plants

• Xylem vessels


  Structures that transport water and dissolved mineral ions from the soil within a plant
• Plant roots


  • Responsible for the uptake of water and mineral ions
  • Can have root hairs to increase the surface area for absorption of the substances
• Mineral ion uptake by root hair cells

  Occurs by diffusion or active transport depending on the mineral concentrations in the soil
• Uptake of minerals by root hair cells


  Lowers the water potential of the root hair cells
• Uptake of water


  Occurs by osmosis
• Plants


  • Must take in a constant supply of water and dissolved minerals to compensate for the continuous loss of water via transpiration in the leaves, and so that they can photosynthesise and produce proteins
• Apoplast pathway


  The series of spaces running through the cellulose cell walls, dead cells, and the hollow tubes of the xylem
• Symplast pathway


  Involves the cytoplasm and plasmodesmata, and vacuole of the cells
• Water reaches the endodermis


  The presence of the Casparian strip blocks the apoplast pathway
• Water and dissolved minerals reach the Casparian strip


  They must take the symplast pathway
• Casparian strip


  A thick, waterproof, waxy band of suberin within the cell wall that blocks the apoplast pathway
• The presence of the Casparian strip is not fully understood but it is thought that forcing water into the symplast pathway, and therefore through cell membranes, may help the plant control which mineral ions reach the xylem
• Water movement in the symplast pathway


  Slower than the apoplast pathway
• Water movement in the apoplast pathway


  More rapid than the symplast pathway