2025 TMJC H2Bio PE P2 (QP)

CANDIDATE NAME CIVICS GROUP H2 BIOLOGY 9744/02 Paper 2 Structured Questions 17 September 2025 2 hours Candidates answer on the Question Paper. No additional materials are required. READ THESE INSTRUCTIONS FIRST Write your name and Civics Group in the spaces at the top of the 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. Answer all questions in the 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 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 31 printed pages and 3 blank pages. For examiner’s Use 1 / 13 2 / 7 3 / 9 4 / 7 5 / 7 6 / 13 7 / 7 8 / 10 9 / 9 10 / 8 11 / 10 Total / 100 TAMPINES MERIDIAN JUNIOR COLLEGE JC2 PRELIMINARY EXAMINATION

2 Tampines Meridian Junior College 2025 JC2 Preliminary Examination H2 Biology Answer all questions. 1. Fig. 1.1 shows a diagram of a glycosphingolipid, a type of lipid found in the cell surface membranes of most eukaryotic organisms. Fig. 1.1 (a) Compare the structures of the glycosphingolipid and phospholipids. [2] ………………………………………………………………………………………………………... ………………………………………………………………………………………………………... ………………………………………………………………………………………………………... ………………………………………………………………………………………………………... ………………………………………………………………………………………………………... (b) Suggest a role of the glycosphingolipid in the cell surface membrane. [1] ………………………………………………………………………………………………………... ………………………………………………………………………………………………………... (c) Glucocerebrosidase is a glycosidase enzyme that breaks down glycosphingolipids by removing the saccharide portion of the molecule. Another example of a glycosidase enzyme is maltase that breaks down maltose into glucose molecules. Draw an arrow in Fig. 1.1 to show which bond glucocerebrosidase hydrolyses in the glycosphingolipid. [1]

3 Tampines Meridian Junior College 2025 JC2 Preliminary Examination H2 Biology (d) Fig. 1.2 shows the results of an experiment conducted to investigate the activity of glucocerebrosidase at various pH levels. Fig. 1.2 Explain why there is no enzyme activity below pH 3. [3] ………………………………………………………………………………………………………... ………………………………………………………………………………………………………... ………………………………………………………………………………………………………... ………………………………………………………………………………………………………... ………………………………………………………………………………………………………... ………………………………………………………………………………………………………... ………………………………………………………………………………………………………...

4 Tampines Meridian Junior College 2025 JC2 Preliminary Examination H2 Biology (e) Another experiment was conducted to investigate the effect of substrate concentration on the activity of glucocerebrosidase, with and without a chemical called isofagomine. The results are shown in Fig. 1.3. Fig. 1.3 (i) Describe and explain the results of the experiment at substrate concentrations above 10 µmol dm-3 for the reaction without isofagomine. [2] …………………………………………………………………………………………………... …………………………………………………………………………………………………... …………………………………………………………………………………………………... …………………………………………………………………………………………………... …………………………………………………………………………………………………...

5 Tampines Meridian Junior College 2025 JC2 Preliminary Examination H2 Biology (ii) With reference to Fig. 1.3, explain the effect of isofagomine on the rate of enzymatic activity. [4] …………………………………………………………………………………………………... …………………………………………………………………………………………………... …………………………………………………………………………………………………... …………………………………………………………………………………………………... …………………………………………………………………………………………………... …………………………………………………………………………………………………... …………………………………………………………………………………………………... …………………………………………………………………………………………………... …………………………………………………………………………………………………... [Total: 13]

6 Tampines Meridian Junior College 2025 JC2 Preliminary Examination H2 Biology 2. Fig. 2.1 shows the movement of three different substances across a cell surface membrane. Fig. 2.1 (a) Explain why transmembrane proteins are needed to transport glucose and potassium ions across the cell surface membrane. [3] ………………………………………………………………………………………………………... ………………………………………………………………………………………………………... ………………………………………………………………………………………………………... ………………………………………………………………………………………………………... ………………………………………………………………………………………………………... ………………………………………………………………………………………………………... ………………………………………………………………………………………………………... (b) Describe one difference between the mechanism of transport of glucose and potassium ions across the cell surface membrane. [1] ………………………………………………………………………………………………………... ………………………………………………………………………………………………………... ………………………………………………………………………………………………………...

7 Tampines Meridian Junior College 2025 JC2 Preliminary Examination H2 Biology (c) Fig. 2.1 shows insulin being released out of the cell via exocytosis. Describe how insulin synthesised by ribosomes is transported to the cell surface membrane. [3] ………………………………………………………………………………………………………... ………………………………………………………………………………………………………... ………………………………………………………………………………………………………... ………………………………………………………………………………………………………... ………………………………………………………………………………………………………... ………………………………………………………………………………………………………... ………………………………………………………………………………………………………... [Total: 7]

8 Tampines Meridian Junior College 2025 JC2 Preliminary Examination H2 Biology 3. When there is insufficient oxygen in the cell, ATP is synthesised via anaerobic respiration. Fig. 3.1 shows one of the reactions occurring during anaerobic respiration in humans. This reaction is catalysed by lactate dehydrogenase. Fig. 3.1 (a) Identify (i) molecule A, [1] …………………………………………………………………………………………………… (ii) molecules B and C. [1] B …………………………… C …………………………… (b) State the location in the cell where this reaction occurs. [1] ………………………………………………………………………………………………………... (c) Explain the importance of this reaction in the production of ATP. [2] ………………………………………………………………………………………………………... ………………………………………………………………………………………………………... ………………………………………………………………………………………………………... ………………………………………………………………………………………………………... ………………………………………………………………………………………………………...

9 Tampines Meridian Junior College 2025 JC2 Preliminary Examination H2 Biology (d) Fig. 3.2 shows the structure of lactate dehydrogenase 3 (LDH -3), which is found in the lungs. Fig. 3.2 With reference to Fig. 3.1 and Fig. 3.2, describe the structural differences between LDH-3 and haemoglobin. [2] ………………………………………………………………………………………………………... ………………………………………………………………………………………………………... ………………………………………………………………………………………………………... ………………………………………………………………………………………………………... ………………………………………………………………………………………………………... (e) Lactate dehydrogenase is an allosteric enzyme. Explain how allosteric activators increase the rate of enzymatic activity in lactate dehydrogenase. [2] ………………………………………………………………………………………………………... ………………………………………………………………………………………………………... ………………………………………………………………………………………………………... ………………………………………………………………………………………………………...