ACJC 2024 H2 Biology P4 Prelim (A)

This document consists of 19 printed pages. [Turn over Anglo-Chinese Junior College JC2 Biology Preliminary Examination Higher 2 CANDIDATE NAME FORM CLASS TUTORIAL CLASS INDEX NUMBER BIOLOGY Paper 4 Practical Candidates answer on the Question Paper. Additional Materials: As listed in the Confidential Instructions. 9744/04 06 August 2024 2 hours 30 minutes READ THESE INSTRUCTIONS FIRST Write your Name, Class and Index number in the spaces on all the work you hand in. Give details of the practical shift and laboratory, where appropriate in the boxes provided. Write in dark blue or black pen. You may use an HB pencil for any diagrams or graphs. Do not use staples, paper clips, glue or correction fluid. Answer all questions in the spaces provided on the Question Paper. The use of an approved scientific calculator is expected, where appropriate. You may lose marks if you do not show your working or if you do not use appropriate units. At the end of the examination, fasten all your work securely together. The number of marks is given in brackets [ ] at the end of each question or part question. Shift Laboratory For Examiners’ use 1 / 12 2 / 23 3 / 20 Total / 55

2 Anglo-Chinese Junior College H2 9744 Paper 4 Preliminary Examination For Examiner Use Answer all questions. 1 In some countries, certain plants have seasonal growth. During the summer plants transport sucrose from the leaves to store it as starch in the roots. Table 1.1 summarises the changes in the leaves and roots during the year. Table 1.1 season leaves roots summer leaves synthesise sucrose sucrose stored as starch winter no leaves starch stored spring leaves growing starch converted to glucose You are required to identify the source of four plant extracts. These have been taken from • a root in winter • a root in spring • phloem sap from the stem in summer • phloem sap from the stem in winter (a) Use the information in Table 1.1 to predict which substances you would expect to be present in each of the four plant extracts, then complete Table 1.2. Key: ✓ (tick) substance present in plant extract ✗ (cross) substance absent from plant extract Table 1.2 source of plant extract substances present in each of the plant extracts starch sucrose glucose root in winter ✓ ✗ ✗ root in spring ✓ or ✗ ✗ ✓ phloem sap from the stem in summer ✗ ✓ ✗ phloem sap from the stem in winter ✗ ✗ ✗ [2] 1m for first two rows, 1m for last two rows;

3 [Turn over Anglo-Chinese Junior College H2 9744 Paper 4 Preliminary Examination For Examiner Use One sample was taken from each of the four plant extracts shown in Table 1.2. You are required to identify from which plant extract each of the four samples S1, S2, S3 and S4 was taken. You are provided with: • Benedict’s solution, in a container labelled B • iodine solution, in a container labelled I • hydrochloric acid, in a container labelled H • sodium hydrogencarbonate powder, in a container labelled S • a source of heated water. Hydrochloric acid H and sodium hydrogencarbonate S are irritants, Benedict’s solution B is harmful and iodine solution I is a stain. Suitable eye protection should be worn. If any of these reagents come into contact with your skin, wash off immediately under cold water. Do not carry out any tests until you have read the instructions on pages 3 to 5. (b) Describe the two tests that show that starch and glucose are present in a plant extract. test for starch: On a white tile, place 3 drops of sample, then add 1 drop of iodine; OR To 1 cm3 of sample, add 3 drop of iodine; ………………………………………………………………………………………….................... [1] test for glucose: 1. To 2 cm3 of sample, add 2 cm3 of Benedict’s solution (volume must be 1:1); 2. Heat in a boiling water bath for 2 minutes (min 1 minute, max 3 minutes); ………………………………………………………………………………………….................... [2]

4 Anglo-Chinese Junior College H2 9744 Paper 4 Preliminary Examination For Examiner Use For the test for sucrose, refer to steps 1 to 9. 1 Before starting the test for sucrose, perform the test for glucose you have described in (b). (c) Explain why the test for glucose must be conducted before the test for sucrose can be carried out. 1. The test for sucrose / non-reducing sugar test involves hydrolysis of sucrose / non- reducing sugar to form glucose / reducing sugar; 2. Hence necessary to test for the absence of glucose / reducing sugar at the start; OR 3. The test for sucrose / non-reducing sugar will eventually still involve a test for glucose / reducing sugar / Benedict’s test; 4. Hence necessary to test for the absence of glucose / reducing sugar at the start; …………………….…………………………………………………………………………............ [2] 2 To start the test for sucrose, put 2.0 cm3 of a fresh sample into a test-tube. 3 Put 2.0 cm3 of H into the same test-tube. 4 Shake the test-tube gently to mix the contents. 5 Put the test-tube in a boiling water-bath. Leave the test-tube for 2 minutes. 6 After 2 minutes, remove the test-tube from the water-bath and put it in a test-tube rack. 7 Leave the test-tube to cool for a further 3 minutes. 8 After 3 minutes, put a small amount of S into the test-tube. The mixture will fizz and rise up the test-tube. Continue to add small amounts of S until there is no more fizzing. Note: there may be a little of S left in the bottom of the test-tube. This will not affect the results. 9 Perform the test for glucose you have described in (b) on the solution from step 8.

5 [Turn over Anglo-Chinese Junior College H2 9744 Paper 4 Preliminary Examination For Examiner Use Proceed as follows. Use the beaker labelled hot water to collect approximately 400 cm 3 of hot water from where it is provided in the laboratory. Heat the water to boiling, if needed. Select the appropriate reagents from those provided and carry out suitable tests to identify the samples S1, S2, S3 and S4. (d) Record your observations in an appropriate table. You do not need to make conclusions on the presence or absence of each substance in the samples tested. Sample Observations Test for starch / Iodine test Test for glucose / Reducing sugar test Test for sucrose / Non-reducing sugar test S1 The mixture remained yellow-brown The mixture remained blue The mixture remained blue S2 The mixture turned blue-black The mixture remained blue The mixture remained blue S3 The mixture remained yellow-brown The mixture remained blue Brick-red ppt is formed S4 The mixture turned blue-black Brick-red ppt is formed Brown/Brick-red ppt is formed 1. Appropriate table layout (sample on leftmost column); 2. Appropriate column headings (heading for ‘sample/extract/plant extract’); 3. Observations (correct phrasing of observation with good details); R! ticks/crosses 4. Complete set of results + correct trend; [4] (e) Complete Table 1.3 to match the samples, S1, S2, S3 and S4, with each plant extract. Table 1.3 source of plant extract sample a root in winter S2 a root in spring S4 phloem sap from the stem in summer S3 phloem sap from the stem in winter S1 [1] [Total: 12]

6 Anglo-Chinese Junior College H2 9744 Paper 4 Preliminary Examina