Biology 0610/52 February/March 2024: question paper and mark scheme

Question

You are going to investigate the effect of glucose concentration on the rate of anaerobic respiration in yeast. Anaerobic respiration in yeast breaks down glucose to form ethanol and carbon dioxide. Anaerobic respiration in yeast causes the blue dye, methylene blue, to become colourless. The time taken for the blue colour to disappear can be used as a measure of the rate of anaerobic respiration in yeast. Read all the instructions but DO NOT DO THEM 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 doing the practical work. Step 1 Label one test-tube 0.0%, one test-tube 0.5% and one test-tube 1.0%. Put the test-tubes in the test-tube rack. Step 2 Put 5.0 cm3 of water into the test-tube labelled 0.0%. Step 3 Put 2.5 cm3 of 1.0% glucose solution and 2.5 cm3 of water into the test-tube labelled 0.5%. Step 4 Put 5.0 cm3 of 1.0% glucose solution into the test-tube labelled 1.0%. Step 5 Stir the contents of the beaker containing the yeast suspension with the glass rod. Step 6 Add 5.0 cm3 of the yeast suspension to each of the test-tubes labelled 0.0%, 0.5% and 1.0%. Step 7 Put all three test-tubes into the beaker labelled water-bath. Raise your hand when you are ready for hot water to be added to the water-bath. Step 8 Start the stop-clock and wait for three minutes. Step 9 After three minutes, remove the test-tubes from the water-bath and place them in the test-tube rack. Step 10 Use a pipette to add one drop of methylene blue dye to each of the test-tubes. Carefully mix the contents of each test-tube with the glass rod. Step 11 Use a second pipette to slowly add a layer of oil to each of the test-tubes. The layer of oil should be approximately 1.0 cm thick. The layer of oil will float on top of the yeast suspension and methylene blue mixture, as shown in Fig. 1.1. layer of oil 1.0 cm to maintain anaerobic conditions test-tube contents Fig. 1.1 Step 12 Put the test-tubes back into the water-bath and restart the stop-clock. Step 13 Measure the time taken for the blue colour in each of the test-tubes to disappear. Record the time taken in seconds for each test-tube in your table in 1(a)(i). If the colour is still blue after 10 minutes, stop timing and record the time as >600 in your table in 1(a)(i). (a) (i) Prepare a table to record your results. [4] (ii) State a conclusion for your results. …… [1] (iii) State the independent variable in this investigation. …… [1] (iv) State one variable that was kept constant in this investigation. …… [1] (v) Explain why it was important to stir the yeast suspension in step 5. …… [1] (b) One way to improve this investigation would be to use an increased number of different concentrations of glucose. (i) Suggest two other ways to improve this investigation. 1 …… 2 …… [2] (ii) Describe how you would make 5.0 cm3 of 0.25% glucose solution using a 0.50% glucose solution and distilled water. …… [2] (iii) Describe the method you would use to test a solution for the presence of glucose. …… [2] (c) A student investigated the effect of temperature on the rate of respiration in yeast at 25 °C and 35 °C. In one experiment, the student measured the volume of carbon dioxide produced by the yeast every 5 minutes for a total of 30 minutes. (i) Describe suitable apparatus that could be used to collect and measure the volume of carbon dioxide produced. …… [1] The student did three experiments at each temperature. They used the results to calculate the mean volume of carbon dioxide produced. Part of the student’s results table for the experiments at 35 °C is shown in Table 1.1. Table 1.1 time volume of carbon dioxide produced at 35 °C / cm3 / minutes experiment 1 experiment 2 experiment 3 mean 15 1.8 3.2 2.0 1.9 (ii) The student decided that the result of one of the experiments shown in Table 1.1 was anomalous. State what is meant by an anomalous result. …… [1] (iii) Describe how the student calculated the mean volume of carbon dioxide produced shown in Table 1.1. …… [1] The results of the whole investigation about the effect of temperature on the rate of respiration in yeast at 25 °C and 35 °C are shown in Table 1.2. Table 1.2 mean volume of mean volume of time carbon dioxide carbon dioxide / minutes produced produced at 25 °C / cm3 at 35 °C / cm3 5 0.0 0.1 10 0.0 0.8 15 0.1 1.9 20 0.2 2.7 25 0.5 3.2 30 1.1 3.2 (iv) Using the data in Table 1.2, compare the mean volumes of carbon dioxide produced at 25 °C and 35 °C. …… [2] (v) Plot a line graph on the grid of mean volume of carbon dioxide produced against time, using all of the data in Table 1.2. You will need to plot the data for each temperature as separate lines on your graph. Include a suitable key. [5] (vi) Estimate the time taken to produce 3.0 cm3 of carbon dioxide at 35 °C. Show on the graph how you obtained your estimate. …… minutes [2] (d) Carbon dioxide gas was bubbled through hydrogencarbonate indicator solution. The indicator was red before the gas was bubbled through. State the colour change that would occur. …… [1] [Total: 27]

Question

(a) Fig. 2.1 shows epidermal cells from a red onion. P Q X magnification ×340 Fig. 2.1 (i) Draw a large diagram of the cell labelled X in Fig. 2.1. [4] (ii) Line PQ on Fig. 2.1 represents the length of cell X. Measure the length of line PQ on Fig. 2.1. length of PQ …… mm Calculate the actual length of cell X using the formula and your measurement. length of line PQ in Fig. 2.1 magnification = actual length of cell X Give your answer to three significant figures. Space for working. …… mm [3] (b) Water moves into and out of cells by osmosis. Plan an investigation to determine the effect of the concentration of sodium chloride solution on osmosis in plant tissue. …… [6] [Total: 13]