RVHS 2023 JC2 H2 Prelim P4 Answers

RIVER VALLEY HIGH SCHOOL JC 2 PRELIMINARY EXAMINATION CANDIDATE NAME CENTRE NUMBER S CLASS INDEX NUMBER H2 BIOLOGY 9744/04 Paper 4 Practical 24 Aug 2023 Candidates answer on the Question Paper. 2 hours 30 minutes Additional Materials: As listed in the Confidential Instructions. READ THESE INSTRUCTIONS FIRST Write your Centre number, index number, class 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 an HB pencil for any diagrams or graphs. Do not use staples, paper clips, glue or correction fluid. DO NOT WRITE ON 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. 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. Shift Laboratory For Examiner’s Use 1 2 3 Total This document consists of 21 printed pages and 3 blank pages.

2 River Valley High School 2023 JC2 Preliminary Examination H2 Biology 9744/04 Answer all questions. 1 Cells contain enzymes that catalyse metabolic activities. Some of these reactions release carbon dioxide. A scientist engineered a new strain of yeast, BY62, which he believes has higher rates of metabolic activities. You will investigate the release of carbon dioxide from mixtures of yeast and carbohydrate, one comprising a common yeast strain, Y , and the other comprising BY62. Each mixture is put into a dialysis (Visking) tubing. The dialysis tubing acts as a partially permeable membrane, allowing the carbon dioxide to diffuse out of the dialysis tubing. You are required to: • perform serial dilution to obtain different concentrations of P • collect results and present it in a suitable table • estimate the concentration of carbon dioxide in BY62 mixture You are provided with: • 1 g dried yeast, in a test-tube labelled Y • 10.0 % glucose solution, in a container labelled S • Mixture containing carbon dioxide produc ed from BY62 and carbohydrate, in a container labelled P • bromothymol blue indicator solution, in a container labelled B • dialysis tubing, in a beaker of distilled water labelled D • distilled water, in a beaker labelled W If any solution comes into contact with your skin, wash off immediately under tap water. Suitable eye protection should be worn. To test for the release of carbon dioxide, a sample of the water surrounding the dialysis tubing is added to drops of an indicator, B. Fig. 1.1 shows the effect of increasing concentration of carbon dioxide on the colour of B . Yellow is the end-point. BLUE blue-green