In an experiment involving planar phospholipid bilayers, a solution of table salt (sodium and chloride ions in water) is added on the left side of the membrane while pure water is added on the right side. After 30 minutes the researchers test for the presence of ions on each side of the membrane. The right side tests negative for ions. What can you conclude?
a) The experiment failed.
b) Ions cannot readily cross phospholipid bilayers.
c) The water somehow blocked the movement of ions across the membrane.
d) The left side would probably also test negative for ions.
e) The salt most likely precipitated out of solution
Answer: B