MDG #5 - Do fish explode?

CQ#1: You are looking at solutes (red dots) after plenty of time elapsed. Most of the dots are on the left. This means:

• The solutes can cross the membrane

• The solutes cannot cross the membrane

A solution is 90% water on the left, and 80% water on the right, of a membrane that only water can cross. Assuming no other forces are operating, which direction will water move?

• Water will move from left to right.

• Water will move from right to left.

• It depends

• It is impossible to tell.

CQ#3: The solution on the left is 10% salt. On the right is 5% salt. Salt cannot cross the membrane, but water can. Which way will the water move?

• 1. Water will move from left to right

• 1. Water will move from right to left

• 1. It depends

• 1. It is impossible to tell

What do you predict will happen when you place an animal cell in a container of distilled water?

• Water will not move

• Water will move from the cell into the beaker holding the experiment

• Water will move into the cell for a while

• Water will move into the cell and the cell will explode

The plant cell doesn’t explode because…

• Plants are tougher than animals

• Plants have a cell wall that pushes back against the increased cell volume

• Plants don't let water cross membranes

• We have no idea

Why don’t freshwater fish explode?

• They really do, but underwater where we don't see it

• They don't explode because they have cell walls

• They don't explode because they have kidneys to get rid of excess water