2023 CJC Prelim H2 Bio 9744 P4.ANS (for sharing)

9744 / 04 / Prelim Examination / 2023 NAME: ________________________________________ CLASS: _________ INDEX: __________ CATHOLIC JUNIOR COLLEGE JC2 PRELIMINARY EXAMINATIONS Higher 2 BIOLOGY 9744 / 04 Paper 4 Practical 25 August 2023 2 hours 30 min Candidates answer on the Question Paper Additional Materials: READ THESE INSTRUCTIONS FIRST Write your index number and name 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 a HB pencil for any diagrams or graphs. Do not use staples, paper clips, 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. 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. This document consists of XX printed pages and X blank page. [Turn over Shift Laboratory For Examiner’s Use 1 2 3 TOTAL MARKING SCHEME

2 9744 / 04 / Prelim Examination / 2023 Answer all questions. 1 During photosynthesis in leaves, carbon dioxide enters through stomata and diffuses through intercellular air spaces to the mesophyll. Leaf discs submerged in solution can be used to investigate photosynthesis. To investigate the effect of carbon dioxide concentration on the rate of photosynthesis in leaf discs, you will: • prepare different concentrations of sodium hydrogencarbonate solution, as a source of dissolved carbon dioxide. • measure the rate of photosynthesis by recording the time taken for submerged leaf discs to reach the surface due to the build-up of oxygen in the air spaces. You are provided with: • 30 cm3 of 10.0 g dm–3 sodium hydrogencarbonate solution, labelled H1 • distilled water, labelled W • fresh, green leaves from plant species A, in a Petri dish labelled A (a) Carry out a serial dilution of the 10.0 g dm –3 sodium hydrogencarbonate solution, H1, to reduce the concentration of the sodium hydrogencarbonate solution by half between each of three successive dilutions, to give H2, H3 and H4. You are required to make up a sufficient volume of each concentration of sodium hydrogencarbonate solution in the specimen tubes provided so that, once the serial dilution has been completed, there is at least a volume of 10 cm3 for each solution. (i) Complete Fig. 1.1 on page 3 to show how you will carry out your ser