26   8 The effect of the concentration of sucrose solution on the mass of potato cylinders was investigated. The cylinders were cut from the same potato and had the same volume. The initial mass of each cylinder was recorded. The cylinders were left in the same volume of each solution for the same length of time. The final mass of each cylinder was recorded. The diagram shows the five test tubes, A, B, C, D and E, that were set up in this investigation. The investigation was then repeated twice. potato cylinder sucrose solution A B C D E 27   Turn over (a) The table shows the results of this investigation. Test tube Concentration of sucrose solution / mol dm–3 Mean initial mass of potato cylinder / g Mean final mass of potato cylinder / g A 0.0 2.79 3.82 B 0.4 2.75 2.67 C 0.6 2.68 2.31 D 0.8 2.71 2.21 E 1.0 2.79 2.01 (i) For test tube E the range of the initial mass was 2.79 ± 0.04 g and the range of the final mass was 2.01 ± 0.16 g. Calculate the largest percentage change in mass for potato cylinders in 1.0 mol dm–3. (2) Answer ..............................................................% (ii) Explain the change in mass for potato cylinders in test tube E. (2) ..................................................................................................................................................................................................................................................................................... ..................................................................................................................................................................................................................................................................................... ..................................................................................................................................................................................................................................................................................... ..................................................................................................................................................................................................................................................................................... ..................................................................................................................................................................................................................................................................................... ..................................................................................................................................................................................................................................................................................... 28   (b) Describe how this investigation could be modified to determine the concentration of sucrose solution that does not change the mass of the potato cylinders. (3) ..................................................................................................................................................................................................................................................................................... ..................................................................................................................................................................................................................................................................................... ..................................................................................................................................................................................................................................................................................... ..................................................................................................................................................................................................................................................................................... ..................................................................................................................................................................................................................................................................................... ..................................................................................................................................................................................................................................................................................... ..................................................................................................................................................................................................................................................................................... ..................................................................................................................................................................................................................................................................................... ..................................................................................................................................................................................................................................................................................... ..................................................................................................................................................................................................................................................................................... ..................................................................................................................................................................................................................................................................................... 29   (c) Beetroot cell vacuoles contain a red pigment called betalain. A student investigated the effect of ethanol on the permeability of beetroot membranes. Test tubes were set up as shown in the diagram, each with a different concentration of ethanol. 20 cm3 ethanol beetroot disc The test tubes were placed in a thermostatically controlled water bath at 25 °C for 30 minutes. The beetroot discs were removed from the ethanol. (i) Calculate the volume of a beetroot disc with a diameter of 1 cm and a height of 5 mm to one decimal place. Include the appropriate unit. Use the formula V = πr2h (2) Answer .............................................................. Turn over 30   (ii) The relative colour of the ethanol after 30 minutes was measured using a colorimeter. The results of the investigation are shown in the graph. Relative colour of the ethanol solution Concentration of ethanol Explain the results of this investigation. (2) ..................................................................................................................................................................................................................................................................................... ..................................................................................................................................................................................................................................................................................... ..................................................................................................................................................................................................................................................................................... ..................................................................................................................................................................................................................................................................................... ..................................................................................................................................................................................................................................................................................... ..................................................................................................................................................................................................................................................................................... 31   (iii) Devise a valid investigation to compare the effects of ethanol and propanol on the permeability of beetroot membranes. (4) ..................................................................................................................................................................................................................................................................................... ..................................................................................................................................................................................................................................................................................... ..................................................................................................................................................................................................................................................................................... ..................................................................................................................................................................................................................................................................................... ..................................................................................................................................................................................................................................................................................... ..................................................................................................................................................................................................................................................................................... ..................................................................................................................................................................................................................................................................................... ..................................................................................................................................................................................................................................................................................... ..................................................................................................................................................................................................................................................................................... ..................................................................................................................................................................................................................................................................................... ..................................................................................................................................................................................................................................................................................... ..................................................................................................................................................................................................................................................................................... ..................................................................................................................................................................................................................................................................................... ..................................................................................................................................................................................................................................................................................... (Total for Question 8 = 15 marks) TOTAL FOR PAPER = 80 MARKS 32   BLANK PAGE