SAJC 2023 H2 BIO P3 ANS

1 SAJC / H2 Biology 9744/3 JC2 Prelim 2023 Civics Group A Level Index Number Name (use BLOCK LETTERS) ST. ANDREW’S JUNIOR COLLEGE 2023 JC2 PRELIMINARY EXAMINATIONS H2 BIOLOGY 9744/03 Paper 3 Mark scheme Friday 15th September 2023 2 hours READ THESE INSTRUCTIONS FIRST Write your name, civics group and index number on all the work you hand in. Write in dark blue or black pen on both sides of the paper. You may use a soft pencil for any diagram, graph or rough working. Do not use staples, paper clips, highlighters, glue or correction fluid. Answer all questions. Write your answers in the spaces provided on the question paper. All working for numerical answers must be shown. Conceptual error (C) Data Quoting (D) Expression (E) Misreading the question (Q) For Examiners’ Use 1 /40 2 /10 3 or 4 /25 Total /75 This document consists of XX printed pages. [Turn over] H2

2 SAJC / H2 Biology 9744/3 JC2 Prelim 2023 Answer all questions. QUESTION 1 On October 14, 2021, the World Health Organization (WHO) released the Global Tuberculosis Report 2021, which showed that 9.87 million new cases of tuberculosis and 1.5 million people died of tuberculosis in 2020. Among them, the estimated number of new cases of tuberculosis in China in 2020 was 842,000 (833,000 in 2019), and the estimated incidence of tuberculosis was 59/100,000 (58/100,000 in 2019). Among the 30 countries with a high burden of tuberculosis, China ranks second in the number of estimated cases of tuberculosis and has over 30,000 deaths due to tuberculosis. (a)(i) In Fig. 1.1 below, label X and Y appropriately, to reflect the pathogenes is of tuberculosis. Fig. 1.1 [2] Ans: X: Mycobacterium tuberculosis [Reject: bacteria] [Accept: italics] Y: granuloma [Accept: Tubercle]

3 SAJC / H2 Biology 9744/3 JC2 Prelim 2023 (ii) With reference to a cellular organelle in the macrophages, describe how macrophages usually attempt to process engulfed bacteria. ……..………………………………………………………………..…………………..……....[2] 1. Lysosomes contain hydrolytic enzymes in macrophages, (e.g. proteases), which hydrolyzes bacteria; 2. after lysosomes fused with phagosomes/endocytic vesicle containing bacteria; Fig. 1.2 shows the cell wall of the bacteria causing tuberculosis and its unique make up of fatty acids which are slightly different from those used in the synthesis of triglycerides in eukaryotes. Fig. 1.2 (iii) With reference to Fig. 1.2, explain how the bacteria causing tuberculosis can evade the mechanisms of the macrophage host cells. ……..…………………………………………………………………...…………………….....[1] 1. Their mycolic acid wax coat on their cell walls also protects them against hydrolytic enzymes in lysosomes; (iv) Complete and annotate on the diagram below to show the production of a triglyceride from its constituents in eukaryotes. …………………………………………………………………..……………………..…