Question

Isolated plant cells are placed in a solution of 10% sucrose. When a sample of the cells is observed under a microscope after a few minutes in the solution, it is observed that the plasma membrane of each cell has pulled away from the cell wall. Which of the following is the best explanation? A. Solutes only moved out of the cells into the sucrose solution B. Water only moved out of the cells into the sucrose solution C. Sucrose moved into the cells, and water moved out of the cells into the sucrose solution D. Solutes and water both moved out of the cells into the sucrose solution

Answer 1

The plasma membrane of a plant cell pulls away from the cell wall when placed in a hypertonic solution, such as a 10% sucrose solution, due to the process of osmosis. This is observed as water moves out of the cell into the sucrose solution to achieve equilibrium, causing the cell membrane to shrink and detach from the cell wall, a process known as plasmolysis.

Step-by-step explanation:

The explanation for why the plasma membrane of each cell is observed to have pulled away from the cell wall after being placed in a 10% sucrose solution, is that it is an instance of plasmolysis happening, a process commonly observed in plant cells under hypertonic conditions. This is when the cell membrane shrinks and detaches from the cell wall due to water loss.

Hypertonic solutions, like the presented 10% sucrose solution, mean there is a higher concentration of solutes (such as sucrose) in the external solution compared to inside the cell. In response to this imbalance, water moves out of the cells and into the sucrose solution via osmosis to achieve equilibrium, a process described as the solution being hypertonic to the cell.

This loss of water results in the plasma membrane retracting or pulling away from the cell wall, a process known as plasmolysis. Hence, the correct answer is B. Water only moved out of the cells into the sucrose solution.

Learn more about Plasmolysis