Question

question 4.
dialysis tubing was filled with an unknown solution to represent a cell. the cell was submerged in distilled water, and then in an increasingly saline (salty) solution (consisting of the diagrams labeling) is plotted on the graph below. assume the diagrams labeling is impermeable to na and cl ions that make up nacl.
which statement best describes the conditions in which the contents of the cell and its environment are isotonic?
a. the cell lost mass in a hypotonic solution, suggesting water moved out of the cell.
b. the cell did not change in mass when placed in a solution of approximately 0.65 m nacl indicating an isotonic environment.
c. the cell lost mass when placed in distilled water, indicating it was in a hypertonic environment.
d. the cell gained mass in a hypertonic solution, showing that solutes moved into the cell.

Explanation:

When a cell and its environment are isotonic, there is no net movement of water. This means the cell does not change in mass. In option B, it indicates an isotonic environment (0.65 M NaCl where no mass change occurs). In a hypotonic solution (option A), water would move into the cell (cell gains mass), in a hypertonic environment (option C) water moves out (cell loses mass), and in a hypertonic solution (option D) solutes don't move into the cell (water moves out instead).

Answer:

B. The cell did not change in mass when placed in a solution of approximately 0.65 M NaCl indicating an isotonic environment.