1. Testing for Biological Macromolecules
Biology
Ms. Haut

2. Benedict’s Test for Monosaccharides
Add 1 ml (10 drops) of Benedict’s solution to the test tube.
Add 8 drops of sample solution to a test tube.
Heat the mixture in a boiling water bath for 10 minutes.
                                                      
negative positive

4. Initial Color Final Color

5. Lugol’s (Iodine) Test for Polysaccharide
Place a 1 mL of the sample solution into a test tube.
Add 5 drops of Lugol’s solution (IKI) to the test tube.
Swirl the test tube to mix.
If the solution turns bluish-black in color, you will know that polysaccharide is present.
                                                      
positive negative

6. http://www. webexhibits
Note the change of the iodine to black on the potato (right) but not the apple (left). Potato contains starch, but apple does not.

7. Biuret Test for Proteins
Add 1 ml (10 drops) of Biuret reagent to the test tube.
Put 1 ml of sample in a test tube.
If the solution turns purple in color, you will know that protein is present.
Positive

9. Paper Test for Fats
Using the spatula, smear some fat onto a piece of plain paper. Ensure that the paper is not glazed or waxed.
Hold the paper up to the light or window, attempting to look through the spot formed by the fat.
If a greasy spot remains after the paper dries, fats are present.

10. Sudan III Test for Fats Place 1 ml of your sample into a test tube.
Place 1 drop of Sudan III solution into your sample.
Swirl the test tube to mix.
If the solution stains red, fats are present.