BIOL 1106 Lecture Notes - Lecture 3: Sucrose, Plant Hormone, Phloem
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BIOL 1106 Full Course Notes
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Lesson 3 transport throughout the plant body. Overview of transport: how can water move water from roots to the top of tall trees, water moves unidirectionally upwards, carbohydrates move bidirectionally in the plant. Aquaporins: once thought water moved across plasma membranes only by osmosis through the lipid bilayer, osmosis is enhanced by membrane water channels call aquaporins. Water and mineral absorption: root hairs provide surface area, surface area further increased by mycorrhizal fungi, water and minerals must move across cell layers until they reach the vascular tissues. Water and mineral absorption: water enters in the root, but moves upward to the leaves as they have the lowest water potential in the plant. Cavitation: air bubbles break tensile strength of water in tracheids, may expand and block the tracheid or vessel, damage can be minimized by anatomical adaptations, presence of alternative pathways. Conditions that promote stomatal closing: co2, temperature exceeds 30-34 celsius, unfavorable water conditions.
