Final answer:
The movement of water into a cell is determined by osmosis, with water moving from an area of higher concentration to lower concentration, influenced by the relative solute concentrations in a hypotonic, hypertonic, or isotonic solution.
Step-by-step explanation:
The direction of the movement of water in a cell that gains water can be determined by the relative concentration of solutes inside and outside the cell. When a cell is placed in a solution, water moves across the cell membrane by osmosis, which is the diffusion of water molecules from an area of higher water concentration to an area of lower water concentration through a selectively permeable membrane.
If the cell is in a hypotonic solution, water will move into the cell, causing it to swell. If too much water enters, this can lead to cell lysis unless a cell wall provides counteractive pressure. Conversely, in a hypertonic solution, water will flow out of the cell, causing it to shrink. Cells maintain optimal function when they are in an isotonic solution, where solute concentration is equal inside and outside, allowing for equilibrium in water movement.