ACSI Instructions (P3 Preparation List) - for Y4 Exp Bio Prelim 2024

2024 YEAR 4 EXPRESS BIOLOGY PRELIMINARY EXAMINATION Paper 3 Confidential Instructions Question 1 No. Materials and Apparatus for each student Quantity 1 [C][MH] 1% hydrogen peroxide solution in bottles labelled H, provided at room temperature about 200 cm3 2 celery extract in a capped plastic tube, labelled celery extract, provided at room temperature (see Preparation of materials) about 15 cm3 3 distilled water in a small beaker labelled W, provided at room temperature about 100 cm3 4 empty 250 cm3 beaker labelled For waste 1 5 small paper discs in a Petri dish 20 - 25 6 10 cm3 measuring cylinder 1 7 stopper to fit test-tube 1 8 glass rod 1 9 forceps 1 10 small plastic container 1 11 standard test-tube 5 12 long test-tube 1 13 test tube rack 1 14 ruler with mm scale 1 15 permanent marker 1 16 stop-watch 1 17 paper towels 10 18 safety googles 1 19 disposable gloves 1 pair Question 2 and 3 No additional materials required.

Preparation of materials H should be made from a fresh stock solution as close to the time of the exam as possible. Materials Preparation Celery extract • Use fresh stalks of celery (Apium graveolens). • Homogenise the celery stalks in a food processor to release the juice. • Filter the juice through muslin or similar material to remove the solid material. • Provide about 15 cm 3 in a capped plastic tube labelled celery extract for each student. Note This should be made from a fresh stock solution as close to the time of the exam as possible. Before the exam test the catalase activity of the celery extract. Soak one paper disc in the celery extract. Put the soaked paper disc into the bottom of a standard test-tube. Pour in 18 cm3 of 1% hydrogen peroxide solution; the disc should take between 10 to 60 seconds to rise to the surface. If the time taken is less than 10 seconds or more than 60 seconds, adjust the concentration of the hydrogen peroxide solution accordingly. Paper discs • Paper discs (6 mm in diameter) can be prepared from filter paper using a standard stationery hole puncher. • Provide about 20 – 25 discs in a Petri dish per student. W • Distilled water in a small beaker labelled W. • Dispense about 200 cm3 in a beaker for each student. H *Note: [C][MH] • Prepare 1% hydrogen peroxide solution. • Dispense about 200 cm3 of hydrogen peroxide in bottles labelled H for each student.