INITIAL MASS—
FINAL MASS—
Begin with the balance.
Where does the water go?
Weigh a sample. Soak it. Weigh it again. Explain the evidence for osmosis.
Lab options
Your next action
YOUR MISSION
Why can a solution change the mass of plant tissue?
Test similar-sized potato cylinders in 0.0, 0.3, and 0.6 M sucrose. Weigh each one before and after a modeled 30-minute soak.
Use three fresh cylinders and fresh solution aliquots per concentration. Keep sample preparation, solution volume, temperature, soak time, and blotting method the same. Only solution concentration changes.
3 solutions × 3 samples100 mL solution · 20°CBalance resolution: 0.01 g
The mass response is a stated teaching model, not a prediction for every real potato. The 30-minute soak is shown as a short time-lapse. Real cutting and laboratory procedures require teacher supervision.
Why blot the sample? Why use percentage change?
Liquid clinging to the outside would add mass that did not enter the tissue. Blot gently and consistently before the final weighing. Squeezing the cylinder would introduce another error.
Percentage mass change compares samples with slightly different starting masses: (final mass − initial mass) ÷ initial mass × 100. We calculate it automatically; you can try a calculation yourself at the end.
Water moves in both directions across selectively permeable cell membranes. Our measurements indicate the net effect on tissue mass. Near-zero change is consistent with little net water movement under these conditions; it does not mean that water molecules stopped moving.
Measured evidence
| Sample | Sucrose (M) | Initial (g) | Final (g) | Mass change (%) |
|---|
Fresh samples are used for every repeat. Each sample is weighed, soaked, gently blotted, and reweighed before it enters this table.
3 / COMPARE AND EXPLAIN
Use mass change to follow the water.
Compare the three groups. Which solution produced the least net change in this model tissue?
| Sucrose | Samples | Mean mass change | Observed range |
|---|
Bars show the observed minimum–maximum range, not a confidence interval. Results apply to this modeled tissue and procedure.
Help me explain my results
Measurements from your investigation
These are your recorded model results. Choose the evidence that supports your own conclusion.
- Make a claim.
- Use evidence.
- Explain the science.
- Set a limit.
Before downloading: Does your explanation answer the question, use a number with units, explain why, and state a limit? Revise it above if needed.
This guide does not write or grade your explanation. A teacher reviews your scientific reasoning.
Optional calculation: percentage mass change
The evidence choice is checked automatically. A teacher evaluates the scientific quality of the written explanation.