STPM Form 6 Biology Plant Tissues and Organs

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STPM Form 6 Chemistry Solids

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STPM Form 6 Biology Plant Tissues and Organs

  1. 1. TISSUES AND ORGANS
  2. 2. PLANT TISSUES
  3. 3. Plant tissues Meristemic Permanent Vascular tissues tissues GroundApical Lateral Intercalary Epidermal Supporting Xylem Phloem Parenchyma Epidermis Periderm Collenchyma Sclerenchyma
  4. 4. MERISTEMIC TISSUES Small Living tissues Unspecialised Dividing - Mitosis Large nuclei, Dense cytoplasm with small vacuoles Become specialized when matured Embryonic meristem do not stop dividing throughout the entire lifespan Only found in certain areas
  5. 5. TYPES OF MERISTEMIC TISSUES • Root tips • Shoot tipsApical • Primary growth – increase length • At nodes • MonocotsIntercalary • Grow quicker after being cut • Also called cambium • Secondary growth – increase diameter • Vascular cambium – secondary xylem & phloem Lateral • Cork cambium – For outer cork layer + suberin – Reduce evaporation
  6. 6. GROUND TISSUESPARENCHYMA CELLS  Living tissue  Contain cellulose, hemicellulose, pectin  Secondary cell wall absent  Permeable to water and solutes  Large vacuoles, Thin cytoplasm  Food storage - Apple  Water reserve  Support & Shape for Herbaceous plants  Large air space for Photosynthesis  Palisade mesophyll  Sponge mesophyll
  7. 7. PARENCHYMA
  8. 8. UNSPECIALISED PARENCHYMAGROUND TISSUE Fruits, Roots, Stem, Leaves In herbaceous plants Spherical & Thin-walled Large vacuole Thin primary wall, without secondary walls Turgid cells Provide support
  9. 9. SPECIALISED PARENCHYMA CELLSEpidermis Mesophyll cells Elongated and flattened  Palisade mesophyll Secrete cutin - Waxy cuticle  Compact cells with Protective barrier chloroplast  Water loss  Spongy mesophyll  Bacteria  Loose cells with fewer chloroplast Form stomata  Gaseous exchange  Transparent layer
  10. 10. SPECIALISED PARENCHYMA CELLS Endodermis  Selective barrier Between outer cortex and inner pericycle  Forming Casparian strip in the roots to prevent apoplastic movement of water (suberin) Pericycle  Secondary growth of roots Aerenchyma  Oxygen reserve  Buoyancy for Hydrophytes
  11. 11. Endodermis Epidermis
  12. 12. SUPPORTING TISSUESCollenchyma Sclerenchyma Living cells  More specialised Unevenly thickened cell  Die after maturity walls with Cellulose, Hemicellulose  Lignified secondary cell and Pectin walls Extra mechanical  Uniform thickening strength Stretching & elongation  Hard + impermeable to Elastic & Flexible water, solute and Allow growth of young gases plants / leaves
  13. 13. COLLENCHYMA – LIVING CELLS AT MATURITY
  14. 14. SCLERENCHYMA CELLS – DIE AT MATURITY
  15. 15. TYPES OF SCLERENCHYMA CELLS
  16. 16. TYPES OF SCLERENCHYMA Fibers – are long thin and fibrous like and usually occur in bundles  commercially used to make rope and flax fibers  Found together with xylem Sclereids – short and irregular in shape.  make up tough seed coats and pits  give pears its gritty texture
  17. 17. COMPLEX TISSUE – XYLEM & PHLOEM
  18. 18. XYLEM Transport water and minerals Types of Cells  Tracheids  Vessel elements  Xylem fibres (sclerenchyma) Die on maturity  Xylem parenchyma Cytoplasm disintegrate Empty cavity Lignified – Do not collapse Have pits – Allow lateral movement of water
  19. 19. XYLEMTracheids Vessel elements Longer  Shorter Smaller diameter  Larger diameter Tapered at 2 ends to  Joined end to end increase strength  Hollow tube Have pits in between  No pits in between More resistance  Have pits side-by-side with tracheids Lignified  Less resistance for water No perforated open ends  Strengtened with lignin between cells  Absent in fern and conifers Not hollow tube
  20. 20. PITS
  21. 21. TRACHEIDS
  22. 22. VESSEL ELEMENTS  Spiral / Annular thickening  High rate of elongation  Present in young plants to allow stretching during elongation  Present in proxylem  Scalariform / Reticulate / Pitted thickening  Low rate of thickening  Cannot be stretched  More lignifications  High tensile strength  Do not collapse when water flow through in high tension  Have pits for lateral movements of water
  23. 23. SECONDARY XYLEM Formed in both tracheids and vessel elements Except pit regions
  24. 24. XYLEM FIBRES & PARENCHYMA Xylem fibers – similar to sclerenchyma fibers Dead and lignified Only for support Parenchyma – Living cells As intermedularry rays for radial transport of food, water, gases and storage
  25. 25. PHLOEM Translocation of organic substances Four types of cells  Sieve tube cells  Companion cells  Phloem parenchyma  Pholem fibres
  26. 26. SIEVE TUBE CELLS & SIEVE PLATESSieve Tube Sieve Tube Elements Elongated  Mature sieve tube Living cells  Nucleus disintegrates Connected end-to-end  Cytoplasm remains Continuous cytoplasmic strands Sieve plates – perforated cell wall with sieve pores
  27. 27. CONTINUOUS CYTOPLASM Sieve tube elements Alive with thin cell wall and protoplasm Upon maturity, nucleus, ribosome and Golgi apparatus disintegrates Only have mitochondria and ER left for periphery transport
  28. 28. COMPANION CELL Only found in angiosperms Parenchyma cell Elongated Thin primary wall Metabolically active  Dense cytoplasm  Large nucleus  Mitocondria  Plastids  Vacuoles  RER Linked to sieve tube elements by Plasmodesmata
  29. 29. PHLOEM PARENCHYMA & FIBRES Parenchyma  Food storage  Form radial medullary rays in phloem Fibres  Support

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