A student is investigating the process of osmosis. She fills a medicine dropper with red blood cells. Next, she creates a saline solution that is isotonic to the red blood cells. What will most likely happen to the red blood cells after they are placed in the solution?

Question

a
Water will neither enter or exit the cells and their sizes will remain the same.
b
Water will exit the cells and cause them to shrink in size.
c
Water will enter the cells and cause them to grow in size.
d
Water will enter and exit the cells at a steady rate and their sizes will remain the same.

Answer 1

The correct answer is a: Water will neither enter nor exit the cells and their sizes will remain the same.

In an isotonic solution, the concentration of solutes (such as saline) outside the red blood cells is equal to the concentration of solutes inside the cells. As a result, there is no net movement of water into or out of the cells, keeping their size stable.