phloem transport

Question

Which process explains movement of photosynthates from source to sink in phloem?

RankGuru · Accepted Answer

1. **Translocation**: The transport of food (sucrose) in the phloem.
2. **Pressure Flow Hypothesis**: Also known as the Mass Flow Hypothesis.
3. **Mechanism**: 
   - Active loading of sucrose at the **source** (leaf) creates a high solute concentration, drawing in water and increasing hydrostatic pressure.
   - At the **sink** (roots/fruits), sucrose is unloaded, water leaves the phloem, and pressure drops.
4. **Flow**: Sap moves in **bulk** from the high-pressure source to the low-pressure sink.
5. **Others**: Transpiration pull and cohesion-tension apply to **xylem** water transport, not phloem.

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phloem transport

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