BIOl 152 1st Edition Lecture 12 Outline of Last Lecture I Important Eukaryotic clades II Multi cellularity III Cell communication and differentiation Outline of Current Lecture I Plant tissue II Leaf function III Stomata IV Vascular tissue V Substance Transport VI Transfer of Xylem Sap VII Sugar Transport system Current Lecture I Plant tissue Plants consist of three main tissues the dermal tissue the ground tissue and the vascular tissue The dermal tissue is composed of the epidermis in leaves and periderm in the stem and roots and provides protection for the plant The ground tissue is composed of parenchyma which synthesizes and stores carbohydrates the main function of the ground tissue is to provide the plant with support The vascular tissue is composed of a xylem and phloem and transports nutrients and water throughout the plant II Leaf Function The main function of leaves is to photosynthesize carbon dioxide and water to produce oxygen and glucose into the atmosphere III Stomata Stomata are channels that allow for the diffusion of carbon dioxide If the guard cells uptake solute water is drawn in and stomata open If the guard cell releases solute water flows out and stomata close These notes represent a detailed interpretation of the professor s lecture GradeBuddy is best used as a supplement to your own notes not as a substitute IV Vascular Tissue Vascular Tissue is composed of two mechanisms the xylem and the phloem The xylem is composed of vessel elements and functions to transport water throughout the plant The phloem contains sieve elements and companion cells that help the phloem transport carbohydrates throughout the cell V Substance Transport Diffusion plays an important role in transport of minerals and water across short distances throughout the plant Bulk flow moves fluid in response to a pressure gradient and is more effective across large distances VI Transport of Xylem Sap Xylem transports water throughout the plant it does so by two mechanisms the root pressure and the cohesion tension mechanism The root pressure is most efficient in short distances and occurs when solutes are transported because of a positive pressure pushing the solutes upward The cohesion tension mechanism occurs when transpiration the evaporation of water causes a pull negative pressure and the cohesion between water molecules and adhesions between the water molecules and the walls of the xylem overcome the downward force of gravity VII Sugar Transport Mechanism A proton pump acts as a form of active transport that allows for the transport of sugars throughout the plant and also allows for the recycling of water through osmosis
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