2025 CJC H2Bio PE P3 (A)

NAME: ___________________________________________ CLASS: _________ INDEX: __________ CATHOLIC JUNIOR COLLEGE JC2 PRELIMINARY EXAMINATION Higher 2 BIOLOGY 9744/03 Paper 3 Long Structured and Free-Response Questions 16 September 2025 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 on all the work you hand in. Write in dark blue or black pen on both sides of the paper. [PILOT FRIXION ERASABLE PENS ARE NOT ALLOWED] You may use a soft pencil for any diagrams, graphs, or rough working. Do not use staples, paper clips, highlighters, glue, or correction fluid. Section A Answer all questions in the spaces provided on the Question Paper. Section B Answer any one question in this section. Write your answers in the writing 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. This document consists of 20 printed pages and 0 blank page. [Turn over For Examiner’s Use Section A 50 1 2 3 Section B 25 4 or 5 Total 75 Suggested Answers

2 2025 Prelim/ 9744/ 03 Section A Answer all the questions in this section. 1 Based on the statistics by World Health Organisation (WHO), cancer is a leading cause of death worldwide, accounting for nearly 10 million deaths in 2020, or nearly one in six deaths. Many causative factors, including chemical carcinogens may increase the chances of cancerous growth. (a) Name one chemical carcinogen. ……………………………………………………………………………………………………………. [1] 1. Benzo[a]pyrene / ethidium bromide / 5’-Bromouracil / AVP. Studies showed that individuals inheriting BRCA 1 gene that underwent loss-of-function mutation have an increased risk of developing breast and ovarian cancers. (b) Based on the information above, identify the type of gene BRCA 1 belongs to and justify your answer. ……………………………………………………………………………………………………………...... ……………………………………………………………………………………………………………...... ……………………………………………………………………………………………………………. [2] 1. Tumour suppressor genes 2. (The loss-of-function mutation of BRCA 1 increases the risk of developing breast and ovarian cancers implies that ) this gene codes for gene products that inhibit growth without the appropriate conditions (OWTTE).

3 2025 Prelim/ 9744/ 03 Mutations in another gene, BRCA 2, was shown to increase the risk of developing breast and ovarian cancers. Fig. 1.1 shows the percentage risk of developing these cancers in general populat