Dunman 2026 6093 P2 prelims QP

This document consists of 24 printed pages DUNMAN SECONDARY SCHOOL CANDIDATE NAME CLASS INDEX NUMBER PRELIMINARY EXAMINATION 2026 SECONDARY 4 EXPRESS BIOLOGY 6093/02 Paper 2 27 August 2026 1 hour 45 minutes Candidates answer on the Question Paper. No Additional Materials are required. READ THESE INSTRUCTIONS FIRST Write your name, class and index number on all the work you hand in. Write in dark blue or black pen. You may use an HB pencil for any diagrams, graphs or rough working. Do not use staples, paper clips, glue or correction fluid. Section A Answer all questions. Write your answers in the spaces provided on the Question Paper. Section B Answer all the questions, the last question is in the form either/or. Write your answers in the spaces provided on the Question Paper. The use of an approved scientific calculator is expected, where appropriate. The number of marks is given in brackets [ ] at the end of each question or part question.

2 6093/02/Prelims/4Exp/2026 Section A Answer all questions. 1 Fig. 1.1 shows a flatworm which lives in ponds, streams and river. The dimension of the flatworm are 12.5 mm long by 3.0 mm wide. Its volume was estimated to be 12.6 mm3. Flatworms do not have a transport system for respiratory gases, oxygen and carbon dioxide. Fig. 1.1 (a) With reference to Fig. 1.1 and the information above, explain how flatworms survive without a transport system for respiratory gases. …………………………………………………………………………………………….…………….. …………………………………………………………………………………………….…………….. …………………………………………………………………………………………….…………….. …………………………………………………………………………………………….…………….. …………………………………………………………………………………………….…………….. …………….………………………………………………………………………….……….…...... [3] (b) Flatworms possess a primitive excretory system composed of specialized units called flame cells. These cells actively pump hydrogen ions and other mineral ions into the excretory tubules. (i) Define the term homeostasis. ……………….………………………………………………..………………………………… ………………………………………………………………..………….……….……….... [1]

3 6093/02/Prelims/4Exp/2026 (ii) Explain why the active transport of ions by the flame cells is important for a flatworm living in a low salt, freshwater environment. ……………….………………………………………………..………………………………… ……………….………………………………………………..………………………………… ……………….………………………………………………..………………………………… ……………….………………………………………………..………………………………… ……………….………………………………………………..………………………………… ………………………………………………………………..………….……….……….... [3] [Total: 7]

4 6093/02/Prelims/4Exp/2026 2 Fig. 2.1 is a diagram of a longitudinal section of a capillary. Fig. 2.1 (a) (i) Name the organelle X and explain how its function enables the phagocyte to carry out its role. X ………………………………………………………….………….……….…….….............. function ……………………………………………….………………………………………… ………………………………………………………………..………….……….……….... [2] (ii) Describe one structural difference between the wall of a capillary and the wall of an artery. Explain how the structural difference relates to the function of that blood vessel. ……………….………………………………………………..………………………………… ……………….………………………………………………..………………………………… ……………….………………………………………………..………………………………… ……………….………………………………………………..………………………………… ……………….………………………………………………..………………………………… ……………….………………………………………………..………………………………… ……………….………………………………………………..………………………………… ………………………………………………………………..………….……….……….... [4] wall of capillary phagocyte X

5 6093/02/Prelims/4Exp/2026 (b) Fig. 2.2 shows the blood pressure changes in the left atrium, left ventricle, and aorta of a human during one complete cardiac cycle. Fig. 2.2 (i) Using Fig. 2.2, identify the specific time interval (in seconds) during which the heart is undergoing ventricular systole. ………………………………………………………………..………….……….……….... [1] key: blood pressure / kPa 16 14 12 10 8 6 4 2 0 - 2 0 0.1 0.2 0.3 0.4 0.6 0.5 0.7 0.8 time/ s atrium ventricle aorta

6 6093/02/Prelims/4Exp/2026 (ii) Describe and explain the flow of blood through the heart during the time interval identified in (b)(i). ……………….………………………………………………..………………………………… ……………….………………………………………………..………………………………… ……………….………………………………………………..………………………………… ………………………………………………………………..………….……….……….... [2] [Total: 9] 3 Fig. 3.1 shows the liver and its associated blood vessels P, Q and R. Fig. 3.1 (a) Identify blood vessels: P ………………………………………………………………………………………….…………….. Q ………………………………………………………………………………………….…………….. R ………………………………………………………………….………………………….….... [3] liver to heart from heart small intestine

7 6093/02/Prelims/4Exp/2026 (b) Describe and explain how a named nutrient transported in Q is stored in the liver. …………………………………………………………………………………………….…………….. …………………………………………………………………………………………….…………….. …………………………………………………………………………………………….…………….. …………………………………………………………………………………………….…………….. …………………………………………………………………………………………….…………….. …………….………………………………………………………………………….……………. [3] (c) The enzyme catalase protects liver cells from oxidative damage by rapidly breaking down hydrogen peroxide into completely harmless substances. Explain the structural basis for the specificity of catalase toward hydrogen peroxide molecules. …………………………………………………………………………………………….…………….. …………………………………………………………………………………………….…………….. …………………………………………………………………………………………….…………….. …………………………………………………………………………………………….…………….. …………………………………………………………………………………………….…………….. …………….………………………………………………………………………….……….….... [3] [Total: 9]

8 6093/02/Prelims/4Exp/2026 4 In long-duration space flight, astronauts can suffer acute kidney injury due to deep-space radiation, causing their kidneys to suddenly stop filtering metabolic waste. The spacecraft is equipped with a compact Micro-Dialysis Unit to clear toxic waste from the astronaut's blood until they return to Earth. Fig. 4.1 shows a simplified cross-section of the dialysis cartridge used on the spacecraft. Fig. 4.1 (a) (i) State the two waste products that will accumulate rapidly in the astronaut's blood if the Micro-Dialysis Unit is not deployed. 1 .………….…………………………………………………………………………………….. 2 .………….………………..………………………………………………………….….... [2] path of blood flow blood flow in blood flow out dialysis tubing (partially permeable membrane) dialysis tubing (partially permeable membrane) dialysis fluid space path of dialysis fluid flow dialysis fluid out dialysis fluid in

9 6093/02/Prelims/4Exp/2026 (ii) Using the structural features shown in Fig, 4.1, explain how the design of the Micro - Dialysis Unit ensures the rapid and continuous removal of metabolic waste from the blood. …………….…………………………………………………………………………………….. …………….…………………………………………………………………………………….. …………….…………………………………………………………………………………….. …………….…………………………………………………………………………………….. …………….…………………………………………………………………………………….. …………….…………………………………………………………………………………….. …………….…………………………………………………………………………………….. …………….………………..………………………………………………………….….... [4] (b) During daily exercise on the space station, an astronaut's body temperature rises during the exercise. Explain how the body detects this change and coordinates a homeostatic response to lower body temperature. …………………………………………………………………………………………….…………….. …………………………………………………………………………………………….…………….. …………………………………………………………………………………………….…………….. …………………………………………………………………………………………….…………….. …………………………………………………………………………………………….…………….. …………………………………………………………………………………………….…………….. …………………………………………………………………………………………….…………….. …………………………………………………………………………………………….…………….. …………………………………………………………………………………………….…………….. …………….………………………………………………………………………….……….…