What describes an isotonic solution?

An isotonic solution is characterized by having an equal concentration of solutes compared to the interior of the cell. This balance of solute concentration means that the movement of water in and out of the cell occurs at an equal rate, resulting in no net gain or loss of water. As a result, cells in an isotonic environment maintain their normal shape and function without experiencing excessive swelling or shrinkage.

In biological systems, it is crucial for cells to remain in an isotonic state when it comes to their surrounding fluids, especially in organs and systems that depend on cellular integrity. When isotonic conditions are met, cells can perform their functions without the added stress of osmotic pressure changes that can occur in hypertonic (higher solute concentration outside the cell) or hypotonic (lower solute concentration outside the cell) solutions.

The other options describe conditions that lead to either water entering or leaving the cell at different rates, which can disrupt cellular function and integrity.