At the sink, solutes are unloaded by companion cells, making the sap hypotonic, which causes water to move out of the phloem into the xylem, maintaining a lower hydrostatic pressure at the sink and ensuring continued source-to-sink flow.
At the sink, solutes are unloaded by companion cells, making the sap hypotonic, which causes water to move out of the phloem into the xylem, maintaining a lower hydrostatic pressure at the sink and ensuring continued source-to-sink flow.
| Front | active transport of sucrose at the sink in phloem |
|---|---|
| Back | solutes unloaded by companion cells into sink (metabolised or stored), sap solution is hypotonic, water drawn out of phloem into xylem, ensures hydrostatic pressure is always lower at source |
Tags: 9_2_phloem_transport
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