Biology - Chp 23-25 - Selected Plant Topics - PowerPoint


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Biology - Chp 23-25 - Selected Plant Topics - PowerPoint

  1. 1. Selected Plant Topics Chapters 23 – 25
  2. 2. Specialized Tissues in Plants 23 -1
  3. 3. Seed Plant Structure <ul><li>Three of the principal organs of seed plants are roots, stems, and leaves </li></ul>
  4. 4. Roots <ul><li>Absorb water and dissolved nutrients </li></ul><ul><li>Anchor plants in the ground </li></ul><ul><li>Hold soil into place and prevent erosion </li></ul>
  5. 8. Stems <ul><li>Support above ground parts of plant </li></ul><ul><li>Transports nutrients </li></ul>
  6. 9. Leaves <ul><li>Main photosynthetic systems </li></ul><ul><li>Let in oxygen and carbon dioxide </li></ul>
  7. 10. Vascular Tissue <ul><li>Forms a transport system that moves water and nutrients throughout the plant </li></ul>
  8. 11. Types of vascular tissue <ul><li>Xylem – brings water and nutrients up from the roots </li></ul><ul><li>Phloem – brings food down from the leaves </li></ul>
  9. 15. Leaf Structures and Functions <ul><li>Mesophyll – where photosynthesis happens </li></ul><ul><li>Palisade mesophyll – closely packed, lots of chloroplasts </li></ul><ul><li>Spongy mesophyll – loose tissue with many airspaces </li></ul>
  10. 17. <ul><li>Stomata – pore-like openings in the underside of the leaf </li></ul><ul><li>Allow CO 2 and O 2 to diffuse in and out of the leaf </li></ul>
  11. 18. Guard Cells <ul><li>Control the opening and closing of the stomata by responding to changes in water pressure </li></ul>
  12. 20. Transpiration <ul><li>The loss of water through its leaves </li></ul>
  13. 22. Gas Exchange <ul><li>If stomata were kept open all the time, water loss due to transpiration would so great that few plants would be able to take in enough water to survive. </li></ul><ul><li>Plants keep their stomata open just enough to allow photosynthesis to take place but not so much that they lose too much water. </li></ul><ul><li>The stomata open and close in response to changes in water pressure in the guard cells </li></ul>
  14. 23. <ul><li>When pressure is high – stomata open </li></ul><ul><li>When pressure is low – stomata close </li></ul><ul><li>Q: What time of day do you think stomata are open and why? </li></ul><ul><li>A: Daytime, cause that’s when photosynthesis happens </li></ul>
  15. 24. 24 – 1 Reproduction with Cones and Flowers
  16. 25. Life Cycle of Gymnosperms <ul><li>Reproduction in gymnosperms takes place in cones </li></ul><ul><li>Male cones produce – pollen grains </li></ul><ul><li>Female cones produce – ovules </li></ul>
  17. 26. Structure of Flowers <ul><li>Flowers are reproductive organs that are composed of 4 kinds of specialized leaves </li></ul>
  18. 28. Sepals <ul><li>Enclose the bud before it opens, leaf-like </li></ul>
  19. 29. Petals <ul><li>Brightly colored, attract insects to flower </li></ul>
  20. 30. Stamen <ul><li>Male reproductive structure of flower, made of 2 parts </li></ul><ul><li>Filament – long, thin, stalk that supports the anther </li></ul><ul><li>Anther – makes pollen grains </li></ul>Anther Filament Anther + Filament = Stamen
  21. 32. Pistil <ul><li>Female reproductive structure, made of 3 parts </li></ul>
  22. 33. Stigma <ul><li>where pollen grains land, sticky </li></ul>
  23. 34. Style <ul><li>Connects stigma to ovary </li></ul>Style
  24. 35. Ovary <ul><li>swollen base of the pistil where ovules are formed </li></ul>Ovary
  25. 36. Pollination <ul><li>Most gymnosperms and some angiosperms are wind pollinated, whereas most angiosperms are pollinated by animals </li></ul><ul><li>Insect pollination is beneficial to insects and other animals because it provides them with food </li></ul><ul><li>Plants also benefit because this method of pollination is more efficient </li></ul>
  26. 37. Q: What kind of symbiotic relationship is this? <ul><li>A: Mutualism </li></ul>
  27. 38. 25 – 1 Hormones and Plant Growth <ul><li>In plants, the division, maturation, and development of cells are controlled by a group of chemicals called hormones </li></ul>
  28. 39. Hormones <ul><li>A substance that is produced in one part of the organism and affects another part of the same organism </li></ul>
  29. 40. Target Cell <ul><li>The portion of an organism affected by a particular hormone </li></ul>
  30. 41. Auxins <ul><li>Discovered by Charles Darwin and his son </li></ul><ul><li>They were trying to explain phototropism </li></ul>
  31. 42. Phototropism <ul><li>The tendency for plants to grow toward light </li></ul>
  32. 44. <ul><li>Auxins are produced in the apical meristem and are transported downward into the rest of the plant </li></ul><ul><li>They stimulate cell elongation </li></ul>
  33. 46. Gravitropism <ul><li>The response of a plant to gravity </li></ul>
  34. 47. Auxin Like Weed Killers <ul><li>High concentrations of auxins can inhibit growth, so scientists have produced many auxin like compounds to be used as herbicide </li></ul><ul><li>Ex.) Agent Orange </li></ul>
  35. 49. Cytokins <ul><li>Plant hormones that stimulate cell division , the growth of lateral buds and cause dormant seeds to sprout </li></ul><ul><li>Cytokins often produce effects opposite to those of auxins </li></ul>
  36. 50. Gibberellins <ul><li>Promote growth, particularly in stems and fruits </li></ul>
  37. 51. Ethylene <ul><li>Stimulate fruits to ripen </li></ul>
  38. 52. 25 – 2 Plant Responses
  39. 53. tropisms <ul><li>The response of plants to external stimuli </li></ul><ul><li>Ex.) gravitropism and photoperiodism </li></ul>
  40. 54. Thigmotropism <ul><li>Growth in response to touch </li></ul>
  41. 55. Rapid Responses <ul><li>Some plant responses do not involve growth, they are so rapid it would be a mistake to call them tropisms </li></ul><ul><li>Ex.) sensitive plant, venus fly trap </li></ul>
  42. 56. Sensitive Plant
  43. 57. Venus Fly trap
  44. 58. Photoperiodism <ul><li>The way a plant responds to periods of light and darkness </li></ul><ul><li>Short day plants – flower when days are short </li></ul><ul><li>Long day plants – flower when days are long </li></ul><ul><li>Photoperiodism in plants is responsible for the timing of seasonal activities of plants </li></ul>
  45. 59. Dormancy <ul><li>The period during which an organism’s growth and activity decrease or stop </li></ul><ul><li>As cold weather approaches deciduous plants turn off photosynthetic pathways, transport materials from leaves to roots, and seal leaves from the rest of the plant </li></ul>