What physiological process ensures that cells maintain their shape in hypotonic environments?

• A. Cellular respiration
• B. Osmoregulation
• C. Diffusion
• D. Active transport

Answer: (B)

Osmoregulation is the physiological process that allows cells to maintain their shape and internal balance in hypotonic environments, where the concentration of solutes outside the cell is lower than inside. In such conditions, water moves into the cell through osmosis, which can lead to swelling or even bursting if not properly regulated.

Cells manage this influx of water through various mechanisms of osmoregulation. For instance, some cells may use a contractile vacuole to expel excess water, while others may regulate solute concentrations within their cytoplasm to balance osmotic pressure. These strategies help to ensure that cells do not take in too much water, thus preventing lysis (breaking apart) and maintaining cellular integrity.

In contrast, while cellular respiration, diffusion, and active transport are important biological processes, they do not primarily address the issue of maintaining cell shape specifically under hypotonic conditions. Cellular respiration focuses on energy production, diffusion relates to the movement of molecules down their concentration gradient, and active transport involves moving substances against their concentration gradient, which is not directly tied to managing osmotic pressure.