NYJC 2023 H2 Biology 9744 P3 MS

9744 / H2 Biology / 03 NANYANG JUNIOR COLLEGE JC 2 PRELIMINARY EXAMINATIONS Higher 2 CANDIDATE NAME CLASS BIOLOGY 9744/03 Paper 3 Long Structured and Free-response Questions 20 Sept 2023 2 hours READ THESE INSTRUCTIONS FIRST Write your name and CT on all the work you hand in. Write in dark blue or black pen. You may use an HB pencil for any diagrams or graphs. 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 on the separate Answer 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 no use appropriate units. At the end of the examination, fasten all your work securely together. The number of marks is given in brackets [ ] at the end of each question or part question. For Examiner’s Use Section A 1 29 2 12 3 9 Section B (a) 13 (b) 12 Total 75 This document consists of 14 printed pages. [Turn over

9744 / H2 Biology / 03 2 Section A Answer all the questions in this section. 1 (a) Tuberculosis (TB) is a major cause of ill health worldwide. Prokaryotic Mycobacterium tuberculosis is the causative agent of TB. Fig. 1.1 shows the longitudinal section of M. tuberculosis , viewed under the transmission electron microscope, with a scale bar representing 500nm. Source: Muhsin Özel, Gudrun Holland/RKI Fig. 1.1 (i) List two features visible in Fig. 1.1 that identify these cells as prokaryotes. Presence of (peptidoglycan) cell wall; Unicellular; [2] (ii) Outline the process by which M. tuberculosis reproduce. Binary fission; semi-conservative replication of parental DNA begins at the origin of replication each origin moves rapidly toward the opposite end of the cell and adhere to the cell surface membrane. cell elongates. Elongation of the cell also separates the two identical copies of the chromosomes. cell surface membrane invaginates, and deposits new c ell wall materials. Two daughter cells are formed which are genetically identical to the parent cell.

9744 / H2 Biology / 03 3 [4] (iii) Identify and explain one problem of trying to classify prokaryotes such as M. tuberculosis. P1 hard to classify prok on, phenotype / morphology / appearance ; R1 as, small / simple / single-celled / share similar cell structure / have limited range of cell shapes OR P2 idea that (biological) species concept does not apply to bacteria ; R2 as they reproduce asexually ; [2] (b) The World Health Organization (WHO) introduced a strategy in 2015 to end the global TB epidemic. An important part of the strategy is to: • identify people at risk of becoming infected with TB • use methods to prevent transmission of TB.