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About This Drill
AP Biology — Unit 2 — Membrane Transport & Osmosis — Drill 4 is a practice drill. It contains 5 original questions created by Brian Stewart, a Barron's test prep author with over 20 years of tutoring experience.
Practice interpreting osmosis and membrane transport data in this AP Biology drill on Unit 2 cells. Analyze dialysis bag and potato core experiments, apply water potential concepts, and evaluate claims about plasmolysis and selective permeability.
Passage
A student investigates osmosis and membrane transport using dialysis tubing (a selectively permeable membrane) and potato core cylinders. In Experiment 1, dialysis bags filled with sucrose solutions of varying concentrations are submerged in distilled water for 60 minutes. In Experiment 2, potato cores are submerged in sucrose solutions of varying concentrations for 90 minutes. Mass change is recorded as percent change from initial mass.
| Treatment | Sucrose Concentration (M) | Experiment 1: Dialysis Bag % Mass Change | Experiment 2: Potato Core % Mass Change |
|---|
| A | 0.0 | 0.0 | +8.2 |
| B | 0.2 | +12.4 | +4.1 |
| C | 0.4 | +19.7 | +0.3 |
| D | 0.6 | +24.1 | -3.8 |
| E | 0.8 | +28.3 | -7.4 |
| F | 1.0 | +31.2 | -11.6 |
Questions in This Drill
- Based on the data, what is the approximate solute concentration of the potato core cells?
- In Experiment 1, the dialysis bag filled with 0.0 M sucrose submerged in distilled water shows no mass change. A student claims this proves the dialysis membrane is impermeable to water at low solute concentrations. Which reasoning best refutes this claim?
- A student calculates that between treatments C and D in Experiment 2, the rate of mass loss is approximately 4.1 percentage points per 0.2 M increase in sucrose concentration. Assuming the relationship remains approximately linear over this interval, what percent mass change would be predicted for a potato core submerged in 1.2 M sucrose?
- A researcher proposes that the mass gain observed in dialysis bags (Experiment 1) and the mass loss observed in potato cores at high sucrose concentrations (Experiment 2) are both best explained by the same underlying mechanism. Which explanation best supports this claim?
- A student claims that cells in the potato core at treatment F (1.0 M sucrose) are plasmolyzed. Which evidence from the data is most consistent with this claim, and what would directly confirm it?