Waec Model Questions Vol1 2020 Biology Question 3

You are required to determine the carbohydrate content of an unknown fruit sample using the Benedict’s test. The procedure you followed was: 1. Weighed 5.00 g of the fruit and macerated it in a mortar. 2. Added 50 mL of distilled water and boiled the mixture for 5 minutes to extract soluble sugars. 3. Cooled the extract and filtered it into a 100 mL volumetric flask and made up to the mark with distilled water. 4. To 10.0 mL aliquots of the extract, added Benedict’s reagent and heated in a boiling water bath for 5 minutes. 5. The colour of the precipitate was compared with a standard colour chart. Standard glucose solutions (prepared in 100 mL water) gave the following volumes of Benedict’s reagent that produced the same brick‑red colour as the unknown: | Standard glucose (g) | Volume of Benedict’s reagent (mL) | |----------------------|-----------------------------------| | 0.5 | 2.0 | | 1.0 | 4.5 | | 1.5 | 7.0 | For the fruit extract, 5.20 mL of Benedict’s reagent produced the same colour. Using the data above, answer the following: