Water transport in multicellular plants

• Into the plant

  Root hair cells - Where water is taken in:

  • Microscopic - Penetrate through soil
  • Hair - Large SA:V ratio, Large amount. Thin surface layer - Quick diffusion
  • Concentration of solutes in cytoplasm - Maintain WP gradient
• Movement of water across the root

  1. Symplast
  2. Apoplast
  3. Into the xylem
• The symplast pathway

  1. Water moves into the symplast - Continuous cytoplasm connected through plasmodesmata - Via osmosis
  2. Osmosis occurs because next cell high have lower WP than root cell
  3. Continues until xylem
• The apoplast pathway

  Apoplast - Cells walls and intracellular spaces

  1. More water move into xylem - More pulled through apoplast due to cohesion
  2. Creates tension
  3. Continuous flow through cell wall
• Movement of water into the xylem

  1. From root - Apoplast and simplest pathways - Endodermis - Layer of cells surrounding vascular tissue
  2. Casparian strip - Water forced into cytoplasm - Join symplast pathway
  3. WP of xylem lower than endodermal - Increased rate of water moving into xylem by osmosis
  4. Inside vascular bundle - Back to apoplast pathway
  5. Creates root pressure - Water pushed up xylem