BISC 101 Lecture Notes - Lecture 9: Tracheid, Parenchyma, Lignin
16 Jun 2016
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Document Summary
Vascular: carries out long-distance transport, made of xylem and phloem arranged in vascular bundles. Contains lignin in secondary walls for structure support during water transport. Tracheids: long, slender with tapering ends and contains pits for h2o passage. Stacked end-to-end w perforations between adjacent cells so allow h2o passage. Sieve-tube elements: alive but lacks nucleus, ribosomes, vacuole and cytoskeleton. Contains sieve plate between adjacent cells for sugar to pass through. Provides metabolic support for itself and the sieve-tubes. Ground: makes up bulk of plant pith inside vascular bundles and cortex ouside, responsible for ps and storage. Contains a lot of lignin to form wood/shells: single layer of cells (epidermis) that covers plant body like skin!, regulates exchanges with environment. Cuticle: secreted, decreases h2o loss from evaporation. Stoma/guard cells: regulate gas exchange (and water loss) Barrier defences: part of plant immune system, contains trichomes. Phenotypic plasticity: allows evolutionary development depending on specific environments (adaptations)
