Answer:
A proton Pump, using ATP, pumps protons outside
A steady proton gradient with a higher concentration of H+ out of the cell is maintained by the proton pump.
pH decreases;
The gradient becomes sufficient.
H+ moves down electrochemical gradient into the cell; Sucrose moves into the cell.
Explanation:
A proton Pump, using the energy of ATP hydrolysis, pumps protons outside the cell.
A steady proton gradient with a higher concentration of H+ out of the cell is maintained by the proton pump.
The continues outward pumping of protons by the proton pump causes the pH of the extracellular fluid to decrease
At some point the gradient becomes sufficient, and pH reaches a steady slightly acidic level.
H+ moves down its electrochemical gradient into the cell together with Sucrose through the hydrogen ion-sucrose co-transporter.
The plasma membrane maintains homeostasis in the cell by keeping cell contents in and foreign material out, and by providing controlled avenues for the transportation of fuel, fluids and waste.
