2026 NJC H2 Bio Prelim P4 (QP)

©NJC 2026 9477/04/Preliminary Examinations [Turn over NATIONAL JUNIOR COLLEGE, SINGAPORE Senior High 2 Preliminary Examination Higher 2 CANDIDATE NAME BIOLOGY CLASS 2bi2_____ REGISTRATION NUMBER BIOLOGY Paper 4 Practical 9477/04 2 September 2026 2 hour 30 minutes You must answer on the question paper. You will need: The materials and apparatus listed in the confidential instructions INSTRUCTIONS • Answer all questions • Use a black or dark blue pen. You may use an HB pencil for any diagrams or graphs. • Write your name, Biology class and registration number in the boxes at the top of the page. • Write your answer to each question in the space provided. • Do not use an erasable pen. Do not use correction fluid or tape. • You may use an approved calculator. • Write the details of the shift and laboratory in the boxes provided. INFORMATION • The total mark for this paper is 50. • The number of marks for each question or part question is shown in brackets [ ]. Shift 1 2 3 Laboratory BI23 BI24 CM43 CM44 For Examiner’s Use 1 / 31 2 / 19 Total / 50 This document consists of 16 printed and 4 blank pages.

©NJC 2026 9477/04/Preliminary Examinations [Turn over 2 1 Beetroot contains red pigments in its cells. When beetroot is put in ethanol, the red pigment is released from the beetroot tissue, and the solution changes to a red colour. In this question, you will investigate the effect of different concentrations of ethanol on the release of red pigments from beetroot tissue. (a) Predict how increasing the concentration of ethanol will affect the release of red pigments from beetroot tissue. Explain your prediction. prediction explanation [2] You are required to: • prepare different concentrations of ethanol • put beetroot tissue into the different concentrations of ethanol for 5 minutes • record the intensity of colour for different concentrations of ethanol • use your results to estimate the concentration of a solution of ethanol of unknown concentration You are provided with: • 100.0 cm3 of 100% ethanol, labelled E • 10.0 cm3 of an unknown ethanol concentration, labelled U • 300.0 cm3 of distilled water, in a container labelled W • 2 beetroot cylinders, in a Petri dish labelled B Ethanol is flammable and beetroot tissue can stain clothing. You are advised to wear suitable eye protection. If any solution comes into contact with your skin, was h off immediately with tap water.

©NJC 2026 9477/04/Preliminary Examinations [Turn over 3 (b) (i) You will carry out proportional dilutions of the 100% ethanol to obtain a range of concentrations in which the concentration of the ethanol is reduced by 25% between each successive dilution. You will prepare 20.0 cm3 of each concentration, using E and W. Complete Table 1.1 to show how you will prepare the different concentrations of ethanol solution. Table 1.1 percentage concentration of ethanol volume of E / cm3 volume of W / cm3 0 100 [2]

©NJC 2026 9477/04/Preliminary Examinations [Turn over 4 Read steps 1–10 before starting the investigation. Proceed as follows. 1 Label five boiling tubes with the concentrations listed in b(i). 2 Prepare the concentrations of ethanol in plastic containers, using your method in (b)(i). 3 Put 10.0 cm3 of each concentration of ethanol into the appropriately labelled boiling tubes. 4 Place one of the beetroot cylinders from the Petri dish labelled B on the white tile and blot dry with a paper towel. Cut 25 disc-shaped pieces of beetroot, each 2 mm in length, from the beetroot cylinder. 5 Put the beetroot discs into a small beaker. Put enough W to cover the discs in the beaker. Swirl and pour W into the beaker labelled waste. 6 Repeat step 5 until W remains colourless. 7 Put the discs on a white tile and blot dry with a paper towel. 8 Put five discs into each of the boiling tube. Leave for 5 minutes. 9 After 5 minutes, pour the ethanol from each boiling tube into a clean test-tube, leaving the beetroot discs in the boiling tube. Label the test-tube with the appropriate ethanol concentration. 10 Record the colour intensity of each concentration of ethanol using the symbols from Fig. 1.1 in an appropriate table in (b)(ii). Fig. 1.1

©NJC 2026 9477/04/Preliminary Examinations [Turn over 5 (ii) Record your results in an appropriate table. [4] 11 Repeat steps 3–9 using the unknown concentration, U. Record your result in (b)(iii). (iii) Record the result for U. [1] (iv) Estimate the concentration of ethanol in U, using your results recorded in (b)(ii) and (b)(iii). [1] (v) Describe two significant sources of error in the procedure that reduce confidence in your results recorded (b)(ii) and (b)(iii). [2]

©NJC 2026 9477/04/Preliminary Examinations [Turn over 6 (vi) If all significant sources of error were eliminated from this investigation, describe one improvement to this procedure that would enable the estimate of the concentration of U in (b)(iv) to be more accurate. [1] (c) A student hypothesised that the surface area of the beetroot has an effect on the results. Describe how the student will obtain a range of values for the independent variable. [2]

©NJC 2026 9477/04/Preliminary Examinations [Turn over 7 Question 1 continues on page 8

©NJC 2026 9477/04/Preliminary Examinations [Turn over 8 (d) A scientist carried out an investigation into the effect of temperature on the number of beetroot pigments diffusing through 1 cm 2 of a beetroot plasma membrane in 10 minutes. The results are shown in Table 1.2. Table 1.2 Temperature / °C number of beetroot pigments 4 8 16 20 40 48 63 84 92 116 (i) On the grid provided, plot a graph of the data shown in Table 1.2. Draw a line of best fit. [4]

©NJC 2026 9477/04/Preliminary Examinations [Turn over 9 (ii) Use your graph to calculate the percentage increase in the number of molecules diffusing through 1 cm2 of the membrane in 10 minutes when the temperature increases from 50 °C to 60 ºC. Show on your graph where you have obtained your data. Show your working. percentage increase = % [2]

©NJC 2026 9477/04/Preliminary Examinations [Turn over 10 (e) Plan an investigation to determine the concentration of sucrose solution that has the same water potential as the cells of the beetroot. In your plan you must use: • beetroot cylinders • a stock solution of 2.0 mol dm–3 sucrose You may select from the following apparatus and plan to use appropriate additional apparatus: • normal laboratory glassware, e.g. test-tubes, boiling tubes, beakers, measuring cylinders, graduated pipettes, glass rods, etc. • syringes • petri dishes • timer, e.g. stopwatch • weighing balance. Your plan should: • have a clear and helpful structure such that the method you use is able to be repeated by anyone reading it • be illustrated by relevant diagrams, if necessary • identify the dependent and the independent variable • identify the variables you will need to control • use the correct technical and scientific terms • indicate how the results will be recorded and analysed. You should not wash the beetroot in distilled water as this will affect its water potential. You can assume that standard laboratory safety precautions and controls apply.