NYJC 2024 H2 Biology P4 (QP)

9744 / H2 Biology / 04 NANYANG JUNIOR COLLEGE PRELIMINARY EXAMINATIONS Higher 2 CANDIDATE NAME CLASS BIOLOGY 9744/04 Paper 4 Practical 22 August 2024 Candidates answer on the Question Paper Additional Materials: As listed in the Confidential Instructions 2 hour 30 minutes READ THESE INSTRUCTIONS FIRST Write your name and CT 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, highlighters, glue or correction fluid. DO NOT WRITE IN ANY BARCODES. 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. Shift Laboratory 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. For Examiner’s Use 1 2 Total This document consists of 19 printed pages and 0 blank pages. [Turn over H

2 9744 / H2 Biology / 04 Answer all the questions. 1 J1 is a slide of a stained transverse section through a plant leaf. (a) (i) Draw a large plan diagram of the whole section on J1. Use a sharp pencil. Use one ruled label line and label to identify the epidermis. [5] (ii) The leaf section on J1 is from a plant that lives at high altitudes in very cold conditions. In the winter the ground is often frozen and plants are unable to take up water. Suggest one observable feature of the leaf section on J1 which enables it to survive these conditions. [1]

3 9744 / H2 Biology / 04 (iii) Observe the cells in the epidermis of the section on J1. Select a line of four adjacent cells that make up this tissue. Each cell must touch at least one of the other cells. • Make a large drawing of this line of four cells. • Use one ruled label line and label to identify the cell wall of one cell. [5]

4 9744 / H2 Biology / 04 (b) Fig. 1.1 is a photomicrograph of a stained transversed section through a different type of leaf from J1. Fig. 1.1

5 9744 / H2 Biology / 04 Identify three observable differences between the leaf section on J1 and the leaf section in Fig. 1.1. Record these three observable differences in Table 1.1. Table 1.1 Feature J1 Fig 1.1 [3]

6 9744 / H2 Biology / 04 (c) Fig. 1.2 is the same photomicrograph as that in Fig. 1.1, with the line X – Y drawn across its width. Fig. 1.2 In Fig. 1.2 the line X – Y is drawn across the width of the leaf. Use the line X – Y and the scale bar to calculate the actual width of the leaf. Show your working. actual width of leaf = …………………………….. [4]

7 9744 / H2 Biology / 04 Several studies have suggested that shifts in stomatal densities in pine leaves can be attributed to rising atmospheric carbon dioxide concentrations and climate change. A student decided to investigate the differences by observing 6 pine leaves from the Pinus genus under a light microscope. Table 1.2 shows the student’s results. Table 1.2 P. taeda P. ponderosa Mean stomatal density 114.64 ± 10.51 52.11 ± 3.35 The formula for t-test is: (i) Complete the calculation to find the value of t for the stomatal densities. Show your working. t = ____________________ [3] Key to symbols s = standard deviation x = mean n = sample size (number of observations) v = degrees of freedom

8 9744 / H2 Biology / 04 Table 1.2 shows the critical values for the t-test. Table 1.2 (ii) State and explain the meaning of the results. [2] [Total: 23]

9 9744 / H2 Biology / 04 2 You are required to investigate the effect of concentration of hydrochloric acid (independent variable) on the rate of diffusion. The investigation involves placing agar cubes containing an indicator into dilute hydrochloric acid. As the acid diffuses into the agar cubes the indicator changes colour. You are provided with the materials shown in Table 2.1. Table 2.1 labelled contents hazard volume / cm3 H 1.0 mol dm–3 hydrochloric acid irritant 100 A agar none – W distilled water none 60 It is recommended that you wear suitable eye protection. If H comes into contact with your skin, wash it off immediately under cold water. You must not touch the agar with your hands. Use the blunt forceps and paper towel to handle the agar. You will need to carry out a trial test (step 1 to step 4) before you start your investigation.

10 9744 / H2 Biology / 04 Read step 1 to step 4 before proceeding. 1. Cut 3 cubes from the agar, A, as shown in Fig. 2.1. Each cube should be approximately 5 mm × 5 mm x 5 mm but they must all have the same dimensions. Cut the cubes from A on the white tile provided. Fig. 2.1 2. Put 10 cm3 of 1.0 mol dm–3 hydrochloric acid, H, into a beaker. 3. Put the 3 cubes you cut in step 1 into the beaker containing H, using blunt forceps. Start timing. As the acid diffuses into the agar cubes they change colour. The end -point is reached when the blue-green colour disappears and the whole cube has changed colour from blue-green to pink. Putting the beaker on the white card provided may help you to see the colour changes more clearly. 4. Measure the time taken for each cube to reach the end-point and record the times in (a)(i). If any cube remains blue-green after 3 minutes, record as ‘more than 180’. (a) (i) Record your results in an appropriate table. [2]