The diagram shows the active loading of sucrose into a phloem companion cell from the apoplast (cell wall space).
Based on this mechanism, what is the relative state of the apoplast compared to the cytoplasm of the companion cell, and how does sucrose enter the companion cell?
The apoplast has a higher pH than the cytoplasm; sucrose enters the companion cell via active transport directly coupled to ATP hydrolysis.
The apoplast has a lower pH than the cytoplasm; sucrose enters the companion cell via co-transport down the proton electrochemical gradient.
The apoplast has a lower pH than the cytoplasm; sucrose enters the companion cell via simple diffusion through open channel proteins.
The apoplast has a higher pH than the cytoplasm; sucrose enters the companion cell via co-transport down the sucrose concentration gradient.