biology p2 soln.pdf

Uganda Certificate of Education SCORING GUIDE BIOLOGY 553/2 BIOLOGY Paper 2 © 2024 Uganda National Examinations Board 2024 UGANDA NATIONAL EXAMINATIONS BOARD Paper 2 Practical Hypothesis: Frequent sickness of Mary’s child is due to absence of required nutrients in food samples A and B. Qn. 1  Solutions A and B.  Iodine solution.  Benedict’s solution.  Dilute hydrochloric acid.  Dilute Sodium hydroxide.  DCPIP.  Copper(II) sulphate solution.  Heat source.  Test tubes and droppers. Aim: To investigate the nutrients present in the food samples A and B. 2 List of Apparatus, reagents, solutions and Materials used: EXPECTED RESPONSES 553/2 Procedure, Observations/ data presentation  Iodine solution.  Benedict’s solution.  Dilute hydrochloric acid.  Dilute Sodium hydroxide.  DCPIP.  Copper(II) sulphate solution.  Heat source.  Test tubes and droppers. Procedure, Observations/ data presentation | | | | Procedure | Sample | Observations | Deductions | To 1 cm3 of food sample add 2 drops of Iodine solution | A | Cloudy/turbid/milky solution turns black/ blue-black | Starch present | | B | Cloudy/turbid/milky solution turns black/blue-black | Starch present | To 1 cm3 of food sample add 1 cm3 of Benedict’s solution and boil | A | Cloudy/turbid/milky solution turns blue and the blue colour persists. | Reducing sugars absent | | B | Cloudy/turbid/milky solution turns blue and the blue colour persists. | Reducing sugars absent | To 1 cm3 of food sample add 1 cm3 of dil HCl