Name: _______________________________________ Period #: _______________ Page #: _________
Photosynthesis Modeling
Helpful vocabulary
Matter: anything that has mass and takes up space.
Atom: smallest particle of matter (example: sodium (Na) and chlorine (Cl) are atoms).
Molecule: two or more atoms joined together (example: sodium and chlorine (NaCl)
combine to form table salt).
Photosynthesis: the process by which a green plant containing chlorophyll uses light energy
to convert CO2 (carbon dioxide) and H2O (water) into a simple sugar.
Chlorophyll: the green pigment in plants that captures the sun’s energy used in
photosynthesis.
Chloroplast: the part of a plant cell that makes chlorophyll and is the “home” of
photosynthesis.
Stomata: small openings on the surface of a leaf.
Reactant: a substance that takes part in and undergoes change during a reaction.
Product: a substance that is formed as the result of a chemical reaction.
Directions:
In this activity you will be modeling how a plant uses abiotic resources to create food. The
following steps will guide you through this process while determining the mathematical
model, or formula, that represents photosynthesis: (A + B + C → X + Y + Z).
Materials:
1 paper leaf
1 paper sun
6 green chips - carbon atoms (C)
24 orange chips - oxygen atoms (O)
24 blue chips - hydrogen atoms (H)
Procedure
1. The chips at your desk represent individual atoms. Using these chips you can you combine
atoms (chips) to make two different substances needed in photosynthesis. Move the chips
to make as many of these molecules as possible. What are the two substances that you
made?
________________________ & ________________________
2. CO2 (carbon dioxide) enters the leaf through the stomata. How many molecules of CO2
(carbon dioxide) did you make? _______ CO2 (carbon dioxide). This is the first part of the
formula (A).
3. H2O (water) enters the leaf through the stomata and roots. How many molecules of H2O
(water) did you make? _______ H2O (water). This is the second part of the formula (B).
4. These reactions occur in the presence of sunlight. This is the third part of the formula (C).
Now that we have values for all of the variables let’s put the formula together:
__________________________ + __________________________ + __________________________
(A: number and name of molecule)
(B: number and name of molecule)
(C)
5. Place all of your molecules inside the leaf; keeping them paired as H2O (water) and CO2
(carbon dioxide) molecules.
Draw a sketch here:
6. As sunlight is absorbed, the light breaks apart H2O (water) molecules in the leaf. Add the
sun to the sketch above. Separate your H2O (water) molecules back into individual atoms.
How many molecules of O (oxygen gas) do you have? _______ O (oxygen gas). This is the
sixth part of the formula (Z). These O molecules leave the leaf through the stomata.
7. Now let’s look at the part of photosynthesis that actually creates the simple sugar.
Draw a sketch here:
8. Pair the remaining H (hydrogen) atoms into H2 (hydrogen gas). We have to do this
because hydrogen, like Oxygen, is a diatomic molecule. How many molecules of H2
(hydrogen gas) did you make? _______ H2 (hydrogen gas molecules). These H (hydrogen)
molecules power the rest of the food making process.
9. In order for the chloroplast to function the CO2 (carbon dioxide) molecules must be
separated into groups of three. Arrange your molecules (chips) this way.
10. The CO2 (carbon dioxide) molecules each attract an H2 (hydrogen gas) molecule to
create a chain. Place ONE H2 (hydrogen gas) molecule at the end of each CO2 (carbon
dioxide) molecule. Move your atoms (chips) to create this pairing.
11. The paring in step10 forces ONE O (oxygen) atom to be removed from the molecule.
Remove ONE O (oxygen) atom from each chain.
12. You now have pairs of H2 (hydrogen gas) molecules and O (oxygen) atoms which are not
part of the chain. The structure and chemical components of a chloroplast allows H2
(hydrogen gas) molecules to pair up and join with one O (oxygen). When this pairing
happens what molecule has been created _________________________________. This is the
fifth part of the formula (Y). These molecules leave the leaf through the stomata. This
process is called ____________________________.
Draw a sketch here:
13. Look at the atoms (chips) that remain on the leaf.
How many C (carbon) atoms? _____
How many H (hydrogen) atoms? _____
How many O (oxygen) atoms? _____
What chemical can you make with these atoms? _____________________________________
Which component of the formula does this represent? ______________
14. What is the full formula for photosynthesis?
____________ + ____________ + _____________ → ____________ + ____________ + ____________
(A)
(B)
(C)
(X)
(Y)
(Z)
Conclusions/Homework:
15. Now look at ALL of the atoms (chips) in and around the leaf.
How many C (carbon) atoms? _____
How many H (hydrogen) atoms? _____
How many O (oxygen) atoms? _____
16. Think about the amount and type of atoms you had at the start of the activity. Are there
the same number of atoms at the end of the activity? __________
17. The answer to numbers 15 and 16 allow you to make a claim about the number and
types of atoms and molecules that occur in a leaf before and after photosynthesis occurs.
Write you claim here:
_______________________________________________________________________________________
_______________________________________________________________________________________
What is your evidence for this claim?
_______________________________________________________________________________________
_______________________________________________________________________________________
What is your reasoning for this claim? Use the evidence above to explain your reasoning:
_______________________________________________________________________________________
______________________________________________________________________________________
18. Refer back to #13. Copy the data here:
How many C (carbon) atoms? _____
How many H (hydrogen) atoms? _____
How many O (oxygen) atoms? _____
What simple sugar can you make with these atoms? ____________________________________
Is this simple sugar a
reactant
or
product
(circle one)?
19. What is the full formula for photosynthesis?
____________ + ____________ + _____________ → ____________ + ____________ + ____________
(A)
(B)
(C)
(X)
(Y)
(Z)