Final answer:
A red blood cell in a 10% salt solution will shrivel due to the hypertonic environment causing water to leave the cell. If placed in a pure water (hypotonic) environment, the cell would swell and burst. Optimal function is maintained in an isotonic solution, where solute concentrations are equal.
Step-by-step explanation:
When a red blood cell, which normally contains 5% salt, is placed into a 10% salt solution, it is subjected to a hypertonic environment. Due to the cell's membrane being permeable to water but not to salt, water will diffuse out of the cell and into the surrounding solution in an attempt to equalize the osmotic pressure. This outflow of water will cause the red blood cell to shrivel and become deformed (a process known as crenation). In this state, the red blood cell's ability to function is compromised. Comparatively, if the scenario were reversed and the red blood cell were placed in a hypotonic environment, such as pure water, water would rush into the cell, potentially causing it to swell and burst.
It's important to note that a red blood cell operates optimally in an isotonic solution, where the concentrations of solutes inside and outside the cell are equal, maintaining the cell's normal volume and function.