If there is no variation in shell thickness within a population of snails, and no mutations occur, what happens to shell thickness in response to crab predation? (hint: recall your experiment in the second exercise, when you turned variation off.)

Ihave made a synthetic cell by placing a solution that is 10% sodium chloride inside a semipermeable membrane through which water can pass but not sodium chloride. if i place this cell into a solution that is 20% sodium chloride what will happen to the size of the cell? will it increase, decrease, or stay the same in size?