HCI 2024 Prelim H2 Bio P3 Qn

© Hwa Chong Institution 2024 9744 H2 Biology / JC2 Preliminary Examinations / Paper 3 HWA CHONG INSTITUTION JC2 Preliminary Examinations Higher 2 CANDIDATE NAME CT GROUP 23S7 __ CENTRE NUMBER INDEX NUMBER BIOLOGY Paper 3 Long Structured and Free-response Questions Candidates answer on the Question Paper. No Additional Materials are required. 9744/03 10 September 2024 2 hours INSTRUCTIONS TO CANDIDATES There are four question booklets (I - IV) 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 pages of Booklets II, III and IV. Write in dark blue or black pen. You may use an HB pencil for any diagrams or graphs Section A Answer all questions in the spaces provided on the Question Paper. Section B Answer any one question 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 answer. This document consists of 20 printed pages. For Examiners' Use Section A 1 / 30 2 / 10 3 / 10 Section B 4 or 5 / 25 Final Mark

2 © Hwa Chong Institution 2024 9744 H2 Biology / JC2 Preliminary Examinations / Paper 3 SECTION A Answer all the questions in this section. QUESTION 1 Multistep signalling pathways control cellular functions through complex protein interactions. When some these pathways are dysregulated, it can lead to uncontrolled cell growth and cancer. (a) Outline the advantages of having such multistep pathways. [2] Chronic inflammation is known to contribute to cancer development. Researchers are examining how signalling molecules like interleukin-6 (IL6), a cytokine, is important for the body's response to infection and inflammation. Fig. 1.1 shows the IL6 signalling pathway. IL6 binds to its receptor, IL6R. The complex binds with gp130, which functions similarly to a receptor tyrosine kinase (RTK). The tyrosine kinase on gp130, JAK, activates downstream pathways that drive inflammation. gp130 IL6 IL6R STAT3 target genes that induce inflammation Fig. 1.1

3 © Hwa Chong Institution 2024 9744 H2 Biology / JC2 Preliminary Examinations / Paper 3 (b)(i) Explain why IL6 cannot act directly on the DNA in the nucleus. [2] (b)(ii) Based on your knowledge on RTKs and with reference to Fig. 1.1, explain how IL6 leads to a cellular response. [5] (b)(iii) STAT3 activation is regulated by negative feedback. When STAT3 activation is excessive, more SOCS3 protein is synthesised, leading to ubiquitination of gp130