Humber Admissions Practice Test

What is an isotonic solution characterized by?

1. Less water concentration outside the cell

2. Equal concentrations of water inside and outside the cell

3. A higher concentration of solutes inside the cell

4. Greater water concentration outside the cell

The correct answer is: Equal concentrations of water inside and outside the cell

An isotonic solution is characterized by equal concentrations of solute and solvent, particularly water, inside and outside the cell. This means that the movement of water across the cell membrane is balanced, preventing any net gain or loss of water by the cell. As a result, cells maintain their normal shape and function effectively in an isotonic environment. In a scenario with an isotonic solution, the concentrations of substances on either side of the membrane are equal, ensuring that cells do not swell or shrink, which can occur in hypotonic or hypertonic environments respectively. This balance is crucial for maintaining homeostasis in biological systems, making both cellular and organismal functioning optimal.