What does isotonic mean in terms of solute and solvent concentration?

Isotonic refers to a state where two solutions have the same concentration of solute particles. When a solution is described as isotonic, it indicates that the concentration of solute is equal on both sides of a semipermeable membrane, resulting in no net movement of water across the membrane. This balance is crucial in biological systems to maintain cell shape and function, as cells in isotonic solutions neither swell nor shrivel.

The concept of isotonic conditions is important for understanding processes such as osmosis, wherein water moves from areas of low solute concentration to areas of high solute concentration in order to achieve equilibrium. Therefore, the correct interpretation of isotonic is that there is an equal concentration of solute in comparison to other solutions.