Biology 0610/63 October/November 2024: question paper and mark scheme

Question

Amylase is an enzyme found in the human body that catalyses the breakdown of starch into reducing sugars. Tea contains a chemical called tannin which affects amylase activity in the body. A student investigated the effect of tea on the enzyme amylase. The student used this method: Step 1 Label three test-tubes S1, S2 and S3. Step 2 Put 2 cm3 of starch suspension into all three test-tubes. Step 3 Label another three test-tubes A, AT and T. Step 4 Put 2 cm3 of amylase solution into test-tube A and 2 cm3 of amylase solution into test-tube AT. Step 5 Put 2 cm3 of tea into test-tube AT and 2 cm3 of tea into test-tube T. The test-tubes are shown in Fig. 1.1. starch starch starch S1 S2 S3 amylase and tea amylase tea A AT T Fig. 1.1 Step 6 Place all six test-tubes into a hot water-bath. Step 7 Use a marker pen to label three sections on a white tile, as shown in Fig. 1.2. Step 8 Add 10 drops of iodine solution to each section, as shown in Fig. 1.2. A AT T white tile first drop of yellow-brown iodine solution Fig. 1.2 Step 9 Start the stop-clock and pour the starch suspension in test-tube S1 into test-tube A. Step 10 Use a pipette to immediately remove a drop of the mixture from test-tube A and place it onto the first drop of iodine solution in section A on the white tile. Return any mixture still in the pipette to test-tube A. Step 11 Repeat step 10 every 30 seconds, until all 10 drops of iodine solution in section A have been used. Reset the stop-clock to zero. Step 12 Repeat steps 9 to 11 using test-tubes S2 and AT and section AT on the white tile. Step 13 Repeat steps 9 to 11 using test-tubes S3 and T and section T on the white tile. The student’s results are shown in Fig. 1.3. key: A AT T blue-black colour yellow-brown colour Fig. 1.3 (a) The student needed to identify when all of the starch had been broken down in each test-tube. (i) Describe how the student can tell if the starch has been broken down. …… [1] (ii) Prepare a table to record the results from Fig. 1.3. Include in your table the time taken, in seconds, for starch to be broken down in all three test-tubes. If starch remained after testing with all 10 drops of iodine solution, record this as >270. [3] (iii) State what can be concluded about the effect of tea on amylase activity. …… [1] (iv) State the independent variable in this investigation. …… [1] (v) State one variable that was kept constant in this investigation. …… [1] (vi) Test-tube T did not contain amylase and was used as a control. Suggest a reason for including a control in this investigation. …… [1] (vii) Explain why all of the test-tubes were placed in a water-bath in step 6 before the contents of the test-tubes were mixed in step 9. …… [1] (viii) A student stated that there is an error in step 4 and step 5. Identify this error and suggest how the procedure should be improved. error …… improvement …… …… [2] (ix) Describe a test which would show that reducing sugars have been produced. …… [2] (b) Fig. 1.4 is a photograph of a tea leaf. Fig. 1.4 Make a large drawing of the tea leaf shown in Fig. 1.4. [4] (c) Biological washing powders contain enzymes that help to remove stains from clothes. This reduces the need to wash clothes at high temperatures. Plan an investigation to determine the optimum temperature for a biological washing powder. …… [6] [Total: 23]

Question

(a) Fig. 2.1 is a photograph of a villus, from one part of the small intestine. A B magnification × 210 Fig. 2.1 (i) The length of line AB represents the width of the villus in Fig. 2.1. Measure the length of line AB. length of line AB …… mm Use your measurement and the formula to calculate the actual width of the villus. length of line AB in Fig. 2.1 magnification = actual width of villus Give your answer to two significant figures. Space for working. …… mm [3] (ii) Fig. 2.2 shows a villus from a different part of the small intestine. magnification × 210 Fig. 2.2 State two ways the villus in Fig. 2.2 differs from the villus in Fig. 2.1. 1 …… 2 …… [2] (b) A scientist studied the length of the small intestine in different animals. The scientist recorded: • the body length of five different animals • the length of the small intestine of each animal. For each animal, the length of the small intestine was divided by the body length. Table 2.1 shows the scientist’s results. Table 2.1 type of small intestine length animal divided by the body length cat 4 cow 20 dog 6 horse 12 human 5 (i) Plot a bar chart on the grid of the data in Table 2.1. [4] (ii) Identify the dependent variable in this study. …… [1] (iii) The horse used in the study had a body length of 2.1 m. The small intestine length divided by the body length for the horse was 12. Calculate the length of its small intestine. Include the unit. …… [2] (iv) Table 2.2 also shows the main diet of the five animals in the study. Table 2.2 type of small intestine length diet animal divided by the body length cat animals 4 cow plants 20 dog animals 6 horse plants 12 human plants and animals 5 Describe the relationship between the small intestine length divided by the body length and the diet of the animals. …… [2] (v) Suggest why the scientist divided the small intestine length by the body length for each animal rather than looking at just the intestine length. …… [1] (vi) Suggest two possible improvements to the method used in this study. 1 …… 2 …… [2] [Total: 17]