2022 HCI JC2 H2 Biology Prelims Paper 4 QP

© Hwa Chong Institution 2022 9744 H2 Biology / JC2 Preliminary Examinations / Paper 4 HWA CHONG INSTITUTION JC2 Preliminary Examinations Higher 2 CANDIDATE NAME CT GROUP 21S7 __ CENTRE NUMBER INDEX NUMBER BIOLOGY Paper 4 Practical No additional materials are required. 9744/04 31 August 2022 2 hours 30 minutes INSTRUCTIONS TO CANDIDATES There are three questions to this paper. Write your name, CT group, Centre number and index number in the spaces provided at the top of this cover page. Answer all questions in the spaces provided on the question paper. INFORMATION FOR CANDIDATES 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. The number of marks is given in brackets [ ] at the end of each question or part question. You are reminded of the need for good English and clear presentation in your answers. This document consists of 17 printed pages. Shift Laboratory For Examiners' Use 1 / 20 2 / 15 3 / 20 Total / 55

2 © Hwa Chong Institution 2022 9744 H2 Biology / JC2 Preliminary Examinations / Paper 4 QUESTION 1 Cheese-making is a process that concentrates protein, fat and other nutrients from milk. This process involves coagulating the casein protein in milk. Coagulation of milk occurs when the protein and lipid molecules in milk aggregate together forming a solid substance that is separated from the liquid component. Coagulation of milk can be caused by acidification of milk, the action of an enzyme (such as rennin), or a combination of the two. It has been found that t he usage of fruit extracts as a commercially- produced milk coagulant can increase the flavour and texture of the final cheese. You are required to:  make and record observations on the coagulation of milk by acid and rennin,  investigate the relative effective ness of acid and rennin in milk coagulation by measuring the time taken for milk coagulation to occur,  determine whether a fruit extract that is often used to make commercial coagulants contain acids, rennin, or both, as its active ingredient. You are provided with:  one slice of pineapple P, in a plastic bag,  diluted hydrochloric acid solution, in a container labelled H,  diluted rennin enzyme, in a container labelled E,  milk, in a container labelled M. Diluted hydrochloric acid H is corrosive. Suitable eye protection and gloves should be worn. If H comes into contact with your skin, wash off immediately under tap water. Care should be taken when using hot water. Proceed as follows. The coagulation of M by H can be observed using the following steps: 1 Add 5.0 cm3 of M to a test-tube. 2 Add 1.0 cm3 of H to the M in