BIOL 112 Lecture 18: BIOLOGY 18
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BIOL 112 Full Course Notes
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Protective layer = covered w/ cuticle made waxy cutin = reduces transpiration/water loss. Through evaporation - epidermis may bear trichomes = hair/scales/glands/outgrowths. Made of parenchyma cells w/ chloroplasts & large surface area for photosynthesis. Oriented & packed in at upper surface* but for dry habitat =both surface. Intercellular spaces give air chambers co2 to photosynthesizing cells & o2 to respiring cells. Specialized epidermal cells control opening & closing of stomata/pores= allow gas exchange. Xylem = water for photosynthesis phloem = transports sugar & by-products of photosynth. Bundle sheath cell surrounds vascular bundle = no vascular tissue exposed to intercellular space. No air bubbles can enter to impede movement of water & provide anaerobic environment for co2 fixation in c4 plant to other parts of plants. Water enter root through root hairs by osmosis *2 pathways for water into center of root. A- apoplast water move through cell walls & intercellular spaces from 1 to another w/out entering.
