Final answer:
To demonstrate plasmolysis, a plant cell with an internal solute concentration of 0.8 m must be suspended in a hypertonic solution stronger than its internal solute concentration; hence, the correct answer is d. 1.0 m.
Step-by-step explanation:
To demonstrate plasmolysis in a plant cell with an internal solute concentration of 0.8 m, you would need to suspend the cell in a hypertonic solution, which has a higher solute concentration than the cell itself. In this case, the correct answer is d. 1.0 m. Plasmolysis occurs when the cell membrane detaches from the cell wall due to the loss of water from the cell, which happens when the plant cell is placed in a hypertonic solution.
Plasmolysis results from placing a plant cell in an environment where the external solute concentration is higher than the internal solute concentration, leading to the outward movement of water. This creates a hypertonic condition that causes the cell membrane to shrink and detach from the cell wall. To achieve plasmolysis, the solution needs to be hypertonic relative to the cell's internal solution.