Translocation

The soluble products of photosynthesis are sugars and amino acids
These are transported around the plant in the phloem
- Sugars are transported in the form of sucrose
The transport of sucrose and amino acids in the phloem, from regions of production to regions of storage or use, is known as translocation
Translocation involves the transport of dissolved substances from a source to a sink inside a plant
- A source is the part of a plant that supplies sucrose and amino acids
- A sink is where sucrose and amino acids will be used or stored
Transport in the phloem occurs in different directions depending on the stage of development or the time of year

Region	Definition	Examples
Source	The part of a plant that supplies sucrose and amino acids	A photosynthesising leaf during summer will produce sugars which can be transported to other parts of the plant
		A storage organ in the roots, e.g. a potato tuber, during early spring will break down starch to produce sugars; this will fuel the growth of new leaves
Sink	The part of a plant that uses or stores sucrose and amino acids	A leaf bud during early spring will not yet be photosynthesising, so will need a supply of sugars from a storage organ
		A storage organ in the roots during the summer; leaves will produce more sugars than they need at this time of year, so excess sugars can be stored

Translocation (Cambridge O Level Biology)