2024 ASRJC H2 Bio P2 MS

ASRJC BIOLOGY DEPT 9744//2024/J2PRELIM/P2 [Turn over H2 ANDERSON SERANGOON JUNIOR COLLEGE HIGHER 2 ANSWERS 2024 JC2 PRELIMINARY EXAMINATIONS CANDIDATE NAME CLASS INDEX NUMBER BIOLOGY 9744/02 PAPER 2 SHORT STRUCTURED QUESTIONS Candidates answer on the Question Paper. No Additional Materials are required. 12 SEPTEMBER 2024 THURSDAY 2 HOURS READ THESE INSTRUCTIONS FIRST Write your name and class on all the work you hand in. Write in dark blue or black pen. You may use an HB pencil for any diagrams or graph Do not use paper clips, highlighters, glue or correction fluid. Answer all questions. 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 13 printed pages and 1 blank page For Examiner’s Use 1 / 7 2 / 10 3 / 11 4 / 11 5 / 12 6 / 10 7 / 10 8 / 8 9 / 12 10 / 4 11 / 5 Total /100

2 ASRJC BIOLOGY DEPT 9744//2024/J2PRELIM//P2 Answer all the questions. 1 Starch and cellulose are carbohydrates that are found in most plants. (a) Compare between structures of amylose and amylopectin of starch. Similarity (max 1) 1. Both are composed of α-glucose monomers. 2. Both contain α(1,4) glycosidic bonds between monomers. Difference (max 1) 1. Amylopectin contain α(1,4) glycosidic bonds and α(1,6) glycosidic bonds while amylose only contain α(1,4) glycosidic bonds. (A: amylopectin contain α(1,6) glycosidic bonds while amylose do not.) 2. Amylopectin is branched while amylose is unbranched. [2] (b) Juices that are extracted commercially from fruits can be made less cloudy by the breakdown of the cellulose cell wall using the enzyme cellulase. In the space below, show how the bonds in a short section of cellulose that is made up of three monomers may be broken by cellulase. Add appropriate labels to your drawing. 1. Structures of cellulose with indication of ‘continuity’ for polymer + correct rotation + correctly labelled glycosidic bond 2. Correct structure of 3 -glucose monomer correctly drawn including H 3. Type of reaction labelled (hydrolysis) + 2 water molecules indicated as reagents [3]

3 ASRJC BIOLOGY DEPT 9744//2024/J2PRELIM/P2