Jurongville Pure Biology Prelim 2024 Paper 2

JVSS Prelim 2024 4E Biology 6093/02 [Turn over JURONGVILLE SECONDARY SCHOOL PRELIMINARY EXAMINATION 2024 Secondary 4 Express STUDENT NAME CLASS INDEX NUMBER BIOLOGY 6093/02 Paper 2 12 August 2024 1 hour 45 minutes Candidates answer on the Question Paper. READ THESE INSTRUCTIONS FIRST Write your name, class and index number in the spaces on all the work you hand in. Write in dark blue or black pen. You may use pencil for drawing diagrams or graphs. Do not use staples, paper clips, highlighters, glue or correction fluid. Section A Answer ALL questions. Write your answers in the spaces provided. Section B Answer one question. Write your answers in the spaces provided. 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 DO NOT OPEN THE BOOKLET UNTIL YOU ARE TOLD TO DO SO For Examiner’s Use Section A Section B Total This document consists of 19 printed pages. Setter: Ms Jo-Ann Lee Hui 70 10 80

2 JVSS Prelim 2024 4E Biology 6093/02 [Turn over Section A: Structured Questions [50 marks] Answer all questions. Write your answers in the spaces provided. 1 A substance called phenol that is found in the flesh of apples turns brown when it is exposed to air for a period of time. This browning involves an enzyme called polyphenol oxidase which catalyses the conversion of phenol found in apples to a brown compound called melanin. A student carried out an investigation of the action of polyphenol oxidase on phenol. Four test -tubes were set up with different contents as follows: test tube test tube contents 1 2 3 4 5 phenol + polyphenol oxidase solution phenol + boiled polyphenol oxidase solution phenol + polyphenol oxidase solution + dilute hydrochloric acid phenol + polyphenol oxidase solution + aqueous sodium hydroxide phenol + distilled water Each test-tube was shaken thoroughly and then placed in a water bath that was maintained at 40 °C. After some time, the observations for each test tubes were recorded in T able 1.1. Table 1.1 test tube 1 2 3 4 5 colour at the start of the experiment colourless colourless colourless colourless colourless colour at the end of the experiment brown colourless colourless (a) (i) Fill in the blanks in Table 1.1 by stating the colour at the end of the experiment for test - tubes 1 and 2. [2] (ii) Explain your answer for (a)(i). …………………………………………………………………………………..………………. …………………………………………………………………………………..………………. …………………………………………………………………………………..………………. …………………………………………………………………………………..………………. …………………………………………………………………………………..………………. …………………………………………………………………………..…………………… [ 3]

3 JVSS Prelim 2024 4E Biology 6093/02 [Turn over (b) State the reason for the result in test-tube 4. ………………………………………………………………………………………..………………… …..………………………………………………………………………………………..………… [1] (c) Explain the purpose of test-tube 5. ………………………………………………………………………………………..………………… …..………………………………………………………………………………………..………… [ 1] (d) Suggest two factors that must be kept constant during the investigation. ………………………………………………………………………………………..………………… ………………………………………………………………………………………..………………… …..………………………………………………………………………………………..………… [ 2] [Total: 9]

4 JVSS Prelim 2024 4E Biology 6093/02 [Turn over 2 In an investigation, the volume of samples of 20 dried raisins was measured. Each sample was then placed in water or sugar solutions of different concentrations. After 12 hours, the raisins were blotted dry and the volume of each sample of raisins was measured again. Fig. 2.1 shows the results. Fig. 2.1 (a) Explain why samples of 20 raisins were used rather than a sample of one raisin. ………………………………………………………………………………………..………………… …..………………………………………………………………………………………..………… [1] (b) Calculate the percentage increase in the volume of the sample of raisins in 5% sugar solution. ……………………………..……% [2] (c) Explain the results in the 10% sugar solution. ………………………………………………………………………………………..………………… ………………………………………………………………………………………..………………… ………………………………………………………………………………………..………………… …..………………………………………………………………………………………..………… [2] [Total: 5] volume / cm3 at start after 12 hours percentage sugar concentration

5 JVSS Prelim 2024 4E Biology 6093/02 [Turn over 3 Fig. 3.1 shows a human heart in which the coronary arteries are partially blocked. A coronary by-pass operation is a remedy for this. It involves grafting sections of vein from the patient’s leg to the heart. Fig. 3.1 (a) Name A and B on the diagram. [2] (b) Explain how blockages in coronary arteries affect the heart’s ability to work. ………………………………………………………………………………………..………………… ………………………………………………………………………………………..………………… …..………………………………………………………………………………………..………… [2] (c) Suggest why a blockage at X will have more serious consequences than a blockage at Y. ………………………………………………………………………………………..………………… …..………………………………………………………………………………………..………… [1] (d) Suggest why a coronary by-pass is preferable to a heart transplant operation. ………………………………………………………………………………………..………………… …..………………………………………………………………………………………..………… [1] (e) State two precautions that can be taken to reduce the risk of coronary heart disease. ………………………………………………………………………………………..………………… ………………………………………………………………………………………..………………… …..………………………………………………………………………………………..………… [ 2] [Total: 7] 4 A seal is a mammal that spends most of its time in the sea. It breathes and respires in a similar wa y A: …………………………. B: …………………………. X blockage at Y coronary artery

6 JVSS Prelim 2024 4E Biology 6093/02 [Turn over to humans, but when it dives to hunt and catch fish, can stay under water for an extended length of time each dive. Fig. 4.1 shows the percentage concentrations of oxygen, carbon dioxide and lactic acid in a seal’s blood over a 40 minute period during which it dives to hunt for fish at some point. Fig. 4.1 (a) Write a word equation of the process taking place in the seal’s muscles before it dives. …..………………………………………………………………………………………..………… [1] (b) State the time the seal starts its dive. ………………..… min [1] (c) Describe and explain the relationship between the concentration of oxygen and lactic acid from time 20 min to 40 min. ………………………………………………………………………………………..………………… ………………………………………………………………………………………..………………… ………………………………………………………………………………………..………………… …..………………………………………………………………………………………..………… [ 2] percentage concentration of blood gases / % concentration of lactic acid / mmol per dm3 time / min lactic acid oxygen carbon dioxide

7 JVSS Prelim 2024 4E Biology 6093/02 [Turn over (d) Suggest and explain what would happen to the concentration of lactic acid in the seal’s blood when it returns to the surface of the sea after its dive. ………………………………………………………………………………………..………………… ………………………………………………………………………………………..………………… ………………………………………………………………………………………..………………… ………………………………………………………………………………………..………………… …..………………………………………………………………………………………..………… [ 3] [Total: 7]

8 JVSS Prelim 2024 4E Biology 6093/02 [Turn over 5 An investigation was carried out into the effect of eating two different sources of carbohydrate on the concentration of glucose and the concentration