Biology 0610/52 February/March 2019: question paper and mark scheme

Question

You are going to investigate the effect of two different types of washing powder on stained cloth. One of these is biological and contains enzymes and detergent. The other is non-biological and contains only detergent. You are provided with: • four pieces of dry cloth that have been stained with the same food • a solution of biological washing powder in a beaker labelled bio • a solution of non-biological washing powder in a beaker labelled non-bio • distilled water in a beaker labelled water. Read all the instructions but DO NOT CARRY THEM OUT until you have drawn a table for your results in the space provided in 1(a)(i). You should use the safety equipment provided while you are carrying out the practical work. Step 1 Use a marker pen to divide a white tile into four sections. Label the four sections bio, non-bio, water and not washed as shown in Fig. 1.1. bio non-bio water not washed Fig. 1.1 Step 2 Place one piece of stained cloth on the not washed section of the white tile. Step 3 Put one piece of stained cloth into each of the beakers labelled bio, non-bio and water. Step 4 Use a glass rod to push the pieces of cloth into the liquid in each beaker. Stir the liquid in each beaker for 10 seconds. Step 5 Start a stop-clock. Step 6 After 5 minutes, stir the liquid in each beaker for 10 seconds. Step 7 Let the pieces of cloth soak in the liquid for a further 5 minutes and then repeat step 6. Step 8 Remove the pieces of cloth from the beakers and place them on the labelled sections of the white tile. Step 9 Observe the stain on each piece of cloth and use the intensity score in Table 1.1 to match the intensity of the stain on each piece of cloth. Record the intensity score in your table in 1(a)(i). Table 1.1 intensity score lowest intensity + ++ +++ highest intensity ++++ (a) (i) Prepare a table to record your results in the space provided. [4] (ii) State one variable that was kept the same in this investigation. …… [1] (iii) Identify one source of error in step 4 and explain how it might affect the results. error …… explanation …… [2] (iv) Identify a control in this experiment and explain why this control was used. …… [2] (v) State why the method used in step 9 may not give accurate results. …… [1] (b) Some students wanted to find the optimum (best) temperature for using biological washing powder. A Petri dish was filled with agar jelly containing starch. A circular hole was cut into the centre of the agar. A solution of the biological washing powder was put into the hole. The Petri dish was incubated at 10 °C for 10 hours. After 10 hours iodine solution was poured onto the agar in the Petri dish. This procedure was repeated at different temperatures. A typical result is shown in Fig. 1.2. hole with washing powder solution agar stained pale brown agar stained blue-black Fig. 1.2 (i) State the variable that was changed (independent variable) in the investigation described in 1(b). …… [1] (ii) Some of the agar is stained blue-black and some is stained pale brown. State a conclusion for this result. …… [1] (iii) The diameter of the pale brown stained area was measured during the investigation. The results are shown in Table 1.2. Table 1.2 diameter of pale brown temperature / °C stained area / mm 10 11 20 14 30 18 40 22 50 22 60 7 70 5 Plot a line graph on the grid of the data in Table 1.2. [4] (iv) Describe the trend shown by the data in Table 1.2 and your graph. …… [2] (v) The students were unable to determine the optimum temperature from their results. Describe what additional measurements would be needed to find the optimum temperature. …… [2] [Total: 20]

Question

Fig. 2.1 shows photomicrographs of lung tissue at the same magnification. One shows healthy lung tissue and the other shows lung tissue from a person with COPD. Line AB shows the diameter of one healthy alveolus. Line CD shows the diameter of an area of lung where the alveoli have been destroyed. alveolar wall C D A B healthy COPD Fig. 2.1 (a) (i) Make a large drawing of the lung tissue of the person with COPD shown in Fig. 2.1. Do not draw individual cells. [4] (ii) Measure the length of CD as shown on Fig. 2.1. Include the unit. length of CD …… Mark on your drawing the position of the line CD and measure the length of the line you have drawn. Include the unit. length of line on your drawing …… Calculate the magnification of your drawing. Give your answer to the nearest whole number. magnification = length of line on your drawing length of CD on Fig. 2.1 Space for working. [3] (iii) Describe three visible ways that the lungs of the healthy person differ from the person with COPD in Fig. 2.1. 1 …… 2 …… 3 …… [3] (b) Some students decided to investigate the concentration of carbon dioxide in expired air compared to that in inspired air. They used the apparatus shown in Fig. 2.2 by breathing into the tube labelled T. T inspired air expired air air enters air exits A B limewater Fig. 2.2 (i) Suggest one possible hazard in this investigation. …… [1] (ii) State one other substance which could be used instead of limewater to determine the concentration of carbon dioxide. …… [1] (iii) When the students used the apparatus shown in Fig. 2.2, inspired air passed through the limewater in test-tube A and expired air passed through the limewater in test-tube B. The students timed how long it took for the limewater in test-tubes A and B to go cloudy. Their results are shown in Table 2.1. Table 2.1 time taken for limewater to go cloudy / s test-tube A test-tube B 600 6 The concentration of carbon dioxide in inspired air is 0.04%. Calculate, using the results in Table 2.1, the concentration of carbon dioxide in expired air. Show your working. …… % [2] (c) A student wanted to investigate the hypothesis: ‘Expired air contains more carbon dioxide immediately after exercise than before exercise.’ Plan an investigation using the apparatus shown in Fig. 2.2 to test this hypothesis. [6] [Total: 20]