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Exercise 5

Exercise 5. Plant Cell Types and Tissues. Tissue – group of cells that perform a specific function. 2 kinds of tissues (state of development): 1. Meristematic tissues/ meristerms - responsible for the production of new cells 2. Permanent tissues - perform specific functions.

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Exercise 5

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  1. Exercise 5 Plant Cell Types and Tissues

  2. Tissue – group of cells that perform a specific function 2 kinds of tissues (state of development): 1. Meristematic tissues/ meristerms - responsible for the production of new cells 2. Permanent tissues - perform specific functions

  3. Kinds of meristems based on their position or location: 1. Apical meristem – responsible for the increase in length of stems or roots - at tips or apices of stems and roots - with very small or no vacuole at all - very thin-walled and isodiametric Includes: • Protoderm • Ground meristem • Procambium

  4. 2. Lateral meristem 3. Intercalary meristem – at bases of young leaves and internodes - for further lengthening of stems and leaves far away from the tips of stems

  5. Kinds of Permanent Tissues: 1. Simple permanent tissues - consist only of one kind of cell a. Epidermis – outermost tissue of leaves, stems and roots of all monocots and herbaceous dicot - has a layer of cuticle made up of waxy substance called cutin to prevent excessive evaporation of water - uniseriate when young, multiseriate when old

  6. b. Parenchyma – uniformly thin-walled • Function: for food storage • Examples: cassava pith, tomato fruit pulp, Spanish flag petiole

  7. c. Collenchyma – with unevenly thickened walls - function: for strengthening & support and sometimes for storage - examples: lotus petiole, celery petiole, coleus petiole

  8. d. Sclerenchyma – with heavily thickened walls because of the presence of lignin • function: for strengthening & support • Examples: mungbean seed coat, peanut pericarp, pineapple leaf

  9. e. Cork – outermost tissue of leaves and roots of woody dicot plants - function: for protection

  10. 2. Complex Permanent Tissue 1. Phloem – conducts dissolved organic food materials • 2. Xylem – conducts water • Tracheids – without perforations • Vessel elements – with perforations

  11. Accessory cells – participate in osmotic changes involved in movements of the guard cells

  12. Open Stomata Closed Stomata

  13. Exercise 6 Absorption • Tap Root • Fibrous Root

  14. Specialized Roots *brace roots – aerial roots arising from the main stem which penetrates the ground *prop roots – aerial roots arising from the branches which penetrate the ground

  15. Exercise 7 Transport & Nutrition • Origin of the stem: from the epicotyl and partly from the hypocotyl of the embryo • Shoot – a stem with leaves • Shoot system – all the stems and leaves of a plant

  16. General Features of the Stem: 1. Node – where leaves, branches & buds arise 2. Internode – portion between 2 consecutive nodes 3. Leaf sheath - in some monocotyledons (Poaceae/ Gramineae/ grass family), a distinct petiole is lacking. Instead, the blade is supported by a flattened structure called the leaf sheath, which clasps the stem.

  17. 4. Petiole – or leaf stalk - holds the blade upright 5. Leaf scar – mark left on the stem by a fallen leaf 6. Bundle scar – cut end of vascular bundles seen within each leaf scar 7. Leaf axil – angle formed by the leaf stalk and the stem

  18. 8. Axillary bud – located at the leaf axil 9. Terminal bud – located at the tip of the stem 10. Bud scale – protective scale that covers the bud 11. Lenticels – tiny raised pores on dicot stems for gaseous exchange

  19. Modified Stems:

  20. Exer 7 Leaf • Important Terms: 1. Phyllotaxy – system of leaf arrangement on the stem: a. Alternate or spiral – only 1 leaf develops at each node b. Opposite – 2 leaves develop opposite each other at a node c. Whorled – 3 or more leaves develop equidistantly around the node

  21. 2. Blade or lamina – thin, flattened, green structure 3. Leaf stalk or petiole – holds the blade upright; to provide maximum exposure *sessile – leaf without petiole 4. Stipules – a pair of outgrowths at base of some dicotyledonous leaves *exstipulate – without stipules

  22. Petiolule – stalk of each leaflet • Stipels – outgrowths in pairs found at the base of petiolule • Rachis – continuation of the petiole

  23. 5. Nature of leaf blade • Simple leaf – blade consists of only 1 piece • Compound leaf – blade is divided into separate segments called leaflets or pinna

  24. 6. Venation – arrangement of vein of a leaf blade • Netted or reticulate venation – veins branch profusely and form a network over the blade; commonly found in dicot leaves • Parallel venation – veins do not form a network; commonly found in monocot leaves

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