 2 3 Lifespans • Annual (one growing season) – Herbaceous...
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This note was uploaded on 04/18/2010 for the course BIOLOGY 1223 taught by Professor Gardiner/lajoie during the Fall '09 term at UWO.
- Fall '09