Water potential

1
Water potential

• Using your knowledge from KS4 and your
  understanding of water potential write down how
  water travels into a root.
• (remember a plant cells cytoplasm contains some
  salts and sugars)
• Swap your work with your neighbour and peer
  assess

• Define water potential (Grade E)

2

• As water enters the root hair cell, this raises
  its water potential, so it is now higher (less
  negative) than that of its neighbouring cell.
  This means water passes from the root hair cell
  to the cortex cell next to it. This process is
  repeated across the root, until the water enters
  the xylem.

3
The 3 pathways for water to move through the root
of a plant
4
Pathways through the root

• 1)Symplast pathway goes through living parts of
  cells cytoplasm. The cytoplasm of neighbouring
  cells connect through plasmodesmata (small
  channels in cell walls)
• 2)Apoplast pathway goes through non-living
  parts of cells-cell wall
• 3)Vacuolar pathway similar to symplast but it
  can enter the vacuoles as well

• Define the three pathways that water can take
  through cells
• (Grade D C)

5
Water can only cross the root by the apoplast
pathway until it meets the endodermis!!!
6
Why is the endodermis and Casparian strip the
end of the apoplast pathway?

• Suberin in the Casparian strip stops water and
  mineral ions continuing along the apoplast
  pathway, so they have to enter the cytoplasm,
  through the cell membrane, taking the symplast
  pathway.

7
Transport through the root

• www.youtube.com/watch?vTWNtXw-MWtE
• Label pathways on your root hair structure
• Explain the vacuolar pathway

• Describe in terms of water potential, the
  movement of water between plant cells and plant
  cells and their environment (Grade C B)

• To predict the pathway that water will travel
  through the cells , using diagrams, (Grade B A)