Final answer:
Water moves across the RBC membrane by osmosis, which is dependent on the concentration of solutes relative to the surrounding environment. Without information on solute concentrations, the movement can be into or out of the cell, or bidirectional. Equal solute concentrations on both sides would mean no net water movement.
Step-by-step explanation:
In biology, particularly in discussing red blood cell (RBC) membranes, water can indeed move across the membrane. This movement is typically characterized by a process known as osmosis, which is the diffusion of water through a semi-permeable membrane. If the internal solute concentration of the RBC is higher than the outside environment, water would move into the cell to balance the concentrations. Conversely, if the solute concentration is lower inside the RBC than in the surrounding fluid, water would move out of the cell.
Assuming that other conditions are constant and focusing solely on water movement, if the concentration of solutes is equal on both sides of the RBC membrane, there would not be a net flow of water in either direction, as the osmotic pressures on both sides of the membrane would be balanced. Therefore, the answer could be:
A) Yes, into the cell - if the solute concentration outside is lower,
B) Yes, out of the cell - if the solute concentration outside is higher,
C) No, no water movement - if solute concentrations are equal,
D) Bidirectional movement - water can potentially move in both directions depending on the changing concentrations of solutes inside and outside the cell over time.