BRAINCAKEMass Flow Hypothesis
The mass flow hypothesis (proposed by Ernst Münch) explains how phloem sap moves from source to sink. Mass flow is the bulk movement of a liquid, with everything dissolved in it, down a pressure gradient.
At the source
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Key terms in this lesson
- hydrostatic pressure
- The pressure a fluid exerts on the walls of its container; in a capillary it pushes fluid out through the gaps between the endothelial cells.
- water potential
- A measure of the tendency of water molecules to move out of a solution; water moves from a higher to a lower (more negative) water potential.
More in Transport in Plants
- Factors Affecting Transpiration
- Root Pressure
- Translocation in the Phloem
- Phloem Loading
- The Symplast Pathway
- The Apoplast Pathway
- Phloem Unloading
- Pressure Flow Hypothesis
All 21 lessons in Transport in Plants · All Edexcel AS-level Biology topics