LIFE 103 1st Edition Lecture 15 Outline of Last Lecture I. Solute Transport across Cell MembranesI. Active II. Passive II. Diffusion of water III. Plant water factsIV. Major pathways of transport I. ApoplasticII. SymplasticIII. Transmembrane V. Soil to xylem VI. Tension-cohesion theory Outline of Current Lecture I. Ecology: the most important field of science (very brief, not on the exam) II. TranspirationIII. Stomata IV. Movement of sugarsI. Source II. Sink Current Lecture: Resource Acquisition and Transport 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.Ecology: the most important field of scienceWhy is ecology important? I. Fundamental factsII. Helps with populationsIII. Ecosystem ecology IV. Community ecology V. Ecology makes use of other fields of science Transpiration reviewI. Fig. 36.14 II. The atmospheric CO2 concentration is now 400 parts per million (has gone up 50 parts per million in our lifetime) (will be on the test) III. Where is the force generated that draws the water up the plant? Through evaporation that pulls up the water, water film advances and draws water out of the cell away from the xylem tubes to the wetting surfaces (water tension and cohesion) IV. Fig. 36.15Resource Acquisition and Transport II I. Fig. 35.18 (diagram of a leaf) II. Fig. 36.16, a guard cell I. Stoma = spaceII. Used to open and close the vacuolesIII. Turgid- openIV. CO2 goes down when the stoma closes StomataI. 95% of water loss is via stomata, though they cover only 1-2% of leaf area II. Sausage shape of guard cells maintained by microfibrils III. Open when guard cells turgid I. Turgidity set by active pumping K+ across plasma and vacuole membranes II. Mild drought stress causes guard cells to closeI. Cues to open guard cells: light, internal CO2, circadian rhythm III. Plants lose water automatically through photosynthesis, get water through aqueous reactions (probably because they started in the ocean) IV. Fig. 36.17 V. When conditions went from wet to dry suddenly, potassium would be pumped out Movement of sugarsI. Translocation: movement of sugars from one part of a plant to anotherI. Sugar source: place where sugars are produced II. Sugar sink: place where sugars are consumed or deposited II. Transported through phloemI. Composed of sieve tube elements that are connected into sieve tubesII. Phloem sap: the sugary solution that flows through phloemIII. Trip from mesophyll cell to sieve tubes can be apoplastic or symplastic route IV. Water pressure goes up when you add sugar to a cell, pushes through the plant’s
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