2026 RI H2 Biology Prelims P2 Questions

© RI 2026 Preliminary Examination 9477/02 [Turn over RAFFLES INSTITUTION 2026 Year 6 Preliminary Examination Higher 2 BIOLOGY 9477/02 Paper 2 Structured Questions 16th September 2026 2 hours Candidates answer on the Question Paper. No Additional Materials are required. READ THESE INSTRUCTIONS FIRST Write your index number, CT group & name in the spaces at the top of this page. 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 The number of marks is given in brackets [ ] at the end of each question or part question. FOR EXAMINER’S USE Q1 Q2 Q3 Q4 Q5 Q6 10 10 11 12 13 9 Q7 Q8 Q9 TOTAL 8 12 5 90 This document consists of 23 printed pages and 1 blank page. CIVICS GROUP CANDIDATE NAME INDEX NUMBER 6 S 0 3 2 2 6

2 © RI 2026 Preliminary Examination 9477/02 For Examiner’s Use [Turn over 1 Some enzymes digest protein by hydrolysing the peptide bonds between amino acids. The extent to which a protein is digested is called the degree of hydrolysis (DH). The DH value may be calculated from the equation: DH = 100 X number of peptide bonds hydrolysed ___________________________________ total number of peptide bonds present (a) A protein made up of 151 amino acids was digested. The DH value of the digested protein was 18%. Calculate the number of peptide bonds that have been hydrolysed. [1] (b) The enzyme trypsin hydrolyses proteins into short peptide chains. Fig. 1.1 illustrates the mode of action of trypsin. Fig. 1.1 Raffles Institution Internal Examination

3 © RI 2026 Preliminary Examination 9477/02 [Turn over For Examiner’s Use (i) With reference to Fig. 1.1, explain the mode of action of trypsin. ……………………………………………………………….…………………………..………… ……………………………………………………………….…………………………..………… ……………………………………………………………….…………………………..………… ……………………………………………………………….……………………………..……… ……………………………………………………………….…………………………..………… ……………………………………………………………….…………………………..………… ……………………………………………………………….……………………………..……… ……………………………………………………………….……………………………..……… ……………………………………………………………………………………………..…….[4] (ii) Trypsin can hydrolyse more than one type of protein. Explain why it is possible for trypsin to act on different types of protein. ……………………………………………………………….……………………………..……… ……………………………………………………………………………………………..…….[1]

4 © RI 2026 Preliminary Examination 9477/02 For Examiner’s Use [Turn over (c) Proteases are present in some washing powders used for cleaning clothes. They digest protein- based stains such as those caused by blood, egg and sweat. Fig 1.2 shows the effect of pH on the activities of trypsin and pepsin. Fig. 1.2 Two identical samples of a protein, A and B, were each mixed with an excess of trypsin and left for the same length of time. Sample A was kept at pH 8, and sample B was kept at pH 6. All other conditions were kept the same and under optimal conditions. Predict and explain how the degree of hydrolysis (DH) of sample B would compare with sample A. ……………………………………………………………………………………………………………... ……………………………………………………………………………………………………………... ……………………………………………………………………………………………………………... ……………………………………………………………………………………………………………... ……………………………………………………………………………………………………………... ……………………………………………………………………………………………………………... ……………………………………………………………………………………………………………... …………………………………………………………………………………………………………..[4] 6 4 100 80 60 40 20 pH relative activity / % pepsin trypsin 0 2 8 10 12 14 0

5 © RI 2026 Preliminary Examination 9477/02 [Turn over For Examiner’s Use [Total: 10] 2 Fig. 2.1 is a transmission electron micrograph of a cell from the stem of the sago pondweed, Stuckenia pectinata. Fig. 2.1 (a) State the evidence from Fig. 2.1 that shows that the cell is from the stem and not from the mesophyll of a leaf of S. pectinata. …………………………………………………………………………………………………………..[1] (b) Identify structure C and explain why it is so darkly stained. ……………………………………………………………………………………………………………... ……………………………………………………………………………………………………………... …………………………………………………………………………………………………………..[2] (c) (i) From Fig. 2.1, name and identify (using letters A to G) a membrane that carries out active transport. name of membrane: ..……………………………………………….………………………….. letter on Fig. 2.1: ……………………………………………………………….……………..[1] cellulose cell wall air space G F A B C D E magnification x2500

6 © RI 2026 Preliminary Examination 9477/02 For Examiner’s Use [Turn over (ii) Describe active transport. ……………………………………………………………….…………………………..………… ……………………………………………………………….……………………………..……… ……………………………………………………………….……………………………..……… ……………………………………………………………………………………………..…….[2] (d) Fig. 2.2 shows the movement of vesicles within a plant cell during the development of a vacuole. Fig. 2.2 (i) Name the process that is occurring at X. ……………………………………………………………………………………………..…….[1] cell surface membrane Golgi body rough endoplasmic reticulum vacuole multi-vesicular body key protein folded correctly protein not folded correctly

7 © RI 2026 Preliminary Examination 9477/02 [Turn over For Examiner’s Use (ii) Some of the vesicles formed by the Golgi body pass to the vacuole. Amongst these vesicles, some contain proteins that have folded correctly while others contain proteins that have not folded correctly. The proteins that have not folded correctly pass to the vacuole where they are broken down. Waste management in plants involves two distinct pathways : the ubiquitin-proteasome pathway which operate exclusively in the cytosol and the nucleus, and the vacuolar pathway which is described above. Explain how proteins that have not folded correctly are broken down in the vacuole. ……………………………………………………………….…………………………..………… ……………………………………………………………….…………………………..………… ……………………………………………………………….……………………………..……… ……………………………………………………………….……………………………..……… ……………………………………………………………………………………………..…….[2] (e) Small vacuoles in S. pectinata may have roles similar to lysosomes in animal cells. State the role of lysosomes in animal cells, apart from defence against pathogens. …………………………………………………………………………………………………………..[1] [Total: 10]

8 © RI 2026 Preliminary Examination 9477/02 For Examiner’s Use [Turn over 3 Leber congenital amaurosis (LCA) is an inherited eye disease. In LCA, photoreceptor cells in the retina die at an early age. This causes impaired vision that may progress to blindness. One form of LCA is caused by a mutation in the CEP290 gene. The CEP290 gene codes for the CEP290 protein,