I have seen on many other diagrams and other exam questions that the H+ ions are actively transported into the space between companion cell and sieve tubes, not the source cell and companion cell as you have it.
4:27 I don't fully get the diagram. I get the process with the protons but I don't get the cell(?) in between the sugar-producing cell and the companion cell.
Great question - it represents the intercellular space between cells but the key bit you need to know for AQA is about the co-transport of sucrose and the fact it requires proteins to get across cell membranes as it is too large to diffuse directly through the phospholipids UNLESS it moves through plasmodesmata which are pores between plants cells.
How are you finding the co-transport of sucrose? 🌱
I have seen on many other diagrams and other exam questions that the H+ ions are actively transported into the space between companion cell and sieve tubes, not the source cell and companion cell as you have it.
4:27
I don't fully get the diagram. I get the process with the protons but I don't get the cell(?) in between the sugar-producing cell and the companion cell.
Great question - it represents the intercellular space between cells but the key bit you need to know for AQA is about the co-transport of sucrose and the fact it requires proteins to get across cell membranes as it is too large to diffuse directly through the phospholipids UNLESS it moves through plasmodesmata which are pores between plants cells.