translocation

translocation

movement of assimilates (sucrose) from sources to sonks

Assimilates definition

molecules which are a product of photosynthesis e.g sucrose

1) active process

the movement of sucrose formed in the source to the companion cells is an active process.

• companion cells packed with mitochondria so ATP can be produced.

2) water potential

as theres now a high sucrose conc in the sieve tubes, this lowers water potential causing water to move in by osmosis.

Causes phloem sap to move down.

3) bottom end of sieve tubes

sucrose moves into the sink and this increases water potential causing water to move back into xylem.

4) sucrose at sink

either used as glucose for respiration or starch as storage