Molecules that Make Up Living Things
Name ____________________
Organisms are made up of different molecules. The main molecules are
water, carbohydrates, proteins, and fats (lipids). Each of these molecules is
found in foods that we eat and each has an important job for the body. In
this lab, you will learn how to conduct a chemical test to determine which of
these compounds are found in different food samples.
A. Monosaccharide- A type of carbohydrate
1. How many sugar units are monosaccharide composed of? ____
2. What elements make up monosaccharides? ___________
3. How does the body use monosaccharides? ___________
4. Here is how you can test foods to see if they contain
monosaccharides:
a. Place a small sample (about 1 cm) of food (a light
liquid is best) in a test tube.
b. Put 10 drops of Benedict’s solution in the test tube.
c. Place the test tube in a hot water bath for about 2
minutes. WEAR SAFETY GOGGLES WHILE
HEATING TEST TUBES!!!!!!!
d. A color change to orange, rust, or yellow indicates there
are monosaccharides in the food sample.
e. Let the test tubes cool and then put materials down the
sink and clean the test tubes.
5. Choose 5 food samples to test for monosaccharides. Make a
data table to record your results:
6. If you needed fast energy, which of the foods you tested would
provide you with the monosaccharides required for this fast
energy? _____________________________________
B. Disaccharides- Another type of carbohydrate.
1. How many sugar units are disaccharides composed of?_____
2. What elements make up disaccharides? _________
3. How does the body use disaccharides? ____________
4. There is no chemical test for disaccharides.
5. Table sugar (white granulated sugar) is an example of a
disaccharide. List some foods that contain a lot of
disaccharides: _________________________________
C. Polysaccharides (starches)- ANOTHER TYPE OF
CARBOHYDRATE!!
1. How many sugar units are polysaccharides composed of? ____
2. What elements make up polysaccharides? ________
3. How does the body use polysaccharides?_________________
4. Here is how you can test foods to see if they contain
polysaccharides (starches):
a. Place a small sample of food in a container.
b. Put a drop of iodine on the food sample.
c. Wait 1-2 minutes. A color change to blue or black
indicates there are polysaccharides in the food sample.
5. Choose 5 food samples to test for polysaccharides. Make a data
table to record your results:
6. If you needed slow, steady energy, which of the foods you
tested would provide you with the polysaccharides required for
this slow, steady energy? ___________________________
D. Lipids (Fats)
1. What elements make up fats? __________________
2. How does the body use fats? ___________________
____________________________________________
3. Here is how you can test foods to see if they contain fats:
a. Place a small sample of food on paper towel and let sit
for about 3 minutes.
b. Remove the food and see if there is a translucent spot
where the food was. If there is an “oil” spot the food
sample contains fat.
4. Choose 5 food samples to test for lipids. Make a data table to
record your results:
5. If you needed more insulation or padding, which of the foods
you tested would provide you with the lipids required for this?
____________________________________________
E. Proteins
1. What are the building units that compose proteins?________
2. What elements make up proteins?_________________
3. How does the body use proteins?__________________
4. Here is how you can test foods to see if they contain proteins:
a. Put a small sample of food in the container.
b. Place 10 drops of Buiret Reagent on the food and let sit
for 1 minute.
c. A color change from blue to purple (or lavender)
indicates the food contains protein.
5. Choose 5 food samples to test for proteins. Make a data table
to record your results:
6. If you needed materials for cell growth and cell repair, which of
the foods you tested would provide you with the proteins
required for this?_______________________________
__________________________________
F. Summarize things you learned from this lab?