Question

Biuret reagent tests for proteins. There are other reagents that test for other macromolecules. For carbohydrates, Benedict’s reagent tests for simple sugars and iodine (IKI) tests for starch. For lipids, a simple grease spot test using a brown paper bag can be performed, where fatty substances will cause the spot to be translucent when held up to a light.

Record the expected colors of solutions of the following substances when tested with these reagents and explain your hypotheses:

            Bread:                         Biuret:

                                    Benedict’s:

                                    Iodine:

                                    Grease Spot:

Explanation of hypothesis:

            Ground Beef: Biuret:

                                    Benedict’s:

                                    Iodine:

                                    Grease Spot:

                                    Explanation of hypothesis:

            Soda:               Biuret:

                                    Benedict’s:

                                    Iodine:

                                    Grease Spot:

                                    Explanation of hypothesis:

            Diet Soda:       Biuret:

                                    Benedict’s:

                                    Iodine:

                                    Grease Spot:

                                    Explanation of hypothesis:

Answer 1

Bread is high in carbohydrates therefore it should show a positive Benedict's reagent test and a negative response for the rest

Ground beef is high in both protein and fat so it shows positive results for both Biuret and grease spot test and negative for the rest

Soda are high in sugar so should show a positive Benedict's reagent test and negative for the rest

Diet soda do not contain simple sugars instead have artificial sweeteners so it is negative for all the tests