Final answer:
The cell surviving in a 4% salt solution suggests its internal salt concentration creates an isotonic environment, where solute concentration inside and outside the cell is approximately equal, leading to no net movement of water. The correct option is b.
Step-by-step explanation:
The survival of a cell in a solution of pure water versus 4% salt water provides insight into the cell's normal salt concentration. When a cell is placed in pure water, which is a hypotonic solution, it experiences a net influx of water, leading to the cell swelling and potentially bursting. In contrast, when in 4% salt water, the cell may be in a hypertonic solution, resulting in water exiting the cell and causing it to shrink.
If the cell survives in both environments but maintains its normal shape better in the salt solution, this suggests that the interior of the cell is closer in osmolarity to the 4% salt water, making this environment closer to an isotonic solution for the cell. Therefore, the correct answer to what the survival of the cell tells us about its internal salt concentration in these conditions would likely be (c) Isotonic solution, if the cell remains stable in the 4% salt water.
The survival of a cell in a solution of pure water and 4% salt water tells us that the concentration of salt within the cell is less than 4% and higher than 0%. Based on this information, we can conclude that the solution is a hypotonic solution for the cell.