Question

a laboratory technician places red blood cells into three different solutions. observations are recorded each minute for five minutes.

solution	1 min.	2 min.	3 min.	4 min.	5 min.
solution 2	no change	no change	no change	no change	no change
solution 3	no change	cells are slightly smaller	cells are much smaller	cells look wilted	nothing that looks like a cell can be seen

which of the following best explains what is causing the red blood cells in solution 3 to change size over the five - minute period?
a solute is leaving the cells faster than it is entering the cells.
b water is leaving the cells faster than it is entering the cells.
c the cells are making new protein.
d the cell’s membranes are dissolving.

Explanation:

To determine the cause of the red blood cell size change in Solution 3, we analyze osmosis. In Solution 3, the cells become smaller and eventually disappear, indicating water loss. Osmosis involves water movement across a semipermeable membrane. If water leaves the cells faster than it enters, the cells shrink (plasmolysis).

• Option A: Solute movement is less likely as solutes (like ions) have restricted movement across cell membranes compared to water.
• Option B: If water leaves faster than it enters, cells shrink, which matches the observation (cells become smaller, wilted, then unrecognizable).
• Option C: Protein synthesis doesn't cause rapid size changes observed here.
• Option D: Cell membranes don't dissolve in typical osmotic solutions; the change is due to water movement, not membrane dissolution.

So, the best explanation is that water is leaving the cells faster than it is entering.

Answer:

B. Water is leaving the cells faster than it is entering the cells.