specialisation

• Differentiation


  The process where cells become specialized
• Root hair cells


  • Increase the surface area of the root to absorb water and dissolved minerals more effectively
  • Do not contain chloroplasts
• Xylem cells


  • Have very thick walls containing lignin to provide support
  • Have no internal structures like nucleus, cytoplasm, vacuole or chloroplasts to allow easy flow of water and dissolved minerals
• Phloem cells


  • Consist of two types: phloem vessel cells with no nucleus and limited cytoplasm, and companion cells with mitochondria to provide energy to the phloem vessel cells
  • Phloem vessel cells have porous end walls called sieve plates to allow flow of dissolved sugars
• Xylem cells form long tubes that carry water and dissolved minerals from the roots to the leaves
• Phloem tubes carry dissolved sugars up and down the plant