Nutrients (and water) move into and within the root via three pathways:
- Apoplastic – The apoplast
is a continuum of interconnected cell walls and intercellular spaces,
extending as a unit into the water- filled xylem vessels.
- Symplastic – Through
plasmodesmata, which connect the plasma membranes of all living cells.
- Transcellular – Across
cell membranes, moving from cell to cell via repeated uptake and export
Nutrients are taken up into plant cells either:
Passively – No metabolic
energy is required; diffusion down a chemical gradient is the
driving force.
Actively – Metabolic energy
(ATP) is required, e.g., via proton pumps.
Two membranes must be crossed to enter the cell and the vacuole:
- The plasma membrane (beneath the cell
wall).
- The tonoplast (surrounding the vacuole).
