2025 RVHS H2 Biology Prelims Paper 4 QP

RIVER VALLEY HIGH SCHOOL JC 2 PRELIMINARY EXAMINATION CANDIDATE NAME CENTRE NUMBER S CLASS 24J INDEX NUMBER H2 BIOLOGY 9744/04 Paper 4 Practical 28 Aug 2025 Candidates answer on the Question Paper. 2 hours 30 minutes Additional Materials: As listed in the Confidential Instructions. READ THESE INSTRUCTIONS FIRST Write your Centre number, index number, class and name 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. DO NOT WRITE ON ANY BARCODES. 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 Examiner’s Use 1 2 Total This document consists of 16 printed pages and 2 blank pages.

2 River Valley High School 2025 JC2 Preliminary Examination H2 Biology 9744/04 Answer all questions. 1 A farmer claimed that the carrots he grew contained a high sugar concentration and that the sugars were more effectively taken up by the gut as compared to standard carrot breeds. Carrots generally contain different types of sugars, with sucrose and simple sugars being the most abundant. In this experiment, you will investigate the validity of his claims. You are required to: • perform serial dilution to obtain different concentrations of S • estimate the sugar concentration in X • determine if sugars in the farmer-grown carrots are more effectively taken up. You are provided with: • 100 cm 3 of 1.0 mol dm -3 sugar solution obtained from standard carrot breed s, in a beaker labelled S • 50 cm3 of farmer-grown carrot extract, in a beaker labelled X • Visking tubing, in a beaker of distilled water labelled D • distilled water, in a beaker labelled W. Before starting the investigation, read through steps 1-24 and prepare a table in (c).

3 River Valley High School 2025 JC2 Preliminary Examination H2 Biology 9744/04 Proceed as follows. 1 You are required to make a proportional dilution of 1.0 mol dm -3 sugar solution S, to reduce its concentration by five-fold between each successive dilution. After the serial dilution is completed, you will need to have at least 40 cm3 of each concentration available for use. (a) Complete Fig. 1.1 to show how you will dilute S. For each specimen tube: • state, under the tube, the volume and concentration of the solution S in the tube that will be available for use in the investigation, after the serial dilution has been completed • use one arrow, with a label above the tube, to show the volume and concentration of S added to prepare the solution in the tube • use another arrow, with a label above the tube, to show the volume of distilled water, W, added to prepare the concentration of S in the tube. [3] Fig. 1.1 ___ cm3 1.0 mol dm-3 S ____ cm3 1.0 mol dm-3 S ___cm3 ___ mol dm-3 S ____ cm3 ____mol dm-3 S 0 cm3 of W ___cm3 of W ____ cm3 ____mol dm-3 S ____ cm3 ____mol dm-3 S

4 River Valley High School 2025 JC2 Preliminary Examination H2 Biology 9744/04 2 Using hot water and tap water, adjust around 300 cm3 of water in the beaker labelled water-bath to 60 °C. You do not need to maintain this temperature. 3 Label five boiling tubes with the concentrations diluted in (a) and with X. 4 Put 12 cm3 of distilled water W into each boiling tube and place them in the water bath. 5 Remove a Visking tubing from beaker D. 6 Tie a knot in the Visking tubing as close as possible to one end, so that the end is sealed. 7 To open the other end, rub the tubing gently between your fingers and thumb. 8 Put 6 cm3 of 1.0 mol dm-3 S into the open end of the Visking tubing. 9 Rinse the outside of the Visking tubing with distilled water and wipe dry with a paper towel. 10 Repeat steps 5 to 9 for the other concentrations diluted in (a) and for X. 11 Put the filled Visking tubings into the respective labelled boiling tubes at the same time. 12 Ensure that the content in the Visking tubing is fully submerged in W. You may need to fold the tubing to do so. Leave the apparatus for 10 minutes. Use this time to continue with (b) and step 13. The sugar concentration in the carrot extract can be estimated using the semi -quantitative results of the Benedict’s test. The amount of precipitate settled at the bottom of the test-tube may be used to estimate the sugar content. (b) Describe how Benedict’s test may be conducted to more reliably estimate the total sugar content in X. [4]

5 River Valley High School 2025 JC2 Preliminary Examination H2 Biology 9744/04 The results of Benedict’s test on the concentrations diluted in (a) and on X are provided in the test-tube rack and labelled B1, B2, B3, B4 and BX, where B1 is the highest concentration and B4 is the lowest. 13 Record the amount of precipitate in the table in (c). You may use the terms ‘large’, ‘moderate’, ‘small’ and ‘trace’ to describe the amount of precipitate observed. 14 After 10 minutes, remove all Visking tubing from the boiling tubes at the same time. Place the Visking tubing in the beaker labelled “waste”. 15 Label the test-tubes (marked 3 cm from the bottom) with the concentrations diluted in (a). 16 Using the measuring cylinder, put 10 cm3 of the solution remaining in the boiling tube labelled “1.0 mol dm-3 S” into the appropriately labelled test-tube. 17 Repeat step 16 with each of the other diluted sugar concentrations. 18 Put 1 cm3 of the blue dye, M, into the boiling tube labelled X. Swirl the contents to mix M with the solution. The blue dye may not mix in completely. This will not affect the results. 19 Use a pipette to remove a sample of the blue solution in boiling tube X. Throughout steps 20 to 22, the pipette must be held still so that its position does not change. Drops can then be released at the mark and observed without disturbing the solution as shown in Fig. 1.2. Fig. 1.2 20 Put the end of the pipette into the small test -tube labelled “1.0 mol dm -3 S”. The end of the pipette should be level with the mark on the small test-tube 21 Keeping the end of the pipette as still as possible, release a drop of the blue solution from the pipette. 22 Observe the direction of movement of the drop of blue solution. You may use the terms ‘move up’, ‘move down’ and ‘remains at the same level’ to describe the movement. This movement occurs w hen two solutions of different densities are added to one another without mixing, the denser solution will sink to the bottom and the less dense solution will rise to the top. 23 Record your observations in (c). 24 Repeat steps 19 to 23 for the other concentrations of sugar. 3 cm one drop of X

6 River Valley High School 2025 JC2 Preliminary Examination H2 Biology 9744/04 (c) Record your results in a suitable table in the space below. [3] (d) Using the data from your table in (c), (i) estimate the sugar concentration in X. [1] (ii) explain if the sugar in the farmer-grown carrot is absorbed more effectively than the standard carrot breed. [2] (e) Explain why the results on the effectiveness of sugar absorption in (c) may be different if the investigation was conducted using gut epithelial cells. [2]

7 River Valley High School 2025 JC2 Preliminary Examination H2 Biology 9744/04 (f) Complete Table