TJC 2023 H2 Prelim P4 QP

1 [TURN OVER TEMASEK JUNIOR COLLEGE 2023 JC2 PRELIMINARY EXAMINATION Higher 2 CANDIDATE NAME CENTRE NUMBER S INDEX NUMBER BIOLOGY 9744/04 Paper 4 Practical 30 August 2023 2 hour 30 minutes Candidates answer on the Question Paper. Additional Materials: As listed in the Confidential Instructions. READ THESE INSTRUCTIONS FIRST Write your name, CG, Centre number, index 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 staples, paper clips, glue or correction fluid. This document consists of 16 printed pages. Shift Laboratory For Examiner’s Use 1 / 17 2 / 17 3 / 21 Total / 55 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 work or if you do no use appropriate units. At the end of the examination, fasten all your work securely together. The number of marks is given in brackets [ ] at the end of each question or part question.

2 Answer all questions. 1 (a) You will investigate the effect of different temperatures on the permeability of the cell surface membrane of beetroot cells. Beetroot is a vegetable that contains a red pigment in its cells. When beetroot tissue is put into water, the red pigment can move out of the cells through the cell surface membrane, changing the water to a red colour. You are provided with: labelled contents hazard volume / cm 3 B 4 pieces of beetroot none - W distilled water none 100.0 The red pigment in beetroot cells can stain clothing and skin. Use blunt forceps to handle beetroot tissue and, if any pigment comes into contact with your skin, wash it off immediately under cold water. It is recommended that you wear suitable eye protection. You will need to:  put beetroot tissue in water at different temperatures  leave the beetroot tissue in the water for a period of time  record the intensity of colour in the water at each temperature. (i) The temperature range that you will use must include a minimum temperature of 25˚C and a maximum temperature of 65˚C. State other temperatures that you will use in your investigation. …………………………………………………………………………………………………… [1]

3 [TURN OVER Read step 1 to step 13 before proceeding. Proceed as follows. 1 Cut the beetroot pieces into 2 mm thick discs. You will need at least 25 discs. 2 Put all the discs that you have cut into the beaker labelled D and cover them with approximately 30 cm3 distilled water, W. 3 Stir with a glass rod. 4 Pour off the water into the beaker labelled For waste, leaving the discs in the beaker labelled D. 5 Put all the discs on a paper towel and blot them to remove excess water. 6 Set up and maintain a water-bath at 25˚C, using the beaker labelled water-bath. The water- bath will be needed in step 9. 7 Put five discs into one test-tube. 8 Put 10 cm3 of distilled water, W, into the test-tube with the five discs. 9 Put this test-tube into the water-bath for four minutes. You will need to maintain the water-bath at the correct temperature throughout these four minutes. 10 After four minutes, remove the test-tube with the discs from the water-bath. 11 Pour the water from this test-tube into a second test-tube, leaving the discs in the first test-tube. 12 Repeat step 1 to step 11 until all of the temperatures stated in (a)(i) have been tested, finishing with the maximum temperature of 65˚C. 13 Observe the colour intensity of the water in each of the test-tubes in the test-tube rack.

4 14 Using only the symbols shown in Table 1.1 to represent intensity of colour, decide the intensity of colour in each of the test-tubes in the test-tube rack. Record your results in (a)(ii). Table 1.1 intensity of colour symbol dark red ++++++ decreasing intensity of red colour +++++ ++++ +++ ++ no colour + (ii) Record your results in an appropriate table, using only the symbols shown in Table 1.1. [4]

5 [TURN OVER (iii) Use your knowledge of cell surface membranes to explain the results that you recorded in (a)(ii). ………………………………………………………………………………………………………. ………………………………………………………………………………………………………. ………………………………………………………………………………………………………. ………………………………………………………………………………………………………. ………………………………………………………………………………………………………. ………………………………………………………………………………………………………. …………………………………………………………………………………………………… [3] (iv) Identify three significant sources of error in this investigation. ………………………………………………………………………………………………………. ………………………………………………………………………………………………………. ………………………………………………………………………………………………………. ………………………………………………………………………………………………………. ………………………………………………………………………………………………………. ………………………………………………………………………………………………………. …………………………………………………………………………………………………… [3] (v) Suggest how you would make improvements to reduce two of the sources of error identified in (a)(iv). ………………………………………………………………………………………………………. ………………………………………………………………………………………………………. ………………………………………………………………………………………………………. ………………………………………………………………………………………………………. …………………………………………………………………………………………………… [2]

6 (b) A scientist investigated changes in the mean width of stomata in the leaves of a plant growing in hot, dry conditions. The scientist measured the widths of stomata at different times of day, from dawn to midnight. Fig. 1.1 shows where the scientist measured the width of each stoma. Fig. 1.1 The scientist calculated the mean width of stomata for each time of day. The results are shown in Table 1.2. Table 1.2 time of day mean width of stomata / arbitrary units (au) dawn 86 morning 36 noon 10 evening 6 midnight 95

7 [TURN OVER Use the grid provided to plot a graph in an appropriate form to display the data shown in Table 1.2. [4] [Total: 17]

8 2 (a) A group of students were given two species of plants, Species A and Species B. Their teacher also shared that one species is classified as a shade plant while the other is classified as a sun plant. By measuring the rate of decolorization of DCPIP, describe how the students could design an experiment to investigate which species belongs to which category. You must use:  50 g of leaves from Species A and Species B,  5 cm3 of DCPIP solution,  blender,  50 cm3 cold extraction buffer solution,  capillary tubes,  aluminium foil,  card tent,  lamp which emits very little heat,  timer, e.g. stopwatch  ruler You may select from the following apparatus and use appropriate additional apparatus:  normal laboratory glassware e.g. test-tubes, beakers, measuring cylinders, graduated pipettes, glass rods, etc.  syringes. 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 diagram(s), if necessary  identify the independent and dependent variables  describe the method with the scientific reasoning used to decide the method so that the results are as accurate and repeatable as possible  include layout of results tables and graphs with clear headings and labels  use the correct technical and scientific terms  include reference to safety measures to minimise any risks associated with the proposed experiment. ………………………………………………………………………………………………................ ………………………………………………………………………………………………................ ………………………………………………………………………………………………................ ………………………………………………………………………………………………................ ………………………………………………………………………………………………................ …………………