2025 ASRJC H2 Biology Prelims Paper 4_QP

ASRJC BIOLOGY DEPT 9744/2025/J2PRELIM/P4 H2 ANDERSON SERANGOON JUNIOR COLLEGE HIGHER 2 2025 JC2 PRELIMINARY EXAMINATION CANDIDATE NAME CLASS 2 5 / INDEX NUMBER BIOLOGY 9744/04 Paper 4 Practical Candidates answer on the Question Paper. Additional Materials: As listed in the Confidential Instructions. 28 August 2025 Thursday 2 hours 30 minutes READ THESE INSTRUCTIONS FIRST Write your name and class 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. This document consists of 23 printed pages and 1 blank page. Shift Laboratory For Examiner’s Use 1 / 28 2 / 13 3 / 14 Total / 55 %

2 ASRJC BIOLOGY DEPT 9744/2025/J2PRELIM/P4 Answer all questions. 1 Amylase is an enzyme that catalyses the hydrolysis of starch to maltose. You will investigate the effect of the concentration of amylase on the time taken to completely hydrolyse starch to maltose. Iodine solution turns from an orange-brown colour to a blue-black when starch is present. The course of the reaction can be monitored by sampling at intervals and using iodine solution to test for the presence of starch. The end -point is when all the starch has been hydrolysed by amylase. At the end-point, the colour of the iodine solution may be slightly different compared to the colour of the original iodine solution and there may be some specks of blue -black. These specks of blue-black can be ignored. (a) Describe and explain how reducing the concentration of amylase is expected to affect the time taken to reach end-point. …………………………………………………………...……….…………………………………… ………………………………………...………………………….…………………………………… …………………..…………………….……….……………………………………………………… …………………………..……………….………………….………………………………………… ………………………………………………………………………………………………………[2] You are provided with: • 200 international units dm-3 (U dm-3) amylase solution A, in a container labelled A • distilled water W, in a container labelled W • starch solution S, in a container labelled S • iodine solution in a container labelled iodine. Amylase solution A is an irritant and iodine solution is a stain. Suitable eye pro