H2 Bio 2024 YIJC Prelim Paper 4 (QP)

1 @YIJC 9744/04/PE/2024 [Turn over YISHUN INNOVA JUNIOR COLLEGE JC2 PRELIMINARY EXAMINATION Higher 2 CANDIDATE NAME CG INDEX NO. H2 BIOLOGY 9744/04 22 Aug 2024 2 hours 30 minutes READ THESE INSTRUCTIONS FIRST Write your name and class in the spaces at the top of this page. Write in dark blue or black pen only. You may use a soft pencil for any diagrams or graphs. Do not use paper clips, highlighters, glue or correction fluid. Answer all questions in the spaces provided on 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 For Examiner’s Use 1 22 2 16 3 17 Total 55 This document consists of 20 printed pages.

2 @YIJC 9744/04/PE/2024 [Turn over 1 Plant tissues contain the enzyme catalase which catalyses the breakdown of hydrogen peroxide into oxygen gas and water. Ascorbic acid acts as an inhibitor of catalase. You will investigate the effect of changing ascorbic acid concentration on catalase activity. You are provided with the materials shown in Table 1.1. Table 1.1 If H or A comes into contact with your skin, wash off immediately under cold water. It is recommended that you wear suitable eye protection. You are also provided with five cylinders of potato tissue, labelled P. (a) You will need to carry out a serial dilution of the 1moldm–3 ascorbic acid, A, to reduce the concentration by a factor of ten between each successive dilution. You will need to prepare four concentrations of ascorbic acid in addition to the 1moldm–3 ascorbic acid solution, A. After the serial dilution is completed, you will need to have at least 9 cm3 of each concentration available to use.

3 @YIJC 9744/04/PE/2024 [Turn over (i) Complete Table. 1.2 to show how you will prepare your serial dilution. Table 1.2 shows the first two beakers you will use to make your serial dilution. You will need to complete three additional beakers. For each beaker, state: • the concentration of the ascorbic acid prepared • the concentration of the ascorbic acid transferred • the volume of ascorbic acid solution transferred • the volume of distilled water, W, added. Table 1.2 Concentration of ascorbic acid / moldm-3 Concentration of the ascorbic acid transferred / moldm-3 volume of ascorbic acid solution transferred / cm3 volume of distilled water, W, added / cm3 1.0 1.0 10.0 0.0 0.1 1.0 1.0 9.0 [3] Carry out step 1 to step 13. 1 Prepare the concentrations of ascorbic acid solution, as decided in (a)(i), in the beakers provided. 2 Label the test‐tubes with the ascorbic acid concentrations prepared in step 1. 3 Label another test‐tube 0. 4 On a white tile carefully cut the cylinders of potato tissue into thin discs that are approximately 1 – 2mm thick. You will need to cut at least 70 discs. 5 Place 10 potato discs into each labelled test‐tube. 6 Add 1cm3 distilled water, W, to the test‐tube labelled 0. 7 Add 1cm3 of each concentration of ascorbic acid to the appropriately labelled test‐tubes.

4 @YIJC 9744/04/PE/2024 [Turn over 8 Set up the apparatus as shown in Fig. 1. 1 using the test ‐tube labelled 0. The syringe barrel should be fully submerged in the beaker of water, B. Fig 1.1 9 Add 5 cm3 of hydrogen peroxide solution H to the test‐tube labelled 0. Place the bung into the top of the test‐tube, making sure that the syringe barrel stays fully submerged. 10 Record in (a)(ii) the initial volume of gas in the syringe barrel, then start the stopwatch. 11 After 2 minutes record in (a)(ii) the final volume of gas in the syringe barrel. If the syringe barrel is full of gas, record as 10. 12 Repeat step 9 to step 11 with each of the test‐tubes labelled in step 2. 13 Calculate the total volume of gas produced at each concentration of ascorbic acid. Record these processed results in (a)(ii). (ii) Record your results in an appropriate table, including raw results and processed results. [6]

5 @YIJC 9744/04/PE/2024 [Turn over (iii) Use your results in (a)(ii) to identify the greatest volume of gas produced in the reaction. greatest volume of gas produced = ............................................................... Use your answer to calculate the rate of gas production. Show your working. rate of gas production = ............................................... cm3min–1 [2] (iv) Describe two improvements to the procedure that would make the measurements more accurate. [2] Carry out step 14 to step 18. 14 Label a test‐tube T. 15 Put 5 cm3 of H into test‐tube T. 16 Use a thermometer to measure the temperature of H in test‐tube T. Record this value, to the nearest 0.5°C, in (b)(i). 17 Add 10 discs of potato tissue to test‐tube T and start timing. 18 After 2 minutes, measure the temperature of the mixture in test‐tube T. Record this value, to the nearest 0.5°C, in (b)(i).

6 @YIJC 9744/04/PE/2024 [Turn over (b) (i) State the temperature of H before adding potato discs (step 16). .............................. °C State the temperature of H 2 minutes after adding potato discs (step 18). .............................. °C Calculate the change in temperature after 2 minutes. .............................. °C [2] (ii) State whether temperature is a significant source of error in this investigation. Explain your answer. [1]

7 @YIJC 9744/04/PE/2024 [Turn over (c) A study was carried out in which volunteers were given different daily doses of ascorbic acid (vitamin C) in addition to their normal diet. The maximum ascorbic acid concentration in the blood plasma of each volunteer was measured. The results are shown in Table 1.3. Table 1.3 (i) Plot a graph of the data in Table 1.3 on the grid shown below. Use a sharp pencil. [4]

8 @YIJC 9744/04/PE/2024 [Turn over (ii) Suggest an explanation for the results for a daily dose of 0mg and the results for daily doses of between 500–1000mg. [2] [Total: 22]

9 @YIJC 9744/04/PE/2024 [Turn over 2 A group of students investigated two habitats: dense woodland and open grassland. • Trees are the dominant plants in woodland. The trees form a canopy under which flowering herbs, small shrubs and grasses grow. • Grasses are the dominant plants in grassland. The grasses and small flowering plants form a continuous ground cover with only a few small shrubs present. Fig. 2.1 shows photographs of the two areas. Fig. 2.1 The students decided to compare the adaptations for reducing water loss in the plants growing in each area. The students suggested the following hypothesis: The density of stomata will be higher in plants found in the woodland habitat than in the grassland habitat. (a) (i) State the independent and dependent variables in this investigation. Independent variable: Dependent variable: [2]

10 @YIJC 9744/04/PE/2024 [Turn over The students collected leaves from a number of different plant species in each area. To study the density of stomata on leaves, impressions of the epidermis can be made using clear varnish. • One surface of each leaf is painted with a thin layer of varnish. • The varnish is left to dry. • Clear sticky tape is applied to the leaf over the varnished area, to make a leaf impression. • The tape and varnish are