What characterizes an isotonic solution?

• A. It has a higher solute concentration than the cell
• B. It has the same solute concentration as the cell
• C. It has a lower solute concentration than the cell
• D. It only exists in animal cells

Answer: (B)

An isotonic solution is characterized by having the same solute concentration as the cell's interior. In an isotonic environment, the concentration of solutes outside the cell matches that inside the cell, which means there is no net movement of water across the cell membrane due to osmosis. This balance ensures that cells maintain their shape and function properly, as there is neither swelling from excessive water intake nor shrinkage from water loss.

This characteristic is critical for cells in various biological systems, as it prevents disruptions in cellular processes that can occur if the cell becomes too hydrated or dehydrated. In contrast, a hypertonic solution (higher solute concentration) would cause the cell to lose water and shrink, while a hypotonic solution (lower solute concentration) would lead to water entering the cell, potentially causing it to swell and burst.

Furthermore, isotonic conditions can exist in both animal and plant cells, facilitating proper cellular function across different types of organisms.