Cells, Membranes & Exchange — Investigation · Life Science: Biology, Grade 10
Connect cell structures, membrane transport, and exchange with the needs of cells.
Interpret Membrane Exchange Data
Investigate
How does solution concentration affect the mass of a tissue model?
Use three sessions: define question, boundary, model and route; collect or analyze the supplied repeated records; then graph, explain, revise and submit the notebook. Home-study activities do not certify NYSED laboratory minutes or mandated investigations.
Materials
- Supplied paired mass data
- Calculator
- Graph paper
Before you begin
Use the supplied paper-and-data model. This activity requires no biological samples, cultures, personal health information, or tests on people.
Plan a fair test
External concentration is compared while tissue size, duration, temperature, blotting, and measurement method are held comparable. Measure before/after mass for each sample and use percentage change because starting masses differ.
Method
- Predict the direction of water movement under a stated osmosis model.
- For each sample calculate (final − initial) / initial × 100%.
- Average the percentage changes within each concentration.
- Plot concentration versus mean change and estimate where net change would be near zero.
- Explain how sample variability and blotting could affect interpretation.
- Describe what the mass evidence does and does not establish about membrane transport.
Open the investigation data (illustrative)
Illustrative data authored for this activity, not an actual experiment or an official mandated investigation. Use them as supplied evidence, not as your own observations.
| Solution (model units) | Sample | Initial mass (g) | Final mass (g) |
|---|---|---|---|
| 0 | A | 10 | 11 |
| 0 | B | 12 | 13.2 |
| 1 | A | 10 | 10.2 |
| 1 | B | 12 | 12.24 |
| 2 | A | 10 | 9.2 |
| 2 | B | 12 | 11.04 |
Analyze and explain
- Find the mean percentage change at each concentration.
- Estimate a zero-change concentration by a linear interpolation between 1 and 2.
- Why should it be called an estimate rather than the exact internal concentration?
- Separate collected measurements from the supplied illustrative records.
- Explain how labeled mechanisms constrain the pattern rather than only restate the graph.
- Propose a further comparison that could distinguish an alternative explanation.
What a strong explanation includes
- Uses starting mass as the percentage denominator
- Graphs units and mean changes
- Connects the sign of mass change with a stated water-movement model
- Includes tissue, method, and interpolation limitations
- State units, boundary, comparable conditions and model assumptions.
- Retain a first explanation and an evidence-supported revision.
Parent / teacher guide: discuss after the investigation
Mean changes are +10%, +2%, and −8%. A linear interpolation places zero around 1.2 model units. This is an estimate for this tissue and method, not an exact measurement of every cell’s contents. Net mass can be affected by solution on the surface, tissue damage, solute movement, and a nonlinear response. Osmosis concerns water movement, not equal movement of all solutes. A complete response also states the system boundary, units, matched conditions and limitations. Distinguish supplied illustrative outcomes from collected measurements, and explain why your revised mechanism fits the relevant evidence. Different observations should be interpreted rather than replaced to match the example.
Compare this model with the learner’s actual evidence. Different measurements can support a different conclusion; check the reasoning and limitations, not matching wording.