Name: ___________________________________
Period: ______
Modeling Photosynthesis & Cellular Respiration: The Big Picture
Use your notes and prior knowledge of plants and animals to complete the activity and answer the questions below.
Activity 1: Modeling Photosynthesis
1. Obtain a set of modeling molecules. Each set contains the following:
a. 8 carbon atoms (black spheres with 4 pegs)
b. 15 hydrogen atoms (white spheres with 1 peg)
c. 20 oxygen atoms (blue spheres with 2 pegs)
d. 40 covalent bonds (white tubes)
2. Build one water molecule (H2O) and one carbon dioxide molecule (CO2). Use your molecules as a guide to draw
the structural formula in the table below.
3. Now make 5 more water molecules and 5 more carbon dioxide molecules. Put away any leftover atom and
bond model pieces because you will not need them.
4. Model the formation of a glucose molecule (C6H12O6) by the chemical reaction between a carbon dioxide
molecule and a water molecule by:
a. “Breaking the bonds of the reactant molecules” by removing the white tubes from the models of all 12
molecules (water and carbon dioxide) you just built.
b. Reassembling the atoms and bonds from the “reactant molecules” to form as many glucose molecules
as you can. Hint: the basic structure of glucose is a ring made from 5 carbon atoms and 1 oxygen atom.
5. If you have any bonds and atoms left over, use these to create as many other molecules as you can. Hint: the
chemical formula for oxygen gas is O2.
6. Look at the molecules you have made and complete the chemical equation below the table that describes the
production of glucose via photosynthesis.
7. Draw the structural formula for a glucose molecule and an oxygen molecule in the table.
Q1. Table of Photosynthesis Reactants and Products
Chemical Formula
Structural Formula
Water (H2O)
Carbon dioxide (CO2)
Glucose (C6H12O6)
Oxygen (O2)
Q2. Chemical equation for photosynthesis:
___________ + ____________ + ____________  _____________ + ______________
Q3. (Use the NAMES of the molecules) According to your equation, the process of photosynthesis uses
____________________, _____________________, and _____________________ to produce
_____________________ and _____________________.
Q4. What type of energy is used in photosynthesis?
Q5. Photosynthesis typically occurs in what type of organism?
Q6. Where are CO2 and O2 found in our environment?
Q7. Given what you know about plants, why does your position for CO2and O2 in the equation make sense?
Q8. Interpret the chemical reaction - what is the overall purpose of photosynthesis?
Activity 2: Modeling Cellular Respiration
1. Model the breakdown of a glucose molecule (C6H12O6) by the chemical reaction between a glucose and oxygen
molecules by:
a. “Breaking the bonds of the reactant molecules” by removing the white tubes from the models of all 7
molecules (glucose and oxygen) you just built.
b. Reassembling the atoms and bonds from the “reactant molecules” to form as many carbon dioxide and
water molecules as you can. Hint: the chemical formula for oxygen gas is O2.
2. Look at the molecules you have made and complete the chemical equation below that describes the breakdown
of glucose via cellular respiration.
Q9. Chemical equation for cellular respiration:
___________ + ____________  _____________ + ______________+ ____________
Q10. (Use the NAMES of the molecules) According to your equation, the process of cellular respiration uses
____________________ and _____________________ to produce _____________________,
_____________________, and _____________________.
Q11. In cellular respiration, chemical energy is released from ____________ molecules and transferred to
____________ molecules, which cells can use to provide energy for cellular processes.
Q12. Was it difficult to rearrange your pieces to produce the equation for cellular respiration? Why or why not?
Q13. Cellular respiration occurs in both plants and animals. Given what you know about animals, why does your
position for CO2 and O2 in the equation make sense?
Q14. Interpret the chemical reaction - what is the overall purpose of cellular respiration?
Q15. What are the two main differences between the chemical reaction for photosynthesis and the chemical
reaction for cellular respiration?
Q16. Complete the blanks and label the parts in the photosynthesis and cellular respiration cycle below.
(Use the terms: autotroph, heterotroph, chloroplast, mitochondria, photosynthesis, cellular respiration, oxygen,
carbon dioxide, solar energy, ATP/usable energy, glucose, water)
Extension Questions – Please answer these questions in complete sentences!!
1. Cellular respiration occurs in BOTH plants and animals. Why do plants need cellular respiration?
2. Plants produce carbon dioxide as a product of cellular respiration. But you know that plants release oxygen, not
carbon dioxide. Develop a logical argument for how this is possible. HINT: Think about both chemical reactions
and the speeds at which they could occur.
3. Plants can make their own food through photosynthesis and then break it down for usable energy through the
process of cellular respiration. Analyze how your life might be different if you could make your own food
through photosynthesis.