NYJC 2023 J2 Prelim Paper 4 Ans (For Sharing)

9744 / H2 Biology / 04 NANYANG JUNIOR COLLEGE PRELIMINARY EXAMINATIONS Higher 2 CANDIDATE NAME ANSWERS CLASS BIOLOGY 9744/04 Paper 4 Practical 24 August 2023 Candidates answer on the Question Paper Additional Materials: As listed in the Confidential Instructions 2 hour 30 minutes READ THESE INSTRUCTIONS FIRST Write your name and CT 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, highlighters, glue or correction fluid. DO NOT WRITE IN 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. Shift Laboratory 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. For Examiner’s Use 1 2 Total This document consists of 16 printed pages and 0 blank pages. [Turn over

9744 / H2 Biology / 04 2 Answer all the questions. 1 Some fruit contains large quantities of ascorbic acid (vitamin C). Ascorbic acid can be absorbed through the partially permeable wall of the gut. You will investigate the rate at which ascorbic acid from a 2 gdm–3 ascorbic acid solution diffuses across a partially permeable membrane. Dialysis (Visking) tubing acts as a partially permeable membrane. You are provided with the materials shown in Table 1.1. Table 1.1 labelled contents hazard quantity A 2 gdm-3 ascorbic acid solution irritant 80cm3 W distilled water none 200cm3 D dialysis tubing in distilled water none 20cm I iodine solution irritant 25cm3 S starch solution none 20cm3 It is recommended that you wear suitable eye protection. You will need to: • allow ascorbic acid to diffuse out of the dialysis tubing into the distilled water surrounding the dialysis tubing • estimate the concentration of ascorbic acid that has diffused out of the dialysis tubing. Carry out step 1 to step 27. step 1 Tie a knot in the dialysis tubing as close as possible to one end, so that the end is sealed. step 2 To open the other end, wet the dialysis tubing and rub the tubing gently between your fingers and thumb. step 3 Put 10 cm 3 of ascorbic acid solution A into the open end of the dialysis tubing. step 4 Rinse the outside of the dialysis tubing by dipping it in the container of water labelled D. step 5 Carefully place the filled dialysis tubing bag into the large test-tube and secure position using an elastic band, as shown in Fig. 1.1.

9744 / H2 Biology / 04 3 Fig. 1.1 You will need to fill the large test -tube with