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MACROSCALE : EVAPOTRANSPIRATION

THIS WEEKS LAB: UP AGAINST GRAVITY ! HOW DOES WATER GET TO THE TOP OF A PLANT?. MACROSCALE : EVAPOTRANSPIRATION. MICROSCALE. Stomata & guard cells !. 1 meter 39.37 inches 1 millimeter (1mm) = .001 m 1 micron ( 1 um) = .001 mm 1 nanometer (1 nm) = .001 um = 1 x 10 -9 m

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MACROSCALE : EVAPOTRANSPIRATION

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  1. THIS WEEKS LAB: UP AGAINST GRAVITY ! HOW DOES WATER GET TO THE TOP OF A PLANT? MACROSCALE: EVAPOTRANSPIRATION

  2. MICROSCALE Stomata & guard cells ! 1 meter 39.37 inches 1 millimeter (1mm) = .001 m 1 micron (1 um) = .001 mm 1 nanometer (1 nm) = .001 um = 1 x 10-9 m (1 billionth of a meter)

  3. Rooted in one spot………...no eyes…….. no ears…….. no nose……no brain…. WHAT WOULD IT BE IMPORTANT FOR PLANTS TO SENSE? LIGHT? GRAVITY? WIND/TOUCH? PATHOGENS DO PLANTS “SENSE” AND “RESPOND” TO THEIR ENVIRONMENT? HOW?

  4. ANIMALS SENSE THEIR ENVIRONMENT, AND THEY OFTEN RESPOND BY: ACTION OR MOVEMENT PLANTS SENSE THEIR ENVIRONMENT, AND THEY RESPOND BY: …..………….CHANGING THEIR GROWTH PATTERN INDETERMINATE GROWTH ! CAN PLANTS SEE? DO PLANTS SENSE LIGHT? IF SO, HOW?

  5. What do plants respond to? • Light – phototropism • Water – hydrotropism • Gravity - geotropism • Chemicals – chemitropism • Plant growth substances

  6. SUNLIGHT Is made up of different wavelengths of light. When combined, they look white to the eye. When refracted by different amounts, we see different colors which represent the different wavelengths. prism

  7. LIGHT IS COMPRISED OF MANY WAVELENGTHS Low Energy Electromagnetic spectrum EACH COLOR HAS ITS OWN WAVELENGTH High Energy

  8. PLANTS USE PARTICULAR WAVELENGHS OF LIGHT FOR PHOTOSYNTHESIS Infraredfar red CHLOROPHYLL A & B:absorb blue light (450 nm), absorb red light (680-700) reflects green light (plants appear green to the eye)

  9. PLANTS ABSORB LIGHT FOR PHOTOSYNTHESIS BUT HOW DO THEY SENSE IT?

  10. HOW CAN WE STUDY LIGHT PERCEPTION IN PLANTS? COLEOPTILE • IN MONOCOTS (GRASS, CORN) • HOLLOW, CYLINDRICAL STRUCTURE • PROTECTS PRIMARY LEAF • AS IT PUSHES THROUGH THE SOIL Coleoptiles have been used in experiments to learn about how plants sense light. primary root

  11. Darwin’s coleoptiles 1881 WHAT DO PLANTS SEE? FULL LIGHT SPECTRUM Test different wavelengths of light PHOTOTROPISM – a directed movement in response to light positive = towards light negative = away from light no response for others Blue light (450 nm) Coleoptile bends PLANTS SENSE BLUE LIGHT AND BEND TOWARD IT PHOTOTROPISM IS A RESPONSE TO BLUE LIGHT !! BLUE LIGHT IS ALSO USED IN PHOTOSYNTHESIS

  12. SIMPLE APPARATUS FOR STUDYING COLEOPTILES CAMERA COLEOPTILES GO IN HERE & LIGHT FILTERS

  13. WHAT OTHER RESPONSES DO PLANTS HAVE TO LIGHT ? SOME PLANTS PREFER FULL SUN More red light (660-700 nm) SOME PLANTS PREFER SHADE SHADE HAS MORE FAR-RED LIGHT ----WHY?

  14. MORGAN & SMITH EXPERIMENTS HOW DO PLANTS RESPOND TO FAR-RED LIGHT (indicates shade)? H0: sun and shade plants respond the same Ha: sun and shade plants respond differently Light wavelengths for photosynthesis were constant HOW WILL PLANTS RESPOND? What should we measure? Stem growth? Far red light = 720-780 nm, more in shade Red light = 600-690 nm, more in sun

  15. DATA INTERPRETATION WHAT DO THESE RESULTS TELL US ? SHADE PLANTS SUN PLANTS RESPONSE OF SHADE PLANTS ? RESPONSE OF SUN PLANTS? CONCLUSIONS? • AT LEAST SOME PLANTS CAN SENSE FAR RED LIGHT • SUN PLANTS RESPOND BY ELONGATING THEIR STEMS FASTER

  16. BEANS ARE SUN PLANTS “ESSENTIALLY GROWING OUT OF THE SHADE”

  17. How do plants know when to Flower? CAN PLANTS TELL THE LENGTH OF A DAY OR NIGHT? Spring Summer Fall Winter PHOTOPERIODISM – a response based on relative day and night length

  18. bloom in summer bloom in fall Plants appear to sense the length of the NIGHT How could we test this?

  19. HOW DO FAR-RED (735 nm) & RED LIGHT (660 nm) AFFECT FLOWERING? The Red/Far Red Switch RED has an effect FAR RED turns off effect

  20. How do RED light and FAR-RED light affect the germination of lettuce seeds? Experiment: lettuce seeds need light to germinate. Good test system ! Red light promotes germination (ON) Far-red light inhibits germination (OFF) Last wavelength determines response ON-OFF SWITCH ! Red Far-red In nature, FAR RED tells the plant it is in the SHADE!

  21. WHAT’S THE MECHANISM ? HOW DO PLANTS SENSE LIGHT? not chlorophyll ! THERE IS A LIGHT SENSING MOLECULE = PHYTOCHROME THAT CHANGES ITS SHAPE = PHOTOREVERSIBLE ! conformation FAR RED: OFF! STOP! RED: ON! GO! More Pr inhibits More Pfr stimulates

  22. Red light In sunlight, red dominates & is absorbed by the seed Weed/lettuce seeds germinate in light. red light means go

  23. Far-red light Lettuce seeds don’t germinate in the shade OFF SWITCH ! Relative amounts of: red: far-red

  24. THE HUNT FOR PHYTOCHROME BUTLER 1959 CORN STEMS ELONGATE IN FAR-RED LIGHT Scientists ISOLATED PROTEINS ONE WAS PHOTO-REVERSIBLE ! PHYTOCHROME WAS DISCOVERED !

  25. PLANTS ARE CREATURES OF LIGHT……………………… Pigment wavelength in chloroplasts Senses shade Photoperiodism NEW

  26. PHOTOTROPINS: SENSE BLUE LIGHT THEN WHAT? • SIGNAL -- BLUE LIGHT • NPH1 PROTEIN CHANGES • PO42- ADDED (PHOSPHORYLATION) (get activation) • 4. CELL RESPONSE HOW DOES THIS TRANSLATES INTO A PLANT RESPONSE? A “HOT TOPIC” OF INVESTIGATION NOW !

  27. PLANTS ARE CREATURES OF LIGHT, GRAVITY, AND FORM…….. WE WILL DISCUSS GRAVITY NEXT !

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