xylem parenchyma cell collencyma cell straited muscle

xylem parenchyma cell collencyma cell straited muscle

(i) Xylem

  • Made up of vessels and tracheid
  • Consist of dead cells
  • Allows unobstructed passage of water and mineral salts
  • Has pits which permits horizontal transport
  • Narrow lumen to improve capillarity
  • Tapering ends overlap, giving additional mechanical strength
  • Long and tubular vessels, good conducting structures
  • Mark points annotated diagram

(ii) Parenchyma

  • Made up of living cells involved in food storage
  • Has a large sap vacuole, gives turgidity for support
  • Irregular in shape as packing tissue
  • Has thin cellular cell wall, pathway for water and mineral ions
  • Elongated and flattened cell offer protection from desiccation and infection
  • Plasmodesmata between adjacent cells, allow lateral transport between cells (1 x 5 = 5 marks)

(iii) Collenchyma

  • Made up of living cells; covering outer region of cortex, midrib of leaves
  • Elongated and polygonal cells
  • Tapering end; give mechanical support
  • Cell wall of cellulose; additional mechanical support (1 x 3 = 3 marks)

(iv) striated muscle

  • Numerous muscle fibres; thin myofibers; long, cylindrical with alternate light and dark bands/actin and myosin contract and relax; voluntary movement.
  • Oval nuclei at surface of each fibre; control cell activity
  • Numerous mitochondria interposed between muscle filament; presence of glycogen; provide energy for muscular action
  • Presence of vesicles triad involved in the uptake and release of Ca24 ions
  • Fibres enclosed in sarcolemma; each has several motor neurons attached to its sheath; conduction of impulse; causes contraction of fibre
  • Bundles of fibres enclosed by collagen fibres and connective tissues; from tendons at the ends of muscles attach muscles to skeletal elements (1 x 6 = 6 marks) (total = 20 marks)

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