2026 HCI 9477 H2 Bio Prelim P2 QP

HWA CHONG INSTITUTION JC2 Preliminary Examinations Higher 2 CANDIDATE NAME CT GROUP 25S7 __ CENTRE NUMBER S INDEX NUMBER BIOLOGY Paper 2 Structured Questions Candidates answer on the Question Paper. No Additional Materials are required. 9477/02 27 August 2026 2 hours READ THESE INSTRUCTIONS FIRST There are five question booklets ( I - V ) to this paper. Write your name , CT group , Centre number and index number in the spaces provided at the top of this cover page and on the lines provided at the top of the cover page of Booklets II, III, IV and V . 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. There are ten questions. 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. You are reminded of the need for good English and clear presentation in your answers. This document consists of 26 printed pages. © Hwa Chong Institution 2026 9477 H2 Biology / JC2 Preliminary Examinations / Paper 2 For Examiners' Use 1 / 8 2 / 9 3 / 10 4 / 9 5 / 11 6 / 10 7 / 8 8 / 10 9 / 8 10 / 7 Total / 90

2 QUESTION 1 (a) Rubredoxin is a protein found in bacteria. It contains around 50 amino acids. One iron ion is bound by the sulphur atoms of four cysteine amino acids. The structure of rubredoxin is shown in Fig. 1.1. Fig. 1.1 (a) (i) Rubredoxin and haemoglobin are classified as conjugated proteins . Use Fig. 1.1 to explain what is meant by the term conjugated protein. [2] (a) (ii) Rubredoxin and haemoglobin have different secondary and tertiary structures. Using the information provided about rubredoxin, state two other differences between the structures of rubredoxin and haemoglobin. difference 1 difference 2 [2] © Hwa Chong Institution 2026 9477 H2 Biology / JC2 Preliminary Examinations / Paper 2

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4 (b) Ferritin is a protein that is used to regulate iron levels within plant tissues. It is a large spherical structure which can hold many iron ions (Fe 3+ ) at its centre. Iron can be toxic to plant tissues. Ferritin prevents the build-up of iron. Fig. 1.2 shows the internal structure of ferritin. Fig. 1.2 (b) (i) Ferritin molecules can hold 4500 Fe 3+ ions in the inner sphere. It is thought that the Fe 3+ ions are unable to occupy the total available volume of the inner sphere because other molecules are present in the inner sphere. The volume of the inner sphere of the ferritin molecule is 268 nm 3 . The volume of an Fe 3+ ion is 9.04 × 10 -4 nm 3 . Calculate the volume of the inner sphere not occupied by Fe 3+ ions. volume = ……………………………….nm 3 [2] © Hwa Chong Institution 2026 9477 H2 Biology / JC2 Preliminary Examinations / Paper 2

5 (b) (ii) Explain how hydrophilic and hydrophobic interactions contribute to the spherical shape of ferritin. [2] [Total: 8] © Hwa Chong Institution 2026 9477 H2 Biology / JC2 Preliminary Examinations / Paper 2

6 QUESTION 2 Estrogen receptors (ER) are ligand-inducible transcription factors that regulate expression of many genes such as those involved in growth, proliferation and cell cycle progression. Fig. 2.1 is a diagram showing the interactions between ER, its ligand estrogen, and components within a cell of breast tissue. RNA polymerase is not shown. Legend: : estrogen : long stretch of DNA M1 and M2 : mediator proteins G : general transcription factor ERE : estrogen response element Fig. 2.1 © Hwa Chong Institution 2026 9477 H2 Biology / JC2 Preliminary Examinations / Paper 2

7 (a) Describe the stages A , B and C . Stage A : [2] Stage B : [1] Stage C : [2] © Hwa Chong Institution 2026 9477 H2 Biology / JC2 Preliminary Examinations / Paper 2

8 Estrogen receptors are over-expressed in around 70% of breast cancer cases. Research into the treatment of metastatic breast cancer focuses on the use of drugs such as selective estrogen-receptor modulator (SERM) and estrogen receptor downregulator (ERDR), as shown in Table 2.1. Table 2.1 drug ER-drug interaction presence of drug-receptor complex in the nucleus effect of drug on the expression of target gene SERM ✔ ERDR /g0 no gene expression (b) With reference to Table 2.1, (b) (i) explain how SERMs can be used in the treatment of breast cancer. [2] (b) (ii) suggest why ERDRs might be more effective than SERMs. [2] © Hwa Chong Institution 2026 9477 H2 Biology / JC2 Preliminary Examinations / Paper 2

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10 QUESTION 3 Fig. 3.1 is an electron micrograph showing influenza viruses infecting an epithelial cell of the human respiratory tract. Fig. 3.1 (a) With reference to Fig. 3.1, describe how an influenza virus enters the epithelial cell of the human respiratory tract. [3] © Hwa Chong Institution 2026 9477 H2 Biology / JC2 Preliminary Examinations / Paper 2