EJC 2023 JC2 Prelim 9744 H2 Biology P4 (ANS)

© EJC 2023 9744/04/J2H2PRELIM/2023 EUNOIA JUNIOR COLLEGE JC2 Preliminary Examinations 2023 General Certificate of Education Advanced Level Higher 2 CANDIDATE NAME ANSWER KEY CIVICS GROUP 2 2 - REGISTRATION NUMBER BIOLOGY Paper 4 Practical 9744/04 24 August 2023 2 hours 30 minutes Candidates answer on the Question Paper. READ THESE INSTRUCTIONS FIRST Write your name, civics group and registration number on all the work you hand in. Give details of the practical shift and laboratory, where appropriate, in the boxes provided. Write in dark blue or black pen. You may use an HB pencil for any diagrams or graphs. Do not use stapler, paper clips, highlighters, glue or correction fluid/tape. This document consists of 22 printed pages and 2 blank pages. For Examiner’s Use 1 2 3 Total 55 Answer all questions in the spaces provided in 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. Shift Laboratory

2 © EJC 2023 9744/04/J2H2PRELIM/2023 Answer all questions. 1 Yeast cells contain enzymes that catalyse metabolic reactions. Some of these reactions release carbon dioxide. You will investigate the release of carbon dioxide from a mixture of yeast and carbohydrate. The mixture is put into dialysis (Visking) tubing. The dialysis tubing acts as a partially permeable membrane, allowing the carbon dioxide to diffuse out of the dialysis tubing. You are provided with the materials shown in Table 1.1. Table 1.1 labelled contents hazard volume / cm 3 Y 1g dried yeast in boiling tube none - G 10.0% warm glucose solution none 20 W distilled water none 50 B bromothymol blue indicator solution harmful 10 V 20 cm length dialysis tubing in a beaker of distilled water none - If any solution comes into contact with your skin, wash off immediately under cold water. It is recommended that you wear suitable eye protection. To test for the release of carbon dioxide, a sample of the water surrounding the dialysis tubing is added to drops of an indicator, B. Fig. 1.1 shows the effect of increasing concentration of carbon dioxide on the colour of B. Yellow is the end-point. Fig. 1.1 BLUE blue-green GREEN green-yellow YELLOW no carbon dioxide highest concentration of carbon dioxide

3 © EJC 2023 9744/04/J2H2PRELIM/2023 [Turn over Carry out step 1 to step 21. step 1 Using the beakers labelled hot water and cold water, adjust the water in the beaker labelled water-bath to 45 °C. You will not need to maintain this temperature. step 2 Put 15 cm3 of G into th