Yellow Packet Notes


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Yellow Packet Notes

  1. 1. Plant Responses
  2. 2. Factors <ul><li>Plant growth depends on INTERNAL factors, such as HORMONES, and external factors such as… </li></ul><ul><ul><li>LIGHT INTENSITY </li></ul></ul><ul><ul><li>GRAVITY </li></ul></ul><ul><ul><li>TEMPERATURE </li></ul></ul><ul><ul><li>MOISTURE </li></ul></ul><ul><ul><li>LENGTH OF DAY </li></ul></ul>
  3. 3. Hormones <ul><li>Any chemical produced in one part of the body that has a target elsewhere in the body </li></ul><ul><li>Affect GROWTH, FLOWER, and FRUIT development </li></ul>
  4. 4. Hormones <ul><li>Examples </li></ul><ul><ul><li>Auxin </li></ul></ul><ul><ul><li>Gibberellins </li></ul></ul><ul><ul><li>Cytokinins </li></ul></ul><ul><ul><li>Abscisic Acid </li></ul></ul><ul><ul><li>Ethylene </li></ul></ul>
  5. 5. Hormone - Auxin <ul><li>Produced in APICAL MERISTEMS </li></ul><ul><li>Regulates growth </li></ul><ul><li>Promotes cell elongation </li></ul><ul><li>Also known as IAA (Indoleacetic acid) </li></ul>
  6. 6. Hormone - Auxin <ul><li>Tissue response depends on hormone CONCENTRATION </li></ul><ul><li>ROOT cells are more sensitive than STEM cells </li></ul>
  7. 7. Hormone - Auxin <ul><li>Causes cells on darker side of the plant to grow larger than corresponding cells on the lighter side of the plant </li></ul><ul><li>Involved in plant movement ( TROPISM ) </li></ul>
  8. 9. Hormone - Auxin <ul><li>Synthetic auxins can stimulate fruit development without fertilization ( SEEDLESS fruit) </li></ul>
  9. 10. Hormone - Gibberellins <ul><li>Produced in YOUNG tissue </li></ul><ul><li>Causes elongation of STEM cells and growth of LEAVES </li></ul><ul><li>Focus on stem growth </li></ul><ul><li>Stimulates SEED germination </li></ul>
  10. 11. Hormone – Cytokinins <ul><li>Produced in the ENTIRE plant </li></ul><ul><li>Promotes MITOSIS </li></ul><ul><li>Involved in the closure of STOMATA during dry periods </li></ul><ul><li>Promotes DELAY OF AGING </li></ul>
  11. 12. Hormones – Abscisic Acid <ul><li>Produced in LEAVES </li></ul><ul><li>Mediates the adaptation of the plant to stress </li></ul><ul><li>Promotes DORMANCY (helpful during drought season) by inhibiting growth of BUDS and germination of SEEDS </li></ul><ul><li>Promotes abscission of leaves & fruit </li></ul>
  12. 13. Hormones - Ethylene <ul><li>A GAS that promotes ripening of fruit </li></ul><ul><li>Produced in the ENTIRE plant </li></ul><ul><li>Causes RIPENING of fruit by softening cell walls and converting starches into sugar </li></ul><ul><li>Promotes SENESCENCE (causes nearby fruit to ripen) </li></ul>
  13. 14. Plant Movements <ul><li>Tropism </li></ul><ul><li>Nastic Movements </li></ul>
  14. 15. Tropism <ul><li>Growth movement towards the direction from which the stimulus strikes the plant. </li></ul><ul><li>Takes the name of the STIMULUS </li></ul><ul><li>Positive </li></ul><ul><ul><li>Growth in the direction of the stimulus </li></ul></ul><ul><li>Negative </li></ul><ul><ul><li>Growth away from the stimulus </li></ul></ul>
  15. 16. Phototropism <ul><li>Response to light </li></ul><ul><li>Stems are positively phototropic </li></ul><ul><li>Roots are negatively phototropic </li></ul>
  16. 17. Phototropism <ul><li>Caused by unequal distribution of AUXIN </li></ul><ul><ul><li>Auxin is transported away from light therefore, there is a [ HIGHER ] away from the light, which causes CELL elongation. </li></ul></ul><ul><ul><li>This “bends” the plant toward the sun. </li></ul></ul><ul><ul><li>Solar Tracking Clip </li></ul></ul>
  17. 18. More Auxin Less Auxin Animation
  18. 20. Phototropism
  19. 21. Thigmotropism <ul><li>Response to touch </li></ul><ul><li>Climbing vines </li></ul><ul><li>Wraps around a solid object </li></ul>
  20. 24. Gravitropism <ul><li>Response to gravity </li></ul><ul><li>Roots are POSITIVELY gravitropic </li></ul><ul><li>Stems are NEGATIVELY gravitropic </li></ul>
  21. 26. Chemotropism <ul><li>Response to a chemical </li></ul><ul><ul><li>Pollen tube growth toward the ovule </li></ul></ul>
  22. 27. Hydrotropism <ul><li>Response to water </li></ul><ul><ul><li>Willow tree roots are notorious from ruining underground pipelines </li></ul></ul>
  23. 29. Nastic Movements <ul><li>Movement that is independent of the direction of the stimulus </li></ul><ul><li>Movement is regulated by changes in the WATER pressure of cells </li></ul><ul><li>Animation </li></ul><ul><li>Examples </li></ul><ul><ul><li>Venus Fly Trap </li></ul></ul><ul><ul><li>Sun Dew </li></ul></ul>
  24. 33. Photoperiodism <ul><li>Response to DAY LENGTH </li></ul><ul><li>Involves a hormone called PHYTOCHROME </li></ul><ul><ul><li>Two forms </li></ul></ul><ul><ul><ul><li>Phytochrome Red (P r ) </li></ul></ul></ul><ul><ul><ul><li>Phytochrome Far Red (P fr ) </li></ul></ul></ul>
  25. 34. Photoperiodism <ul><li>Ratio of P r and P fr is thought to explain how a plant can CALCULATE THE LENGTH of the day (or night) </li></ul>
  26. 35. LONG Day Plants <ul><li>Flower when… </li></ul><ul><ul><li>Days are long </li></ul></ul><ul><ul><li>Nights are short </li></ul></ul><ul><li>Occurs during the SUMMER . </li></ul><ul><li>Examples </li></ul><ul><ul><li>Radishes, petunias, wheat </li></ul></ul>
  27. 36. SHORT Day Plants <ul><li>Flower when… </li></ul><ul><ul><li>Days are short </li></ul></ul><ul><ul><li>Nights are long </li></ul></ul><ul><li>Occurs during the SPRING & FALL </li></ul><ul><li>Examples </li></ul><ul><ul><li>Goldenrods, poinsettias, soybeans </li></ul></ul>
  28. 37. DAY-NEUTRAL Plants <ul><li>Do not have a critical period of day length </li></ul><ul><li>Flower during SPRING through FALL </li></ul><ul><li>Examples </li></ul><ul><ul><li>Dandelions, tomatoes, corn </li></ul></ul>
  29. 39. Photoperiodism of Short-Day Plant
  30. 42. Phytochrome <ul><li>Phytochrome RED (P r ) </li></ul><ul><ul><li>Converts RED wavelengths of light into FAR RED wavelengths during the day </li></ul></ul><ul><li>Phytochrome FAR RED (P fr ) </li></ul><ul><ul><li>Converts FAR RED wavelengths of light into RED wavelengths of light at night </li></ul></ul>