Biology Lab
Fill in the table below with the results from the monosaccharide test experiment, and your conclusions based on those results.
Results Monosaccharide Test
Solution Initial Color Color with Benedict’s Solution Color After Heating Monosaccharide?
glucose solution
water
sucrose solution
fructose solution
Benedict’s solution is added to white grape juice and heated. The color changes from blue to orange. Based on this result, what biological molecules are present in the
white grape juice?
Benedict’s solution can be used to distinguish between monosaccharides and disaccharides. Why?
Benedict’s solution cannot be used to distinguish between two monosaccharides. Why?
Experiment 2: Starch Test
Fill in the table below with the results from the starch test experiment.
Results Starch Test
Solution Initial Color Color with Iodine Solution
starch solution
water
Iodine solution is added to a chocolate chip cookie solution. The color changes to purple. Based on this result, what biological molecules are present in the chocolate
chip cookie solution?
What is the relationship between monosaccharides and starches?
Experiment 3: Lipid Test
Fill in the table below with the results from the lipids test experiment.
Results Lipids Test
Solution Initial Color Color with Sudan Solution
corn Oil
water
What results would you expect from a sudan test of chicken soup?
What is the size difference between fat polymers and starch and protein polymers?
Experiment 4: Protein and Peptides Test
Fill in the table below with the results from the protein and peptides test experiment..
Results Protein and Peptides Test
Solution Initial Color Color with Biuret Solution
egg albumin solution
egg albumin solution plus HCl plus pepsin
water
What could account for the differences (if any) between the results for the Biuret test for the egg whites with HCl and pepsin versus the egg whites alone?
What results would you expect from a biuret test of chicken soup?
Experiment 5: Food Contents Test
Fill in the table below with the results from the food experiment.
Results Food Test
Food Reducing sugars Starch Lipids Protein
potato juice
onion juice
whole milk
skim milk
Although we consider it non-fat, skim milk actually has very low levels of lipids. Therefore, it should test positive with Sudan solution. Why is the Sudan test for
skim milk negative?
Lactose is a sugar, so why isn’t milk positive for the Benedict’s test?
