Rhs year 1 week 4 2011

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Rhs year 1 week 4 2011

  1. 1. RHS Level 2 Certificate Year 1 Week 4 Parts of the Plant Roots
  2. 2. Learning objectives <ul><li>1.2 Parts of the plant – an overview </li></ul><ul><li>1.2.1 State the parts of a typical seed bearing plant and their respective purposes. </li></ul><ul><li>1.3 Roots.(1) </li></ul><ul><li>1.3.1 Describe how the root system develops from the radicle. </li></ul><ul><li>1.3.2 Define the meaning of ‘primary’, ‘secondary’, ‘tap’, ‘lateral’, ‘fibrous’, and ‘adventitious’ roots. </li></ul><ul><li>1.3.3 Describe the external structure of the root tip and the role of the root cap and root hairs. </li></ul><ul><li>1.3.4 Describe how the root is adapted in order to perform specific functions. </li></ul><ul><li>1.3.5 Root fungi - symbiosis </li></ul><ul><li>1.3.6 Describe transverse sections of the young dicotyledon root; these should include the location of the following: epidermis, cortex, xylem, phloem, pith, cambium, vascular bundles, endodermis, pericycle, cuticle . </li></ul>
  3. 3. Parts of a seed bearing plant <ul><li>Review the parts of a plant </li></ul><ul><li>Introduction to their function </li></ul><ul><li>We will look at each in turn over the next few weeks – to understand how to grow plants effectively it is important to know how they work. </li></ul>
  4. 5. Roots <ul><li>What do roots do? </li></ul><ul><ul><li>Provide support and anchorage for most plants (not floating aquatics!) </li></ul></ul><ul><ul><li>Absorb water and nutrients from the soil (by osmosis) </li></ul></ul><ul><ul><li>Store food to allow the plant to survive periods of dormancy – for example carrots ( Dacus carota) and parsnips (Pastinaca sativa). </li></ul></ul>
  5. 6. Root structure
  6. 7. Types of Root <ul><li>Primary root </li></ul><ul><li>Secondary root </li></ul><ul><li>Tap root </li></ul><ul><li>Fibrous root </li></ul><ul><li>Lateral root </li></ul><ul><li>Adventitious roots </li></ul>
  7. 8. Parts of the Root <ul><li>Radicle – first root on germination </li></ul><ul><li>Root cap – protective, disposable cells covering root tip </li></ul><ul><li>Root hairs – adapted epidermis cells, absorb water and nutrients </li></ul><ul><li>Cortex – packing cells, protect other tissues and store carbohydrates </li></ul><ul><li>Pericycle – meristem, produces branching roots and thickening growth </li></ul>
  8. 9. Parts of the root <ul><li>Root tip – root apical meristem </li></ul><ul><li>Epidermis – ‘skin’ or bark of the root </li></ul><ul><li>Endodermis – layer of cells outside the pericycle that control entry and exit of water and dissolved nutrients </li></ul><ul><li>Xylem – carries water and dissolved nutrients from the roots to the tip of the shoots </li></ul><ul><li>Phloem – carries dissolved sugars and carbohydrates etc from the leaves to where they are needed. </li></ul>
  9. 10. Parts of the root – cross section
  10. 11. Parts of the Root <ul><li>Root cap </li></ul><ul><li>Root tip </li></ul><ul><li>Root hairs </li></ul>
  11. 12. Root development <ul><li>Radicle (first root produced at germination) – rapid cell division at root apex meristem, production of root hairs and subsequently branching root development from the pericycle (lateral meristem of the root). </li></ul><ul><li>Root branches in turn grow, produce root hairs and further branches. </li></ul>
  12. 13. Root adaptations – adventitious roots Adventitious roots – develop from leaf nodes or from damage to the stem. Here adventitious roots on a Swiss Cheese Plant ( Monstera deliciosa ) enable the plant to climb
  13. 14. Root adaptations – food storage <ul><li>Adapted cortex (parenchyma) cells store carbohydrates. Carrots ( Daucus carota) are biennials; food made in the first year is stored for use in the second when the flowers and seed are produced. </li></ul>
  14. 15. Root adaptations – very wet and very dry. Which is which?
  15. 16. Symbiosis – working together. <ul><li>Nitrogen fixing – bacteria that live in nodules on the roots of legumes (peas, beans, some trees) convert nitrogen gas into compounds that plants can use. </li></ul><ul><li>Mycorrhizal fungi – connect to roots (particularly trees) and take carbohydrate and water and give nutrients, especially potassium. </li></ul>
  16. 17. Learning outcomes -review <ul><li>1.2 Parts of the plant – an overview </li></ul><ul><li>1.2.1 State the parts of a typical seed bearing plant and their respective purposes. </li></ul><ul><li>1.3 Roots.(1) </li></ul><ul><li>1.3.1 Describe how the root system develops from the radicle. </li></ul><ul><li>1.3.2 Define the meaning of ‘primary’, ‘secondary’, ‘tap’, ‘lateral’, ‘fibrous’, and ‘adventitious’ roots. </li></ul><ul><li>1.3.3 Describe the external structure of the root tip and the role of the root cap and root hairs. </li></ul><ul><li>1.3.4 Describe how the root is adapted in order to perform specific functions. </li></ul><ul><li>1.3.5 Root fungi - symbiosis </li></ul><ul><li>1.3.6 Describe transverse sections of the young dicotyledon root; these should include the location of the following: epidermis, cortex, xylem, phloem, pith, cambium, vascular bundles, endodermis, pericycle, cuticle </li></ul>

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