A student investigated the effect of different concentrations of sugar solution on pieces of potato - AQA - GCSE Biology Combined Science - Question 1 - 2020 - Paper 1

The potato in the 0.0 mol/dm² sugar solution increased in mass because the surrounding solution was pure water. Water entered the potato cells through osmosis, moving from an area of higher water concentration (the solution) to an area of lower water concentration (inside the potato). As a result, the potato gained water, which resulted in an increase in mass.

To complete Figure 1, plot all data points from Table 1 on the graph with 'Concentration of sugar solution in mol/dm²' on the x-axis and 'Change in mass in grams' on the y-axis. Then, draw a line of best fit through these points, ensuring it reflects the trend of the data.

From Figure 1, read the concentration at which the potato mass remains unchanged. This value is around 0.23 to 0.24 mol/dm², indicating the concentration of sugar solution inside the potato cells.

Using Table 1, the change in mass for the potato in 0.2 mol/dm² is 0.25 grams and the starting mass is 7.96 grams.

Using the formula:

$ext{percentage change in mass} = \left( \frac{0.25}{7.96} \right) \times 100$

Calculating this gives:

$\left( \frac{0.25}{7.96} \right) \times 100 \approx 3.14\%$

Thus, the percentage change in mass to three significant figures is 3.14%.