EJC 2023 JC2 Prelim 9744 H2 Biology P4 (Q)

© EJC 2023 9744/04/J2H2PRELIM/2023 EUNOIA JUNIOR COLLEGE JC2 Preliminary Examinations 2023 General Certificate of Education Advanced Level Higher 2 CANDIDATE NAME 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 18 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

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3 © EJC 2023 9744/04/J2H2PRELIM/2023 [Turn over 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

4 © EJC 2023 9744/04/J2H2PRELIM/2023 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 the boiling tube labelled Y. Mix well. Between step 3 and step 4, you will be leaving the apparatus for 15 minutes. Use this time to continue with other parts of Question 1. step 3 Put boiling tube Y into the water-bath for 15 minutes. step 4 After 15 minutes, remove boiling tube Y from the water-bath. step 5 Stir the mixture in boiling tube Y and pour it into a beaker. step 6 Label the spotting tile with the sample times in minutes, as shown in Fig. 1.2. step 7 Put 3 drops of B onto the spotting tile at each sample time, as shown in Fig. 1.2. Fig. 1.2 3 drops of bromothymol blue solution, B sample times in minutes

5 © EJC 2023 9744/04/J2H2PRELIM/2023 [Turn over Fig. 1.3 shows the apparatus you will set up for this investigation. Fig. 1.3 step 8 Tie a knot in the dialysis tubing as close as possible to one end, so that the end is sealed. step 9 To open the other end, rub the tubing gently between your fingers and thumb. step 10 Stir the mixture in the beaker from step 5 and put 6.0 cm 3 of this mixture into a syringe. step 11 Wipe the outside of the syringe and put the mixture from the syringe into the dialysis tubing. step 12 Rinse the outside of the dialysis tubing by dipping it into the water in the container labelled V. Look carefully at Fig. 1.3 to help you with step 13 to step 15. step 13 Tie a knot just above the level of the mixture in the dialysis tubing, as shown in Fig. 1.3. step 14 Put the dialysis tubing into a clean boiling tube so that it is resting on the bottom of the boiling tube, as shown in Fig. 1.3. step 15 Draw a line on the boiling tube so that it is half-way between the two knots, as shown in Fig. 1.3. This is where you will take your samples from. boiling tube

6 © EJC 2023 9744/04/J2H2PRELIM/2023 step 16 In this step, you will use a syringe to measure the volume of distilled water, W, needed to cover the section of dialysis tubing containing the mixture. Use a syringe to put W into the boiling tube to cover the section of dialysis tubing containing the mixture. (a) (i) State the volume of W that you added to the boiling tube in step 16. volume of W = ………………………………. cm3 [1] step 17 Take a sample of W from the boiling tube at the point you marked in step 15, using a pipette. step 18 Put 3 drops of W onto B at time 0 on the white tile. Put the remaining W in the pipette back into the boiling tube. step 19 Start timing and put the boiling tube containing the dialysis tubing into the beaker labelled water-bath. step 20 Mix the sample of W and B on the white tile and immediately record the colour in (a)(ii), using the colours stated in Fig. 1.1. step 21 Repeat step 17, step 18 and step 20 for each of the sampling times until the end-point (yellow) is reached for two consecutive samples. If the end-point is not reached at 10 minutes, stop timing. (ii) Record your results in an appropriate table. [3]

7 © EJC 2023 9744/04/J2H2PRELIM/2023 [Turn over (iii) This investigation used colour to indicate the concentration of carbon dioxide in the sample. Suggest three improvements to this investigation that would increase the accuracy of the results. 1 …..……………………………………………………………………………………………….. ……..……………………………………………………………………………………………….. 2 …..……………………………………………………………………………………………….. ……..……………………………………………………………………………………………….. 3 …..……………………………………………………………………………………………….. ……..……………………………………………………………………………………………….. [3] (iv) A student wishes to repeat the investigation using the same procedure but with different concentrations of glucose. Using a table, show how the different concentrations of glucose can be made. You need to ensure that a sufficient volume is made for each glucose concentration. [4]

8 © EJC 2023 9744/04/J2H2PRELIM/2023 (v) A student repeated the investigation using the same procedure but with starch as the substrate instead of glucose. Suggest why it took much longer to reach the end-point when starch was used as the substrate. ……..……………………………………………………………………………………………….. ……..……………………………………………………………………………………………….. ……..……………………………………………………………………………………………….. ……..……………………………………………………………………………………………….. ……..……………………………………………………………………………………………….. ……..……………………………………………………………………………………………….. ……..……………………………………………………………………………………………….. ……..……………………………………………………………………………………………….. [4] [Total: 15]

9 © EJC 2023 9744/04/J2H2PRELIM/2023 [Turn over 2 (a) Many p