Transport in plants

Question 1

what does translocation do? where does it take place phloem or xylem?

Answer 1

transports assimilates from source to sink in phloem

Question 2

describe the process of translocation

Answer 2

1. sucrose produced when plant (leaves) photosynthesise
2. sucrose loaded into phloem via active transport
3. hydrogen ions flow down conc gradient causing inward flow of sucrose into companion cell increasing solute concentration
4. sucrose diffused through plasmodesmata into the sieve tube elements , lowering water potential
5. causes water to enter via osmosis from the xylem vessels , increasing hydrostatic pressure
6. phloem sap moves down sieve tube elements towards sinks (mass flow)
7. at the sink, sucrose unloaded and converted into glucose for respiration