RHS Level 2 Certificate <ul><li>Week 10 –  Plant Growth Regulators and Secondary Growth.  </li></ul><ul><li>Review and rev...
Learning objectives <ul><li>Describe two examples of how auxin influences plant growth. </li></ul><ul><li>Describe what is...
Plant Growth Regulators 1 <ul><li>Control the way in which plants grow.  For example that roots grow downwards and shoots ...
Plant Growth Regulators 2 <ul><li>Auxin – elongation of cells and fruit formation </li></ul><ul><li>Cytokinins - promotes ...
Auxin and tropisms <ul><li>Tropisms are growth responses to external stimuli </li></ul><ul><li>Phototropism – plants grow ...
Annual Rings <ul><li>Concentric rings of secondary xylem </li></ul><ul><li>Alternating bands of early and late wood </li><...
Woody Stem periderm (consists of cork, cork cambium, and secondary cortex) secondary phloem BARK HEARTWOOD SAPWOOD vascula...
Cell components <ul><li>Cell wall – cellulose mesh, reinforced with lignin in cells that do not remain active. </li></ul><...
Cell Organelles <ul><li>Chloroplasts – contain chlorophyll and are the site of photosynthesis </li></ul><ul><li>Mitochondr...
Plant cell - structure
Pollination and fertilization- overview 1 <ul><li>Pollination - transfer of pollen from the anther to the stigma of the fl...
Pollination and fertilization- overview 2 <ul><li>The pollen tube finds a tiny opening in the ovule and enters it  </li></...
Botanical naming conventions <ul><li>Genus and species in  italics  (underlined when handwritten).  Genus name starts with...
Learning outcomes <ul><li>Describe two examples of how auxin influences plant growth. </li></ul><ul><li>Describe what is m...
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Rhs year 1 week 10 overview 2011

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Rhs year 1 week 10 overview 2011

  1. 1. RHS Level 2 Certificate <ul><li>Week 10 – Plant Growth Regulators and Secondary Growth. </li></ul><ul><li>Review and revision of cells, pollination/fertilization and botanical names. </li></ul>
  2. 2. Learning objectives <ul><li>Describe two examples of how auxin influences plant growth. </li></ul><ul><li>Describe what is meant by the term phototropism. </li></ul><ul><li>State the basic changes that occur when woody dicotyledons undergo secondary growth/thickening. </li></ul><ul><li>State how strengthening tissue can be established in monocotyledons allowing perennial growth to occur. </li></ul><ul><li>Define the purposes of the various components of a plant cell and identify them on a diagram. </li></ul><ul><li>Define pollination </li></ul><ul><li>Describe the process of fertilization </li></ul><ul><li>Review and practice the conventions of botanical naming of plants. </li></ul>
  3. 3. Plant Growth Regulators 1 <ul><li>Control the way in which plants grow. For example that roots grow downwards and shoots upwards. </li></ul><ul><li>Chemicals produced by the plant which control the speed and location of the division of cells and the differentiation of those cells once produced </li></ul>
  4. 4. Plant Growth Regulators 2 <ul><li>Auxin – elongation of cells and fruit formation </li></ul><ul><li>Cytokinins - promotes cell division (mitosis), delays the senescence of leaves. </li></ul><ul><li>Gibberellins - cell division and elongation of stems. Promote flowering and bolting in ‘long day’ plants and seed germination. </li></ul><ul><li>Ethylene - ripening of fruit and senescence of leaves and flowers. Induces abscission of leaves in deciduous plants (the process of leaf fall). </li></ul><ul><li>Abscisic acid maintains dormancy in seeds and possibly in buds. It also is responsible for causing the closing of stomata – produced in response to ethylene(?). </li></ul>
  5. 5. Auxin and tropisms <ul><li>Tropisms are growth responses to external stimuli </li></ul><ul><li>Phototropism – plants grow toward the light </li></ul><ul><li>Geotropism – may be positive (growth towards gravitational pull) or negative (growth away) </li></ul><ul><li>Thigmatropism – growth towards touch. </li></ul><ul><li>Auxin migrates in the stem to cause cell elongation that causes the above growth responses </li></ul>
  6. 6. Annual Rings <ul><li>Concentric rings of secondary xylem </li></ul><ul><li>Alternating bands of early and late wood </li></ul><ul><li>Early wood </li></ul><ul><ul><li>Xylem cells with large diameter, thin walls </li></ul></ul><ul><li>Late wood </li></ul><ul><ul><li>Xylem cells with smaller diameter, thicker walls </li></ul></ul>
  7. 7. Woody Stem periderm (consists of cork, cork cambium, and secondary cortex) secondary phloem BARK HEARTWOOD SAPWOOD vascular cambium
  8. 8. Cell components <ul><li>Cell wall – cellulose mesh, reinforced with lignin in cells that do not remain active. </li></ul><ul><li>Cell membrane – holds the living contents of the cell. </li></ul><ul><li>Nucleus – contains chromosomes (DNA) and RNA. </li></ul><ul><li>Cytoplasm – jelly like substance that supports and sustains cell components. </li></ul><ul><li>Plasmodesmata – strands of cytoplasm that biochemically link cells together. </li></ul><ul><li>Vacuole – sac containing dilute sugars, waste products and nutrients. Maintains cell shape. </li></ul>
  9. 9. Cell Organelles <ul><li>Chloroplasts – contain chlorophyll and are the site of photosynthesis </li></ul><ul><li>Mitochondria – the site of respiration (that is the breaking down of carbohydrate to release energy - NOT breathing! ) </li></ul><ul><li>Ribosomes – manufacture proteins for use in the plant. </li></ul>
  10. 10. Plant cell - structure
  11. 11. Pollination and fertilization- overview 1 <ul><li>Pollination - transfer of pollen from the anther to the stigma of the flower </li></ul><ul><li>There are two haploid sex cells in the pollen grain. One cell from the pollen grain forms a pollen tube . The pollen tube grows down the style. </li></ul><ul><li>The second cell divides into two identical cells– one new cell becomes the tube nucleus which ‘drives’ the pollen tube. </li></ul><ul><li>The remaining cell divides again = two haploid sperm cells </li></ul>
  12. 12. Pollination and fertilization- overview 2 <ul><li>The pollen tube finds a tiny opening in the ovule and enters it </li></ul><ul><li>The two sperm cells enter the ovule- in the ovule are a diploid cell called the polar nucleus and a haploid female gamete </li></ul><ul><li>One sperm cell fuses with the diploid polar nucleus – this forms the triploid endosperm </li></ul><ul><li>The other fuses with the haploid female gamete and forms the zygote (the new plant embryo) </li></ul>
  13. 13. Botanical naming conventions <ul><li>Genus and species in italics (underlined when handwritten). Genus name starts with a capital letter, species name starts lower case. </li></ul><ul><li>Variety names are in italics </li></ul><ul><li>Cultivar names are in inverted single commas and in normal script. Not underlined when handwritten. </li></ul><ul><li>Hybrids – indicated by an X. Placed between the genus and species names in inter-specific crosses and before the genus name in inter-generic crosses. </li></ul>
  14. 14. Learning outcomes <ul><li>Describe two examples of how auxin influences plant growth. </li></ul><ul><li>Describe what is meant by the term phototropism. </li></ul><ul><li>State the basic changes that occur when woody dicotyledons undergo secondary growth/thickening. </li></ul><ul><li>State how strengthening tissue can be established in monocotyledons allowing perennial growth to occur. </li></ul><ul><li>Define the purposes of the various components of a plant cell and identify them on a diagram. </li></ul><ul><li>Define pollination </li></ul><ul><li>Describe the process of fertilization </li></ul><ul><li>Review and practice the conventions of botanical naming of plants. </li></ul>

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