SAMPLE 1 - OSMOSIS1. An experiment was carried out to investigate the effect of different concentration of sucrose solution on potato discs. The following steps were carried out. Step 1 : A cork borer was used to obtain 50 potato discs of uniformed size. Step 2 : The potato discs were divided into 5 groups, P,Q, R, S and T. Each group contains 10 potato discs which were placed in five different petri dishes. Step 3 : Distilled water and sucrose solution with different concentration was poured into each petri dish as shown in Table 1. Group Solution P Distilled water Q 0.2 mol dm-3 sucrose solution R 0.4 mol dm-3 sucrose solution S 0.6 mol dm-3 sucrose solution T 0.8 mol dm-3 sucrose solution Table 1 Step 4 : The length of each group of potato strip was measured before the immersion by arranging the discs on a callibrated cardboard as shown in Diagram 1. Diagram 1 Step 5 : The potato discs were then immersed in each solution for 30 minutes. After 30 minutes, the discs were then arranged on the callibrated cardboard. 1 .... [3 marks] 2 .........Table 2 shows the results of this experiment.... Concentration of solution (mol dm-3) 0...............8 Length of 10 discs after immersion for 30 minutes / cm cm 0 1 2 3 4 5 6 7 83 9 10 11 12 cm 0 1 2 3 4 5 6 7 83 9 10 11 12 cm 0 1 2 3 4 5 6 7 83 9 10 11 12 cm 0 1 2 3 4 5 6 7 83 9 10 11 12 cm 0 1 2 3 4 5 6 7 83 9 10 11 12 Table 2 a. …………………………………………………………………………….. ……………………………………………………………………………...... (i) State two different observations made from Table 2. 1 ……………………………………………………………………………....6 0.0 0........4 0............2 0...... 2 …………………………………………………………………………….... .....………………………….. ……………………………………………………......................... c........... Variable Manipulated variable Method to handle the variable ……………………………..... Constant variable .................. ……………………………………………………...... ……………………………………………………...................... ……………………………... ……………………………...... ……………………………………………………........................ [3 marks] Complete Table 3 based on this experiment.. ………………………………………………………………………………….......................... . [3 marks] 3 ... Responding variable ............. Inference from observation 1 : ………………………………………………………… …………………………………………………………………………………........ Table 3 [3 marks] d................................. ……………………………. ……………………………........ ……………………………………………………........ ……………………………………………………. ...(ii) State the inference which corresponds to the observations in 1(a)(i)............... Inference from observation 2 : ………………………………………………………….............. …………………………………………………….................... …………………………………………………….. ……………………………....... …………………………….....………………………….................. State the hypothesis for this experiment................... …………………………………………………….... [3 marks] b....... Record the length of potato discs after 30 minutes immersion in the boxes provided in Table 2....... (i) Construct a table and record all the data collected in this experiment. Using the data in e(i).e. draw the graph of change in length against concentration of sucrose solution. [3 marks] 4 . Your table should have the following titles : Concentration of sucrose solution Length of 10 discs before 30 minutes immersion Length of 10 discs after 30 minutes immersion Change in length [3 marks] (ii) Use the graph paper provided on page 5 to answer this part of the question. Graph of change in length of potato discs against concentration of sucrose solution. 5 . .........................................................f....................................................... He is provided with the following materials : Visking tubing Egg shell Cellophane tape Muslin cloth Plastic Classify the materials above according to its permeability................................................................................. explain the relationship between the concentration of sucrose solution to the change in length of potato discs........................... ................... ......... Explain your prediction................................................................................................................................................................ Predict the change in diameter of the potato discs.......................................................................................... Based on the graph in e(ii). [3 marks] g.......................... .......................................................... Based on the result from this experiment.......................................................................................................... 6 .............. ................. what can be deduced about osmosis ? ..................... ................................. If the experiment is repeated using potato discs of the same diameter but different thickness..................................... ................................................................................................................................................................................................................................................................................................................ ................................ ............ [3 marks] i...................... [3 marks] h....................................................... Another student wishes to investigate the movement of substances across the plasma membrane..................................... [3 marks] 7 .