Summary PLANT TISSUES - GRADE 10 IEB LIFE SCIENCE

Plant Tissues



Meristematic Tissue
 Continuously form via mitosis.
 Unspecialised & undifferentiated.
 Occurs in growth (dark) regions of:
 Apical Meristem
 Primary Growth (length)
 Tips of: Roots & Shoots




 Lateral Meristem
 Cambium – Within the vascular bundle between the phloem &
xylem of dicotyledonous plants
 Secondary Growth
 Flowers, Branches
 Structure:
 Small
 Cubic
 Densely packed with no intercellular spaces
 Large nucleus
 Dense cytoplasm
 Vacuole absent

, Ground Tissue
Parenchyma
 Most general tissue type:
 Dead
 Thin-walled
 Large Vacuoles
 Rounded to elongated.
 Intercellular spaces present
 Aerenchyma – Filled with air & large intercellular spaces.
 Chlorenchyma – Contain chloroplasts.

Functions:
 Filling tissue
 Storage: Food & water
 Secretions: Resin, tannins (wood pigment), hormones, enzymes & nectar.
 Aerenchyma
 Large intercellular airspaces filled with air for gaseous exchange.
 Flotation/buoyancy for aquatic-plants.



Collenchyma
 Are alive, even when mature.
 Irregularly thickened walls, especially in the corners.
 Primary Cell walls thickened with cellulose at the corners.
 Intercellular spaces absent.
 Mainly found as strands in the ground tissue.

Functions:
 Provides strength & support.
 Stems, petioles & leaf veins.
 Flexible yet firm.
 Can photosynthesise if chloroplasts present.




Sclerenchyma
 Hard and even thickened (lignin) secondary cell walls.
 Cell walls are inelastic.
 No living cell contents when mature.
 Sclereids
 Different shapes.
 Commonly found in the shell of nuts.
 Gives granular structure to pears & guavas.
 Fibres