ASRJC 2024 H2 Prelims P4 (A)

ASRJC BIOLOGY DEPT 9744//2024/J2PRELIM/P4 CANDIDATE NAME I BIOLOGY 9744/04 Paper 4 Practical 28 August 2024 Wednesday Candidates answer on the Question Paper. 2 hours 30 minutes Additional Materials: As listed in the Confidential Instructions. 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. Shift Laboratory For Examiner’s Use 1 2 3 Total 55 H2 ANDERSON SERANGOON JUNIOR COLLEGE HIGHER 2 CLASS INDEX NUMBER CLASS

2 ASRJC BIOLOGY DEPT 9744//2024/J2PRELIM/P4 This document consists of 21 printed pages and 3 blank pages. Answer all questions. 1 Bromelain is a proteolytic enzyme, which catalyses the hydrolysis of proteins into amino acid s. This enzyme can be found in fruits, such as pineapple. Gelatin contains structural proteins derived from animal tissues high in collagen. After dissolving in warm water, it sets into a gel-like structure upon cooling. The action of bromelain on gelatin gel results in liquification of the gel. You will investigate the effect of different concentrations of pineapple bromelain on gelatin breakdown. You are required to: • make five boiling tubes of gelatin gel • obtain pineapple juice extract using the pineapple sample provided • prepare a range of pineapple bromelain concentrations • add each concentration of pineapple bromelain solution into a boiling tube of gelatin gel • measure volume of liquified gelatin after 10 minutes of incubation. You are provided with: • 1 pineapple sample of a fixed mass, in a petri dish labelled A • 100.0 cm3 distilled water W, in a container labelled W • 3.0 g gelatin powder, in a specimen tube labelled G. Read steps 1- 6. Proceed as follows. 1 Using the container labelled hot water, collect approximately 100 cm3 of hot water from where it is provided in the laboratory. 2 Add all of the gelatin powder in a specimen tube labelled G into a beaker labelled X. Pour 75.0 cm3 of hot water directly into beaker X. 3 Use a gl