Which of the following experimental procedures would best test whether osmosis has occurred in a biological sample?

• A. Measuring the temperature change of a solution over time.
• B. Measuring the change in mass of a dialysis bag filled with sucrose solution after placing it in distilled water.
• C. Counting the number of cells under a microscope before and after incubation.
• D. Observing the color change of a pH indicator in a solution.

Answer: (B)

Verified step by step guidance

1. Understand the concept of osmosis: Osmosis is the movement of water molecules across a selectively permeable membrane from an area of lower solute concentration to an area of higher solute concentration. This process often results in a change in mass or volume of the biological sample.
2. Identify the experimental procedure that directly measures the effect of osmosis: Among the options provided, measuring the change in mass of a dialysis bag filled with sucrose solution after placing it in distilled water is the most relevant. This is because the dialysis bag acts as a selectively permeable membrane, allowing water to move in or out based on the concentration gradient.
3. Set up the experiment: Fill a dialysis bag with a sucrose solution and seal it properly to prevent leakage. Weigh the bag to record its initial mass.
4. Place the dialysis bag in distilled water: Submerge the bag in a container of distilled water and allow it to sit for a specified period of time, ensuring that osmosis can occur.
5. Measure the final mass of the dialysis bag: After the incubation period, remove the bag from the distilled water, dry its surface, and weigh it again. Compare the initial and final masses to determine if osmosis has occurred, as a change in mass indicates water movement.