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Copyright Notice! This PowerPoint slide set is copyrighted by Ross Koning and is thereby preserved for all to use from plantphys.info for as long as that website is available. Images lacking photo credits are mine and, as long as you are engaged in non-profit educational missions, you have my permission to use my images and slides in your teaching. However, please notice that some of the images in these slides have an associated URL photo credit to provide you with the location of their original source within internet cyberspace. Those images may have separate copyright protection. If you are seeking permission for use of those images, you need to consult the original sources for such permission; they are NOT mine to give you permission. Figure 40.11 Center of meristem Figure 40.12 Gravity Cell in root tip (or shoot) Amyloplasts are pulled to bottom of cells by gravity Activated pressure receptors Auxin distribution Auxin Gravity Figure 40.13 1. Normal distribution of auxin. 2. Root tip rotated. 3. Auxin is redistributed, move to bottom. 4. Root bends. Figure 40.3a (a) Shoots bend toward full-spectrum light. Figure 40.3b (b) Shoots bend specifically toward blue light. Figure 40.5 Where is light sensed to initiate phototropism in grass seedlings? Light is sensed at the tip of a coleoptile. Light is not sensed at the tip of the coleoptile. Control: Bends toward light Tip removed: No bending Tip covered: No bending Lower portion of coleoptile covered: Bends toward light Light Light responsible for triggering phototropism is sensed at the coleoptile tip. Light (stimulus) Sensing tissue Hormonal signal 1. Cells at coleoptile tip sense light. Responding tissue 2. Hormone travels from tip down the coleoptile. 3. Cells lower in coleoptile respond to hormone. Bending results. This interpretation explains the hormone concept, but does not explain differential growth on the lighted and shaded sides of the coleoptile… Based on what you know about gravitropism, give a parsimonious (i.e. parallel) interpretation. Biology: life study of What is Life? Properties of Life Cellular Structure: the unit of life, one or many Metabolism: photosynthesis, respiration, fermentation, digestion, gas exchange, secretion, excretion, circulation--processing materials and energy Growth: cell enlargement, cell number Movement: intracellular, movement, locomotion Reproduction: avoid extinction at death Behavior: short term response to stimuli Evolution: long term adaptation Obtaining Food Autotrophs use ambient energy and carbon dioxide to make their own organic molecules. So the only matter they need to take up is minerals! Sadly they are sometimes called “plant food.” Johann Baptista van Helmont 1577-1644 Physician Scientist In 1648 experiment with Salix (willow) he tested whether the bulk of a plant comes from the soil or from some other source. His experiment was carefully documented but, because he was so far ahead of his time, his conclusion was wrong. Interestingly, however, his results suggest that plants do use soil minerals for growth. In the light of knowledge of carbon dioxide gas, the project shows that the plant grows mostly from air. http://upload.wikimedia.org/wikipedia/commons/1/1d/Jan_Baptist_van_Helmont.jpg Because the role of air was not understood yet, van Helmont concluded that the weight increase was due only to water…WRONG. sunlight 169 lbs + 3 oz sapling H2O 5 lbs branch 200 lbs soil Copyright © 2008 Pearson Education Inc., publishing as Pearson Addison-Wesley Adapted from: Figure 39.1 Page 776 Even if the plant is 90% water, the 10% dry weight (16.9 lbs) would have to come from somewhere. 200 lbs - 2 oz soil Because the role of air was not understood yet, van Helmont concluded that the weight increase was due only to water…WRONG. sunlight CO2 H2O O2 169 lbs + 3 oz sapling 5 lbs branch CH2O 200 lbs soil Copyright © 2008 Pearson Education Inc., publishing as Pearson Addison-Wesley Adapted from: Figure 39.1 Page 776 Even if the plant is 90% water, the 10% dry weight (16.9 lbs) would have to come from somewhere. Could it be minerals from the soil? 200 lbs - 2 oz soil This decrease could be sample error, or minerals taken from the soil by the growing plant. Autotrophic Organisms Typically autotrophs carry out photosynthesis: light CO2 + H2O O2 + CH2O chlorophyll As you can see, the plant needs NO food. But the enzymes and ion transporters for photosynthesis require metal cofactors: The essential macroelements are: CHOPKNS CaFe Mg The essential microelements are: CuMn CoZn Si Mo B Al Cl “C. Hopkins Café Mmm, good!” “CoMe on, Cousin, See Mike over By Al and Cleo” Essential “macroelements” for plants Element Requirement Functions N (nitrogen) 21 g/m3 P (phosphorus) 5 Nucleic acids, phospholipids, ATP, enzyme cofactor K (potassium) 16 Ion balance, enzyme cofactor S (sulfur) 10 Cysteine and methionine, vitamins Mg (magnesium) 7 Chlorophyll cofactor, enzyme cofactor Ca (calcium) 7 Membrane permeability, pectin glue, enzyme cofactor Fe (iron) 0.3 Cytochrome cofactor, enzyme cofactor Amino acids, nitrogenous bases, vitamins “Plant Food” has N-P-K analysis = %N-%P-%K Essential “microelements” for plants Element Requirement Functions Mn (manganese) 0.04 g/m3 B (boron) 0.008 Enzyme cofactor, pollen tube attraction Cl (chlorine) 0.008 Ion balance, cofactor Zn (zinc) trace Enzyme cofactor, hormone synthesis, DNA binding protein cofactor Cu (copper) trace Enzyme cofactor (polyphenol oxidase), plastocyanin cofactor Mo (molybdenum) trace Cofactor for nitrate reductase, nitrogen reductase (N2 fixation) Ni (nickel) trace Cofactor for urease (for uptake of organic N source) Enzyme cofactor Macroelements Microelements http://www.elementsdatabase.com/Images/periodic_table.gif ©1996 Norton Presentation Maker, W. W. Norton & Company Radish seedlings have roots with long root hairs that increase the surface area for water and mineral uptake