A student investigated the effect of different concentrations of sugar solution on pieces of carrot - AQA - GCSE Biology Combined Science - Question 4 - 2018 - Paper 1

To create Figure 7, first choose a suitable scale and label for the y-axis, such as 5 or 6 units per 2 cm. Next, plot the results from Table 2 as points on the graph where the x-axis represents the concentration of sugar solution (in mol/dm³) and the y-axis represents the percentage change in mass. Finally, draw a line of best fit that smoothly connects these points for graphical representation.

From the completed graph in Figure 7, it can be estimated that the concentration of sugar solution inside the carrot cells is approximately 0.6 mol/dm³, as this is where the percentage change in mass becomes negative.

The mass of the carrot in the 0.6 mol/dm³ sugar solution decreased due to the loss of water by osmosis. Specifically, the concentration of water inside the carrot cells was higher than outside in the solution, causing water to move out of the carrot cells into the sugar solution, thereby reducing the mass.

The pieces of carrot did not change in mass when boiled because boiling likely damaged the cell membranes, making them non-selectively permeable. As a result, the cells could not effectively retain or lose water, leading to no significant change in mass.