2024 EJC Prelim Biology P4 (Q)

© EJC 2024 9744/04/J2H2PRELIM/2024 16 EUNOIA JUNIOR COLLEGE JC2 Preliminary Examinations 2024 General Certificate of Education Advanced Level Higher 2 CANDIDATE NAME CIVICS GROUP 2 3 - REGISTRATION NUMBER BIOLOGY Paper 4 Practical 9744/04 22 August 2024 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 21 printed pages and 3 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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© EJC 2024 9744/04/J2H2PRELIM/2024 3 [Turn over Answer all questions. 1 You will be investigating the effect of salt concentration on the movement of water in potatoes. You are provided with the materials shown in Table 1.1. Table 1.1 labelled contents hazard volume / cm3 P 5 lengths of potato none – W distilled water none 150 S 1 mol dm–3 salt solution none 150 It is recommended that you wear suitable eye protection. (a) You will need to make different concentrations of salt solution using simple dilution of the 1.00 mol dm–3 salt solution, S. You will need to prepare 40 cm3 of each concentration. Table 1.2 shows two of the concentrations you will use. Decide which other concentrations of salt solution you will use. (i) Complete Table 1.2 to show how you will prepare the other concentrations. Table 1.2 final concentration of salt solution / mol dm–3 volume of S / cm3 volume of distilled water, W / cm3 1.00 0.00 40 0 0 40 [2]

© EJC 2024 9744/04/J2H2PRELIM/2024 4 Carry out step 1 to step 11. step 1 Prepare the concentrations of salt solution, as shown in Table 1.2, in the beakers provided. step 2 Cut 10 discs of potato for each of the concentrations prepared in step 1. Each disc should be approximately 3 mm thick. step 3 Place 10 discs in a line as shown in Fig. 1.1. centimetre Fig. 1.1 step 4 Measure the total length of the 10 discs and record this value in 1(a)(ii). step 5 Put the 10 discs into the beaker containing 1 mol dm–3 salt solution. step 6 Repeat step 3 to step 5 with the other discs and the salt solutions you prepared in step 1. step 7 Start timing and leave for 30 minutes. Use this time to continue with other parts of Question 1. step 8 After 30 minutes (step 7), discard the 1 mol dm –3 salt solution from around the discs and tip the discs onto some paper towel. step 9 Place the 10 discs in a line as in Fig. 1.1 and measure their total length. Record this value in 1(a)(ii). step 10 Repeat step 8 and step 9 for the other salt concentrations. step 11 Calculate the change in length for each line of 10 discs. not to scale discs 1 2 3 4 5 6 7 8 9

© EJC 2024 9744/04/J2H2PRELIM/2024 5 [Turn over (ii) Record your results in an appropriate table, including raw results and processed results. [5] (iii) Explain your results for the 0.0 mol dm–3 salt solution (distilled water). ……………………………………………………………………………………………………… ……………………………………………………………………………………………………… ……………………………………………………………………………………………………… …………………………………………………………………………………………………… [2] (iv) Suggest why a line of 10 discs was measured instead of a single disc. ……………………………………………………………………………………………………… …………………………………………………………………………………………………… [1] (v) Identify one significant source of error in this investigation. ……………………………………………………………………………………………………… …………………………………………………………………………………………………… [1]

© EJC 2024 9744/04/J2H2PRELIM/2024 6 (vi) Use your results to estimate a salt concentration where there is no net movement of water into or out of the potato. salt concentration .......................................... mol dm–3 [1] (vii) Describe two improvements to your procedure that would make the estimate in 1(a)(vi) more accurate. a. …………………………………………………………………………………………………… …………………………………………………………………………………………………… b. …………………………………………………………………………………………………… ……………………………………………………………………………………………………. [2]

© EJC 2024 9744/04/J2H2PRELIM/2024 7 [Turn over (b) The salt content of unprocessed food was measured. The values are shown in Table 1.3. Table 1.3 food type salt content of unprocessed food / mg per 100 g food potatoes (P) 10.0 tuna (T) 40.0 bran (B) 25.0 chicken (C) 50.0 salmon (S) 95.0 (i) Plot a bar chart of the data shown in Table 1.3 on the grid in Fig. 1.2. Use a sharp pencil. [4] Fig. 1.2

© EJC 2024 9744/04/J2H2PRELIM/2024 8 The salt content of the same foods that had been processed was also measured. The values are shown in Table 1.4. Table 1.4 food type salt content of processed food / mg per 100 g food potatoes (P) 200.0 tuna (T) 300.0 bran (B) 1000.5 chicken (C) 350.5 salmon (S) 1800.0 (ii) Calculate the percentage increase in salt content when salmon is processed. Show your working and write your answer to two significant figures. increase in salt content ..................................................... % [2] [Total: 20]

© EJC 2024 9744/04/J2H2PRELIM/2024 9 [Turn over 2 Hydrogencarbonate indicator is a water-soluble solution that can act as a source of carbon dioxide for aquatic photosynthetic organisms. The solution changes colour depending on the concentration of carbon dioxide in the solution. These colours are related to different pH values, as shown in Table 2.1. Table 2.1 colour of hydrogencarbonate indicator solution pH concentration of carbon dioxide in the solution yellow 7.6 increasing carbon dioxide concentration yellow-orange 7.8 orange 8.0 orange-red 8.2 red 8.4 atmospheric concentration red-magenta 8.6 decreasing carbon dioxide concentration magenta 8.8 magenta-purple 9.0 purple 9.2 Chlorella vulgaris is a protoctist that is single -celled, aquatic and photosynthetic. It can be immobilised in alginate beads. Alginate beads with immobilised C. vulgaris can be used to measure the rate of photosynthesis. (a) A student noticed that a colour change occurred, from red to magenta, when the alginate beads with immobilised C. vulgaris were left in a container of hydrogencarbonate indicator solution and exposed to light. Explain why this colour change occurred. …………………………………………………………………………………………………………… …………………………………………………………………………………………………………… …………………………………………………………………………………………………………… …………………………………………………………………………………..…………………… [2]

© EJC 2024 9744/04/J2H2PRELIM/2024 10 (b) The student used the alginate beads with immobilised C. vulgaris in hydrogencarbonate indicator solution to investigate the rate of photosynthesis in different light intensities. Fig. 2.1 shows some of the apparatus and reagents the student used. Fig. 2.1 (i) Identify the independent variable in this investigation. ........................................................................................................................................ [1] water small beaker hydrogencarbonate indicator solution large test tube alginate beads containing C