can let some compounds pass through them, while restricting most
others. Water can usually pass freely, and its molecules tend to distribute themselves
In the diagram below, let us assume that we have
two solutions in physical communication, but separated by a
membrane that will only let water through.
- Solution on the left
is relatively short on salts (hypotonic)
- Solution on the right has a surplus of salts (hypertonic)
- Only water can move through the membrane
"surplus" water in the left chamber would move into the
right-hand chamber, making it swell, as seen on the right
What would happen if you put cells in water?
Remember, that the cell membrane lets water through and cells
have lots of salts and other dissolved substances, whereas water
would have little salt.