health information management



Biological Molecules
Experiment-Specific Questions
Experiment 1: Monosaccharide Test
1. 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
  

  clear

  blue

  orange

  yes
water
  

  clear

  blue

  blue

no  
sucrose solution
  

  clear

  blue

  blue

  no
fructose solution
  
clear
  

  blue

  orange

  yes

1. 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?  monosaccharide

1. Benedict’s solution can be used to distinguish between monosaccharides and disaccharides. Why?  Monosaccharide will change the benedict’s solution from blue to orange when heated. Disaccharide will not change the benedicts change the color.

1. Benedict’s solution cannot be used to distinguish between two monosaccharides. Why?  The two monosaccharides bonded together and formed an disaccharide. Thus the disaccharide will not change the color. Experiment 2: Starch Test

1. 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
  

  clear

  purple
water
  
clear
  
green
  

1. 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?  Starch

1. What is the relationship between monosaccharides and starches?  The monosaccharides bind together and form long chains. The chains are called polysaccharides or starched. Experiment 3: Lipid Test

1. 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
  

  green
orange
  
water
  

  clear
Clear

  
 
1. What results would you expect from a sudan test of chicken soup?  A red color would be present if sudan was tested in chicken soup. The reason is because the fatty oil in chicken soup.  
1. What is the size difference between fat polymers and starch and protein polymers?  Fat polymers can vary in shape and length, starch are coiled, and protein polymers are round shaped.  
Experiment 4: Protein and Peptides Test
1. 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 
  

  clear

  purple
egg albumin solution plus HCl plus pepsin
  

clear 

  purple
water
  
clear
 
blue
 
 
1. 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?  Pepsin helps the digestive system. The pepsin is an enzyme that helps digest proteins in the stomach.  

1. What results would you expect from a biuret test of chicken soup?  The color to turn pink
 
Experiment 5: Food Contents Test
1. Fill in the table below with the results from the food experiment. Results Food Test
Food
Reducing sugars
Starch
Lipids
Protein
potato juice
  

  orange

  black

  clear

  purple
onion juice
  
orange
  

  green
clear
  

  purple
whole milk
  

  blue

  green

  orange

  purple
skim milk
  

 blue 

  green

  clear

  purple
 
1. 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?  Skim milk has fat removed from it therefore the test results are negative when tested with sudan.  

1. Lactose is a...