2026 CJC H2 Biology 9477 P2 QP

CATHOLIC JUNIOR COLLEGE JC2 PRELIM EXAMINATION Higher 2 CANDIDAT E NAME CLASS 2T INDEX NUMBE R BIOLOGY 9477/02 Paper 2 Structured Questions 31 st August 2026 2 hours Candidates answer on the Question Paper No Additional Materials are required READ THESE INSTRUCTIONS FIRST Write your name (as per NRIC), class, and index number 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 Total 90 1 [9] 2 [8] 3 [12] 4 [11] 5 [11] 6 [16] 7 [10] 8 [7] 9 [6]

2 This document consists of 19 printed pages and 1 blank page. [Turn over Answer all questions. 1 Fig. 1.1 shows an electron micrograph of a steroid-producing endocrine cell. Fig. 1.1 With reference to Fig. 1.1, (a) Identify organelles A and B . Organelle A ………………………………..….… Organelle B ……………………………………… [2] (b) Describe one structural feature of each organelle, A and B , and explain how each feature adapts the cell for its function in steroid hormone production. Organelle A ………………………………………………………………………………………………….. ………………………………………………………………………………………………………………….. . ………………………………………………………………………………………………………………….. . 9477 H2 Biology 2026 JC2 Preliminary Examination Paper 2

3 ………………………………………………………………………………………………………………….. . Organelle B ………………………………………………………………………………………………….. ………………………………………………………………………………………………………………….. . ………………………………………………………………………………………………………………….. . ………………………………………………………………………………………………………………...[4 ] (c) Explain the significance of the close proximity between organelle A and organelle B during the synthesis of steroid hormones. ………………………………………………………………………………………………………………….. ………………………………………………………………………………………………………………. [1] (d) Steroid hormones are synthesised on demand and pass out of endocrine cells immediately upon production. Explain why the physical properties of steroid molecules allow them to leave the cell by simple diffusion, and why they cannot be released by exocytosis. ………………………………………………………………………………………………………………….. ………………………………………………………………………………………………………………….. ………………………………………………………………………………………………………………….. ………………………………………………………………………………………………………………. [2] [Total: 9] 9477 H2 Biology 2026 JC2 Preliminary Examination Paper 2

4 2 Researchers isolated a sucrase enzyme from the bacterium Bacillus subtilis. They immobilised the enzyme in alginate beads. The researchers investigated the effects of pH on the activity of the immobilised sucrase compared with the activity of the same enzyme free in solution. The results are shown on Fig. 2.1. Fig. 2.1 (a) With reference to Fig. 2.1 (i) state the optimum pH for both the immobilised sucrase and free sucrase. …………………………………………………………………………………………………………. [1] 9477 H2 Biology 2026 JC2 Preliminary Examination Paper 2

5 (ii) compare the effect of increasing pH above 5.5 on the percentage of maximum enzyme activity for immobilised sucrase and free sucrase. …………………………………………………………………………………………………………….. …………………………………………………………………………………………………………….. …………………………………………………………………………………………………………….. …………………………………………………………………………………………………………. [2] 9477 H2 Biology 2026 JC2 Preliminary Examination Paper 2

6 (b) In order to measure enzyme activity at each pH, the researchers measured the rate of product formation using an excess concentration of sucrose solution over a fixed duration. With reference to the molecular mechanism of enzymes, explain why maintaining an excess substrate concentration was essential to ensure valid results when comparing enzyme activity across different pH values. ………………………………………………………………………………………………………………….. ………………………………………………………………………………………………………………….. ………………………………………………………………………………………………………………….. ………………………………………………………………………………………………………………….. ………………………………………………………………………………………………………………….. ………………………………………………………………………………………………………………. [3] (c) In food manufacturing, the enzyme sucrase is physically trapped within insoluble calcium alginate beads packed into a continuous-flow column reactor to hydrolyse sucrose. Suggest two economic advantages of using immobilised sucrase rather than sucrase solution in large-scale industrial bioreactors. ………………………………………………………………………………………………………………….. ………………………………………………………………………………………………………………….. ………………………………………………………………………………………………………………….. ………………………………………………………………………………………………………………. [2] [Total: 8] 9477 H2 Biology 2026 JC2 Preliminary Examination Paper 2

7 3 Down Syndrome-associated Acute Megakaryoblastic Leukaemia (DS-AMKL) is a type of blood cancer. Individuals with Trisomy 21 have a significantly higher risk of developing DS-AMKL, which typically develops through a multi-step process involving an initial mutation in the GATA1 gene, followed by secondary mutations in proto-oncogenes and tumour suppressor genes. Fig. 3.1 shows a portion of the wild-type and mutant mRNA sequences from exon 2 of the GATA1 gene. Codon position : 1 2 3 4 5 Wild-type mRNA : 5' - AUG GAG UUA ACG GUG… -3' Mutant mRNA : 5' - AUG GAU UAA CGG UG… -3' Fig. 3.1 (a) With reference to Fig. 3.1, (i) name the type of gene mutation that occurred in the GATA1 gene. …………………………………………………………………………………………………………. [1] (ii) explain the effect of the gene mutation on the amino acid sequence and the resulting GATA1 protein. …………………………………………………………………………………………………………….. …………………………………………………………………………………………………………….. …………………………………………………………………………………………………………….. …………………………………………………………………………………………………………. [2] (b) Explain how non-disjunction during meiosis can give rise to an abnormal gamete that results