IB Biology SL D2.3.4 Changes in Plant Tissue Questions

Use plant-tissue osmosis data to calculate percentage mass change, locate the zero-change intercept, explain tissue differences and judge experiment reliability in IB Biology SL D2.3.4.

Exam points

Use percentage-mass changes to calculate plant-tissue osmolarity from the zero-change point of a graph.
Read graph trends relative to the isotonic point to identify hypotonic solutions and count potato cylinders that lose mass.
Explain different isotonic points for plant tissues by referring to their internal dissolved solutes or growth and storage conditions.
Explain why percentage mass change allows fair comparison when tissue samples have different starting masses.
Evaluate plant-tissue graph reliability using trend, scatter, error bars or outlier evidence.
Describe controls for a plant-tissue osmolarity experiment, such as sample size, solution exposure time, temperature and drying method.

[Maximum number: 3]

An experiment was carried out to determine the change in mass due to osmosis. Potato cubes were soaked in different concentrations of sodium chloride for 12 hours. The table shows the mean data for the mass of potato before and after the 12-hour period.

Table for Question IB Biology SL D2.3.4 Changes in Plant Tissue Questions question 1 — IB Biology SL

(a)

Explain how the data may be used to determine the solute concentration of the potato tissue.

[ 2 ]

(b)

Estimate the solute concentration of the potato tissue.

[ 1 ]

Any number from $0.31 \mathrm{~mol} \mathrm{dm}^{-3}$ to $0.39 \mathrm{~mol} \mathrm{dm}^{-3}$ ;

Units required.

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IB Biology SL D2.3.4 Changes in Plant Tissue Questions question 1

Question (a)

Question (b)