Final answer:
Isotonic solutions have the same osmolarity as cells, preventing net water movement across cell membranes. Common examples include 0.9% NaCl and 5% glucose solutions, which are used medically to avoid cell volume changes. Isotonic sports drinks also match body fluid concentrations to aid hydration.
Step-by-step explanation:
Isotonic Solutions in Biology
Isotonic solutions are critical in biological systems as they ensure that the extracellular fluid has the same osmolarity as the cells. This balance is important as it prevents any net movement of water across the cell membrane, thereby maintaining cell shape and function. Common isotonic fluids include a 0.9% m/v NaCl solution (normal saline) and a 5% m/v glucose solution, both of which have similar osmolarity to blood. In medical settings, isotonic solutions like normal saline and lactated Ringer's solution are routinely used in intravenous therapy to match the osmotic pressure of body fluids, avoiding the adverse effects of cells shrinking or swelling.
When red blood cells are placed in an isotonic environment, they maintain their characteristic shape, unlike in a hypertonic environment where they would shrink due to crenation. Sports drinks are another example where isotonic variations are formulated to match the salt and sugar concentration of the human body for effective hydration. Understanding the properties of isotonic solutions is crucial for applied health sciences.