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). …………………………………………………………………………………..………………. …………………………………………………………………………………..………………. …………………………………………………………………………………..………………. …………………………………………………………………………………..………………. …………………………………………………………………………………..………………. …………………………………………………………………………..……