1. TESTING FOR DIFFERENT SUGARS Biochemical tests using Benedict's solution for reducing sugars and non-reducing sugars and iodine/potassium iodide for starch.

2. Using the Lab Skills Book  We have to record our A-level practicals that we do in a fashion that suits professional scientific work:  Using a green book: Your name, Biology Lab Book Year 12.  Each practical will have these sections: Title, Aim, Equipment, Brief method, Risks, Results, Conclusions.  We have an a core practical coming up so today we will practise using them.  Title today: Testing for Sugars and Starch. Outcome: Use Biochemical tests including Benedict's solution for reducing sugars and non- reducing sugars and iodine/potassiu m iodide for starch.

3. I have a collection of diffferent carbohydrates  You are going to collect these carbohydrates, 3 tubes of each.  You need to complete the tests in the order provided. 1. What do you think the aim is? (2 minutes) 2. Read through the method. Briefly describe the potential risks involved. (5 Minutes) 3. Draw a results table. Consider that we know the names of the carbohydrates, we just need to know whether they are reducing sugars, non-reducing suagrs or starch present. (5 Minutes) 4. Complete the practicals (15 minutes)

4. Methods: I have a collection of carbohydrates Test 2: Benedicts Test for Reducing Sugars  To 2cm3 of the unknown solution, add an equal volume of Benedicts reagent  Heat in a water bath which is gently boiling for 5 minutes.  If a reducing sugar is present, the solution will turn insoluble red/orange.  (Benedicts reagent is copper sulphate and will react to make copper oxide when a reducing sugar is present) Test 3: Benedicts Test for Non-Reducing Sugars  To 2cm3 of the unknown solution, add an equal volume of Hydrochloric acid (this will break down the glycosidic bond)  Add a small volume of sodium hydrogen carbonate solution.  Check with pH paper to ensure the solution is not acidic.  Add 2cm3 of Benedicts reagent  Heat in a water bath which is gently boiling for 5 minutes.  If a non-reducing sugar is present, the solution will now turn insoluble red/orange. Test 1: Testing for Starch  To 2cm3 of the unknown solution, add a few drops of brown Iodine Solution  If starch is present then the solution will turn a blue black colour

5. Conclusions: 1. Which substances are reducing sugars? 2. Which are non- reducing sugars? 3. Which tube contains starch (obvious?) 4. How could you use these tests to discover the contents of a mystery solution? (Paragraph answer) 5. Context: Who would find these tests useful? 6. How could these tests also be quantitative as well as qualitative? (i.e. how could they tell us how much reducing or non reducing sugar ir starch is present in a substance?) Outcome: Use Biochemical tests including Benedict's solution for reducing sugars and non- reducing sugars and iodine/potassiu m iodide for starch.