2025 JPJC H2Bio PE P3 (A)

9744 / 03 [Turn over NAME : CLASS : JURONG PIONEER JUNIOR COLLEGE JC2 Preliminary Examination 2025 BIOLOGY Higher 2 9744/03 15 September 2025 Paper 3 Long Structured and Free-response Questions 2 hours Additional Materials: Answer Booklet READ THESE INSTRUCTIONS FIRST Write your class and 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. Section A Answer all questions in the spaces provided on the Question Paper. Section B Answer any one question on the separate Answer Booklet provided. 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 1 2 3 Section B Total This document consists of 19 printed pages and 1 blank page.

2 JPJC/JC2 H2 Biology/PE/2025 Section A Answer all questions. 1 Following a body injury, bone marrow stem cells migrate to the site of damage, where they undergo cell differentiation to replace damaged cells. In eukaryotes, cell growth and division are tightly regulated processes to ensure proper repair. Cells will only pass specific checkpoints in the cell cycle if certain conditions are met, one of which is the presence of growth factors. Fig. 1.1 shows how this differentiation occurs. Fig. 1.1 (a) (i) Outline how SCFR is produced and transported to the cell surface. ................................ ................................ ................................ ................... [4] 1. gene/c-KIT undergoes transcription in nucleus (to form pre-mRNA) ; 2. post-transcriptional modification s take place [A! RNA splicing, 5’ capping, 3’ polyadenylation (any 1)] to form mature mRNA ; 3. mRNA is translated at ribosomes on rough endoplasmic reticulum (rER) ; 4. biochemical modifications take place in rER ; 5. budding occurs with SCFR/receptor embedded in vesicle membrane / in vesicle ; 6. SCFR/receptor enter Golgi body to be further modified, sorted and packaged ; 7. budding occurs with SCFR/receptor embedded in vesicle membrane ; 8. (compulsory) vesicles with SCFR embedded in vesicle membrane move to and fuse with cell surface membrane (of stem cells) ; MP5&7, award once (ii) Suggest how SCFR is destroyed by a lysosome. ................................ ................................ ................................ ................... [1] 1. The vesicle fuses/binds with a lysosome , the h ydrolytic enzymes break down/hydrolyse/digest SCFR ; A! Accept protease

3 JPJC/JC2 H2 Biology/PE/2025 [Turn over Fig. 1.2 shows an example of how signals from growth factors are transduced to result in cell growth an