Translocation and transpiration

What is translocation?

The movement of sugars (produced during photosynthesis) from sources to sinks in a plant.

What direction does translocation usually occur, and what are examples of the source and sink?

Photosynthesizing leaves (source) to growing roots, developing fruits, or storage organs (sinks).

What substances are transported during translocation?

Sugars (mainly sucrose), water, minerals, amino acids, and hormones.

How does translocation occur (what is the mechanism)?

The pressure flow hypothesis. Sugars are actively transported into sieve tubes, increasing solute concentration and thus water potential. Water enters the sieve tubes via osmosis, increasing pressure. This pressure drives the sap along the sieve tube.