Biology · CELL THE UNIT OF LIFE

Which of the following physiological statements regarding plant vacuoles and tonoplast transport is correct?

1. A
   The tonoplast is a freely permeable double-membrane that allows passive equilibration of ions between cell sap and cytoplasm.
2. B
   The tonoplast facilitates active transport of ions against concentration gradients into the vacuole, maintaining a significantly higher solute concentration in the vacuole than in the cytoplasm.
3. C
   Plant vacuoles occupy at most 10 to 20 percent of cell volume and lack hydraulic or osmotic functions.
4. D
   Contractile vacuoles in Amoeba are primarily formed by engulfment of food particles for hydrolytic enzyme release.