translocation Flashcards
1
Q
what is the mass flow hypothesis?
A
it is the idea that the translocation of glucose within the phloem is caused by a never-ending flow of water and mineral ions between the source and sink
2
Q
what are the steps of translocation?
A
- sucrose produced in the mesophyll cells is actively transported into the sieve rube cell, water potential becomes more negative than adjacent xylem
- sucrose is unloaded at sink cell, water potential of sieve tube cell increases snd becomes less negative than adjacent xylem and cells, water enters xylem by osmosis, lowering hydrostatic pressure
- difference in hydrostatic pressure between sourceand sink causes mass flow of water, sucrose, and amino acids to move from leaves to roots as sap moves from a region of high hydrostatic pressure to low hydrostatic pressure