2025 ASRJC H2Bio PE P3 (Ans)

ASRJC BIOLOGY DEPT 9744/2025/J2PRELIM/P3 [Turn over H2 ANDERSON SERANGOON JUNIOR COLLEGE HIGHER 2 2025 JC2 PRELIMINARY EXAMINATION CANDIDATE NAME CLASS 2 5 / INDEX NUMBER BIOLOGY 9744/03 Paper 3 Long Structured and Free-response Questions Candidates answer on the Question Paper. No Additional Materials are required. 26 August 2025 Tuesday 2 hours READ THESE INSTRUCTIONS FIRST Write your name and class on all the work you hand in. Write in dark blue or black pen. You may use an HB pencil for any diagrams or graph. Do not use 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 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. 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. This document consists of 24 printed pages. For Examiner’s Use 1 2 3 or 4 Total / 75

2 ASRJC BIOLOGY DEPT 9744/2025/J2PRELIM/P3 [Turn over Section A Answer all the questions in this section. 1 The pre valence of type 2 diabetes is steadily increasing. Diabetes occurs either when the pancreas fails to synthesise enough insulin or when insulin resistance develops. Insulin resistance is when the body is unable to respond to insulin. (a) Fig. 1.1 represents, in outline, the basic mechanism involved in the release of insulin from pancreatic β cells in response to increased blood glucose concentrations. not to scale Fig. 1.1 (i) Fig. 1.1 contains the following substances, which are not given to scale: glucose ATP Ca2+ insulin Arrange the substances in order of increasing actual physical size. [1] 1. Ca2+, glucose, ATP, insulin process X

ASRJC BIOLOGY DEPT 9744/2025/J2PRELIM/P3 (ii) Glucose enters the pancreatic β cell via glut2. Outline how glucose is used to increase ATP concentration in the cell in Fig. 1.1. In your answer, highlight specific locations in the cell. [5] (max 3 if at least one correct location is not given) 1. Glucose undergoes glycolysis in the cytosol/ cytoplasm 2. during which (2) ATP is produced via substrate-level phosphorylation (pyruvate from glycolysis is decarboxylated during the link reaction to form acetyl-coA) 3. Acetyl-coA undergoes the Krebs cycle in the mitochondrial matrix 4. during which (2) ATP is produced (per turn ) via substrate-level phosphorylation (award once only) 5. Electrons/ hydrogen from carbon intermediates (derived from glucose) are used to reduce NAD and FAD/ form NADH and FADH2 (during glycolysis, link reaction and Krebs cycle) 6. and are used to produce ATP (a large amount of/ 34 ATP per glucose) during oxidative phosphorylation on the inner mitochondrial membrane 7. AVP, e.g. ATP synthase uses ADP and inorganic phosphate to make ATP, ATP leaves the mitochondrion via carrier protein (iii) Identify process X and explain its significance in Fig. 1.1. [2] 1. exocytosis 2. releases a large amount of insulin quickly/ simultaneously

4 ASRJC BIOLOGY DEPT 9744/2025/J2PRELIM/P3 [Turn over In one study, the effect of blood glucose concentration on insulin secretion was investigated in two groups of people: • people who do not have diabetes • people who have diabetes. In the first experiment, glucose solution was given orally to the people in both groups. Each person was given a drink of 50 g of glucose in 400 cm 3 water. At short time intervals, blood glucose concentrations were recorded for each person, starting from 10 minutes before drinking the glucose solution (–10 minutes) up until three hours after (180 minutes). In the second experiment, which took place several days later, the same people in both groups were given glucose solution that is directly injected into the blood stream throughout the whole period of the experiment (3 hours 10 minutes). No glucose was given orally. The amount of glucose injected was constantly adjusted to give the same blood glucose concentrations that were recorded in the first experiment at the corresponding times. Blood glucose concentrations were recorded for each person at the same short time intervals used in the first experiment, from –10 minutes to 180 minutes. The results for blood glucose concentration are shown in Fig. 1.2. Fig. 1.2 experiment 1 – glucose given orally experiment 2 – glucose directly injected into blood stream

ASRJC BIOLOGY DEPT 9744/2025/J2PRELIM/P3 (b) With reference to Fig. 1.2, compare the effect of glucose given orally on the blood glucose concentration of people who do not have diabetes with the effect on people who have diabetes. [3] 1. Both led to an increase in blood glucose concentration followed by a (gradual) decrease (any 2) 2. peak glucose concentration in non -diabetes people is 1.6 times (accept: 1.5 to 2 times) of baseline vs. significantly higher peak of 2.1 times (accept: 2 – 2.5 times) in diabetes people (or quote absolute difference, i.e. 4 mmol dm-3 vs. higher 9 mmol dm-3) 3. peak glucose concentration in non-diabetes people occurred earlier at 30 min vs. 75 min in diabetes people 4. blood glucose concentration returned to the baseline of 5 mmol dm-3 (accept: 4) by 180 min in non-diabetes people vs. remained higher at 12 mmol dm -3 at 180 min compared to the original 8 mmol dm-3

6 ASRJC BIOLOGY DEPT 9744/2025/J2PRELIM/P3 [Turn over Table 1.1 shows the mean rate of insulin secretion in the two groups of people in the study. It shows that the rate of insulin secretion depends partly on whether glucose is taken orally or directly injected into the blood stream. Table 1.1 mean rate of insulin secretion / nmol dm-3 min-1 oral glucose glucose directly injected into the blood stream people who do not have diabetes 38.9 11.3 people who have diabetes 34.7 23.5 (c) Using the data in Table 1.1, calculate the percentage change in the mean rate of insulin secretion when glucose is taken orally relative to when glucose is directly injected into the blood stream, for people who do not have diabetes. Show your working in the space below. [1] percentage change for people who do not have diabetes = (38.9 – 11.3) / 11.3 x 100% = 244 % (3sf)

ASRJC BIOLOGY DEPT 9744/2025/J2PRELIM/P3 (d) A proportion of the people in the study who have diabetes is unable to syn