2024 TJC H2 Bio P3 QP

1 [TURN OVER READ THESE INSTRUCTIONS FIRST Write your Center number, index number 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. DO NOT WRITE IN ANY BARCODES. Section A Answer all questions in the spaces provided on the Question Paper. Section B Answer any one question in 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 any working or if you do not use appropriate units . The number of marks is given in the brackets [ ] at the end of each question or part question. TEMASEK JUNIOR COLLEGE 2024 JC2 PRELIMINARY EXAMINATION Higher 2 CANDIDATE NAME CENTRE NUMBER S INDEX NUMBER BIOLOGY 9744/03 Paper 3 Long Structured and Free Response Questions 9 SEPTEMBER 2024 2 hours Candidates answer on the Question Paper. No Additional Materials are required. For Examiner’s Use 1 / 28 2 / 11 3 / 11 4 / 5 / 25 This document consists of 25 printed pages and 3 blank pages.

2 Section A Answer all questions in this section. 1 Tuberculosis (TB) is an infectious disease caused by the bacterium. (a) Define the term infectious disease. …………………….………………………………………………………………………………………… .……………….…..……………………………………………………………………………………… [1] (b) State the name of the pathogenic organism which causes TB and d escribe its mode of transmission. Name of organism .……………………………………………………………………………….…… [1] Mode of transmission …………………………………………………………………………………….. …………………….………………………………………………………………………………………… .……………….…..……………………………………………………………………………………… [1] (c) One example of a defence mechanism against pathogens in the lun gs involves the action of macrophages. (i) State the location in the body where macrophages are formed. .……………….…..………………………………………………………………………….…… [1] (ii) Outline the mode of action of a macrophage. ……………………..…………………….…………………………………………………………… ……………………..…………………….…………………………………………………………… ……………………..…………………….…………………………………………………………… ……………………..…………………….…………………………………………………………… …………………………….……………….…..……………….………………………………… [2] (iii) It is sometimes possible for the pathogenic bacteria to survive within macrophages. Suggest one way in which these pathogenic bacteria may survive within a macrophage. ……………………..…………………….…………………………………………………………… …………………………….……………….…..……………….………………………………… [1]

3 [TURN OVER (iv) The TB bacterium has many operons in its DNA. Suggest one advantage to the bacterial cell in having operons. ……………………..…………………….…………………………………………………………… ……………………..…………………….…………………………………………………………… …………………………….……………….…..……………….………………………………… [1] Table 1.1 shows recent information about TB cases reported during one year in six different countries. Table 1.1 country region number of cases number of cases per 100 000 population Germany Europe 4000 5 India Asia 2 300 000 185 Japan Asia 27 000 21 South Africa Africa 490 000 981 Swaziland Africa 15 000 1287 United Kingdom Europe 7900 13 (d) With reference to Table 1.1, explain the advantage of calculati ng the number of cases of TB per 100 000 population rather than stating the number of cases alone. …………….….…………………………………………………………………………………………….. …………….….…………………………………………………………………………………………….. …………….….…………………………………………………………………………………………….. …………………….………………………………………………………………………………………… .……………….…..……………………………………………………………………………………… [2] Antibiotics are prescribed to people who have HIV for the treat ment of secondary infections such as bacterial infections. (e) Explain why antibiotics are prescribed to treat secondary infections, but not for HIV infection. …………….….…………………………………………………………………………………………….. …………….….…………………………………………………………………………………………….. …………….….…………………………………………………………………………………………….. …………………….………………………………………………………………………………………… .……………….…..……………………………………………………………………………………… [2]

4 Antibiotic rifampicin is observed to bind tightly to RNA polymerase molecule close to its active site. This affects the activity of the enzyme during the synthesis of RNAs, involving the action of RNA polymerase. (f) Suggest two ways in which rifampicin can affect the activity of RNA polymerase. …………….….…………………………………………………………………………………………….. …………….….…………………………………………………………………………………………….. …………….….…………………………………………………………………………………………….. …………………….………………………………………………………………………………………… .……………….…..……………………………………………………………………………………… [2]

5 [TURN OVER Question 1 continues on page 6.

6 (g) RNA polymerase is composed of fiv e different polypeptides. Gene rpoB codes for one of these polypeptides known as the β-subunit.  One or more mutations in a specific region of rpoB gene result in strains of TB bacteria that are resistant to rifampicin.  In these strains, mutations often occur in two DNA triplets, i n positions 526 and 531. Table 1.2 summarises the results of an investigation into seven rifampicin-resistant strains, A to G, that have amino acid changes for positions 526 and 531. Table 1.2 includes:  the change in the mRNA codon for position 526 or position 531  the amino acid change that has occurred  the minimum concentration of rifampicin required to inhibit growth of the bacterial strain (MIC)  the number of other mutations occurring within the specific region of rpoB gene. Table 1.2 With reference to Table 1.2, (i) complete Table 1.2 to show the amino acid changes that have o ccurred in strains F and G; [1] (ii) list the strains of TB bacteria that show the greatest resistance to rifampicin; …………………………….……………….…..……………….………………….……………… [1]

7 [TURN OVER (iii) suggest reasons to explain why strains C, D and E show different levels of resistance to rifampicin. ……………………..…………………….…………………………………………………………… ……………………..…………………….…………………………………………………………… ……………………..…………………….…………………………………………………………… ……………………..…………………….…………………………………………………………… …………………………….……………….…..……………….………………………………… [2] In a different study involving HIV, it has been theorized that HIV evolved from Simian virus moving from chimpanzees and sooty mangabeys to infect humans. Studies on a particular strain of Simian virus, SV40 has been s hown to induce tumours in laboratory animals by causing cells to divide in an unregulated way. Large T antigen (Tag) is a protein encoded by the SV40 genome. This protein is essential for SV40’s tumour-forming capabilities. Tag has been shown to bind to and inactivate the tumour suppressor p53 protein. (h) Give one role of p53 protein in a normal cell. …………………….………………………………………………………………………………………… .……………….…..……………………………………………………………………………………… [1] (i) Explain how the interaction of Tag with p53 protein would disr upt the normal control of cell division. …………….….…………………………………………………………………………………………….. …………….….…………………………………………………………………………………………….. …………….….…………………………………………………………………………………………….. …………………….………………………………………………………………………………………… .……………….…..……………………………………………………………………………………… [2]

8 Human papillomavirus (HPV) is another virus that inhibits p53. HPV can cause the development of cervical intraepithelial neoplasia (CIN), which leads to cervical cancer. A recent study in Scotland assessed the impact of vaccination against HPV on the development of CIN. Fig. 1.1 shows the effect of HPV -vaccination on the percentage of women found to have the most severe grade of CIN. Fig. 1.1 (j) Explain how the data supports the suggestion that vaccination against HPV is effecti ve in preventing development of CIN in both groups of women. …………….….………………………………