For each of the situations below use an arrow to indicate the net movement of sugar into or out of the cell. (Assume that the sugar molecules can pass through the cell membrane in each case.) The three scenarios are: 1) Cell with 1% sugar in a solution of 5% sugar. 2) Cell with 3% sugar in a solution of 1% sugar. 3) Cell with 1% sugar in a solution of 1% sugar.

Answer

The movement of molecules across a membrane from an area of higher concentration to an area of lower concentration is called diffusion. The net movement will occur until equilibrium is reached. In Scenario 1: The sugar concentration outside (5%) is higher than inside (1%). Therefore, the net movement of sugar is INTO the cell (indicated by an arrow pointing into the circle). In Scenario 2: The sugar concentration inside (3%) is higher than outside (1%). Therefore, the net movement of sugar is OUT of the cell (indicated by an arrow pointing away from the circle). In Scenario 3: The sugar concentration is the same inside (1%) and outside (1%). There is no net movement of sugar (no arrow is needed, or a double-headed arrow can indicate dynamic equilibrium).