Question

a cell is placed in an isotonic solution. how does the cell maintain homeostasis in this environment?
water will move across the cell membrane to the inside of the cell because the cell has a higher concentration of solute particles than the solution.
water will move across the cell membrane in both directions because the concentrations of solute particles inside and outside the cell are the same.
water will move across the cell membrane to the outside of the cell because the solution has a higher concentration of solute particles than the cell.
there is no movement of water molecules into or out of the cell because the concentrations of solute particles inside and outside the cell are the same.

Explanation:

In an isotonic solution, the solute concentration inside and outside the cell is equal. Osmosis (the movement of water across a semi - permeable membrane) occurs based on concentration gradients. Since there is no solute concentration gradient (same inside and outside), water moves in both directions across the cell membrane at an equal rate. This equal movement of water maintains the cell's internal balance (homeostasis). The first option is incorrect because in an isotonic solution, the solute concentrations are equal (not higher inside the cell). The third option is wrong as the solution does not have a higher solute concentration than the cell (it's isotonic). The fourth option is incorrect because water does move (in both directions), just that there is no net movement.

Answer:

Water will move across the cell membrane in both directions because the concentrations of solute particles inside and outside the cell are the same.