BIO 203 1st Edition Lecture 22 Outline of Last Lecture I. Remembering CatabolismII. Transferring nutrients/gasses to the bodyIII. GillsIV. Trachea and LungsV. Transport systemsVI. Open Circulatory SystemsVII. Closed Circulatory SystemsVIII. Blood VesselsOutline of Current Lecture I. How do plants capture light?II. LeavesIII. RootsIV. Properties of WaterV. How does water get to the tops of trees?VI. Vascular Tissue: PhloemCurrent Lecture I. How do plants capture light?A. Since light is a critical resource, plants try to maximize the surface area to capture as much as possible.i. Adding more cells to the body helps to a degree, but transport quickly becomes limitingii. Making stems helps with transport, but it takes leaves to make the maximization of surface area possibleiii. Since any photon that hits the ground is “wasted,” trees fill space with light-collecting surfacesII. LeavesA. Optimized for photosynthesis, fluid transport and gas exchangeB. Epidermal cells on top and bottom; secrete cuticleC. Guard cells control stomatal openingD. Palisade mesophyll cells near the top of leaves are tall, thin and tightly packedE. Spongy mesophyll cells are more unevenly shaped and surrounded by air spacesF. Vascular bundles (veins) contain xylem and phloemThese 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.G. The stomata are controlled by the guard cellsi. Guard cells are epidermal cells that open and close the stomates ii. Allow movement of carbon dioxide, oxygen, and water vaporiii. Active transport of solutes into cells results in water moving in, increasing turgor pressureiv. This OPENS the stomateIII. Roots A. Made from nested cylinders of tissue typesB. The root cap is the “helmet” of the root, cells are continually soughed off as they push through soilC. To increase surface area for absorption of nutrients, primary roots grow root hairs and lateral rootsi. Root hairs are single-cell extensions of epidermal cellsii. Lateral roots branch off of other rootsD. Almost all land plants further increase their soil-absorptive area through a mutualism with mycorrhizal fungii. Mycorrhizal fungi increase the effective surface area of the root for nutrient absorptionii. Plant provides carbon in return for this increased ability to scavenge nutrientsIV. Properties of WaterA. Osmosis is the diffusion of wateri. Selectively permeable membrane allows movement of water but not solutesii. Water always moves to equalize solute concentrationiii. “Tries to” dilute the more concentrated solutionB. Cohesion – water molecules tend to stick to one anotheri. An outcome of the polarity of water molecules and the hydrogen bonds among themC. Adhesion – water molecules tend to stick to other polar moleculesD. Cellulose is polarE. Capillarity – a consequence of adhesioni. Polar liquids are drawn up small-diameter tubesii. Adhesive force counteracts the gravitational pull on small volumes of waterV. How does water get to the tops of trees?A. Evaporation of water from leaves leads to increased solute concentration in the mesophyll cells of the leavesB. Because the concentration of ions in the leaves is increased, water from xylem moves into mesophyll cells by osmosisi. This reduces pressure in the xylem, which draws water upii. Cohesion will not allow water column to be brokeniii. Capillarity decreases the amount of pull needed to move water upwardsC. Water is pulled up the xylem tracheids and vesselsVI. Vascular Tissue: PhloemA. Phloem is a complex tissue, six types of cellsB. Function is condction of food (sugar) and many other substancesi. Hormones to signal growth, flower production or insect attackii. Amino acidsiii. Lipidsiv. Micronutrientsv. VirusesC. Cells for vertical conduction in phloem are living at maturityD. Phloem also contains ray cellsE. Transport through the phloem is driven by an osmotic pumpF. The direction of movement for the phloem sap changes through the seasonsi. Phloem sap always moves from areas of high sugar concentration to areas of low sugar concentrationii. A given tissue changes between being a source and sink over timeiii. In the warmer times of the year, the leaves are sources and the sugar flows down the phloemiv. In the early spring, the roots hydrolyze stored starch to make sugar, become sources, and the sugar flows up the phloemG. Movement of substances in phloem controlled by source-sink dynamicsi. Source – usually leaves but could be storage rootii. Sink – any growing, storing or metabolizing tissueiii. Assimilates – products moving from source to