Download Modeling Photosynthesis: The Fruit-Loop Lab

Modeling Photosynthesis: The Fruit-Loop Lab
You may be familiar with the law of physics that states that matter and energy cannot be created or
destroyed – they merely change from one form to another. This law also applies to the process of
photosynthesis. You have learned that plants are called producers because they posses the ability to
manufacture their own food from carbon dioxide (CO2), water (H2O), and light energy from the sun. Light
energy from the sun is used to break up the molecules of CO2 and H20 then helps rearrange the atoms of
carbon, oxygen, and hydrogen to form sugar (C6H12O6) and oxygen (O2). Sugar molecules are energy
storage molecules, which “trap” the sun’s energy in their molecular bonds. When an organism needs
energy for cellular processes, this sugar is broken down to release that stored energy in the process of
cellular respiration. You will see how the raw materials are used to make sugar in this simple
demonstration using Fruit-Loops to represent atoms and molecules. Follow the steps to show how carbon
dioxide, water, and light will give you sugar and oxygen through the process of photosynthesis.
Step 1 Use the key chart below to record the colors that you will use to represent each type of atom.
Color the corresponding pieces to represent the colors you choose for your atoms.
Atom
Number of Pieces
Oxygen
18
Hydrogen
12
Carbon
6
Color of Cereal
Step 2 Obtain the colored cereal pieces. Count out 18 of your oxygen atoms and place them aside in a
pile. Count out 12 of your hydrogen atoms and place them aside in another pile. Lastly, count out
6 of your carbon atoms and place them aside in a third pile.
Step 3 Assemble the raw materials needed for photosynthesis. For a chemical reaction like
photosynthesis, the materials you start with are called the reactants.
•
•
•
Make a carbon dioxide molecule, CO2, by putting together one carbon piece and two oxygen
pieces.
Make a water molecule, H2O, by putting together two of your hydrogen pieces and one oxygen
piece.
Continue to make carbon dioxide and water molecules until all the cereal pieces are used up.
Hint: You should not have any cereal pieces left over. If you are having problems with too many or not
enough pieces then recount the number of pieces represented for each atom.
6
Step 4 How many total molecules of carbon dioxide were you able to make? ______
6
How many total molecules of water were you able to make? ______
Step 5 Draw diagrams of all the “cereal” molecules you created below. Use colored pencils to make
circles to represent each piece of cereal.
Diagram of Reactants
Carbon Dioxide
Water
Step 6 To provide the energy needed to break the bonds that hold the atoms together in the carbon dioxide
and water molecules, carefully mix up the pieces with your hands.
By mixing up the pieces with your hands, what part of the photosynthesis process does this
represent? Hint: You are using energy to mix up the pieces with your hands so this part of
photosynthesis process involves a type of energy.
It represents light energy. “Light energy from the sun is used to break up the
molecules of CO2 and H20…”
Step 7 Once the bonds holding the molecules are broken, the atoms are then rearranged by the same type
of energy above to form products.
•
•
Use the same cereal pieces to make a simple sugar molecule called glucose, C6H12O6, by putting
together 6 carbon atoms, 12 hydrogen atoms, and 6 oxygen atoms.
With the remaining cereal pieces, put together pairs of oxygen atoms, O2.
1
6
______
Step 8 How many total molecules of sugar were you able to make? ______
How many total molecules of oxygen were you able to make?
Step 9 Draw diagrams of all your “cereal” molecules below. Use colored pencils to make circles to
represent each piece of cereal.
Diagram of Products
Sugar
Oxygen
Step 10 Complete the photosynthesis equation below by writing in the correct number of molecules used.
6
6
______ CO2 + ______ H2O + Light
chlorophyll
1
6
______ C6H12O6 + ______ O2