Waec Model Questions Vol1 2023 Biology Question 3

A student is determining the carbohydrate content of a commercial cereal sample using colour reactions. The procedure is: 1. Accurately weigh 2.00 g of powdered cereal into a beaker. 2. Add 50 mL of distilled water, heat gently and stir until the material is completely dissolved. 3. Filter the solution and collect the clear filtrate. 4. Take 10 mL of the filtrate, add 2 mL of iodine solution and record the colour observed. 5. Take a separate 5 mL aliquot of the filtrate, add 5 mL of Benedict’s solution, heat in a water‑bath for 5 minutes and compare the colour of the resulting solution with the following standard glucose solutions (prepared in 100 mL distilled water): • 0.2 g glucose per 100 mL – colour faint yellow • 0.4 g glucose per 100 mL – colour orange‑red • 0.6 g glucose per 100 mL – colour brick‑red • 0.8 g glucose per 100 mL – colour deep red The student’s sample gives the same colour as the 0.4 g / 100 mL standard. Assume that all the carbohydrate present in the cereal is glucose‑equivalent and that the iodine test is only qualitative. Answer the following questions.