Undergraduate introductory biology students at the university level often struggle to trace movement of matter and energy through catabolic and anabolic processes in biological systems. A sequential guided simulation of cellular respiration and photosynthesis provides students an opportunity to actively model and visualize matter transformation and energy accumulation and degradation through the movement of molecular and energy “game pieces.” The activity was designed to help students generate a simplified outline of these two highly complex processes, while reinforcing the principles of conservation of matter and energy. My students participated in this activity during peer-led review sessions in an undergraduate, introductory, majors biology course (ca.150 students in 18 SI sessions over two semesters), but instructors could also easily adapt it for use in small lecture or laboratory classrooms, introductory cell biology, physiology, and ecology courses, or with high school students.

Keywords:
cellular respiration, photosynthesis, matter cycling, energy transformation, misconceptions, active learning, simulation

Introduction

Introductory biology student performance indicates that students struggle to accurately apply matter and energy transformation in photosynthesis and cellular respiration to biological systems across multiple scales (e.g., Wilson et al., 2006; Hartley et al., 2011; Parker et al., 2012). For example, when describing weight loss, students may state that fat is converted to energy (as ATP) or expelled from the body as sweat, and few can identify that lost mass is released as carbon dioxide (Wilson, 2006). Using diagnostic tests and student interviews, previous researchers have identified several other common misconceptions about photosynthesis and cellular respiration, summarized in Table 1. These misconceptions suggest that students frequently lack a general understanding of these two processes, even after exposure in high school and introductory college courses.

Table 1.
Summary of published common student misconceptions in cellular respiration and photosynthesis.
Cellular respiration misconceptions 
Matter is converted to energy or ATP during cellular respiration (glucose to ATP); Wilson et al., 2006, Hartley et al., 2011. 
Matter catabolized during cellular respiration is released as waste, such as urine or feces; Wilson et al., 2006. 
Cells can utilize glucose only to generate ATP; Oliviera et al., 2003. 
Photosynthesis misconceptions 
Mass gain observed during plant growth results from water uptake; Wilson et al., 2006. 
Mass gain observed during plant growth results from nutrient uptake; Wilson et al., 2006. 
CO2 is not responsible for mass gain observed during plant growth; Parker et al., 2012. 
Matter (CO2) is converted to ATP; Parker et al., 2012, Hartley et al., 2011. 
Sunlight is converted to matter (energy to sugars); Parker et al., 2012, Hartley et al., 2011. 
ATP generated in photosynthesis is used for cellular work; Parker et al., 2012. 
Autotrophs do not conduct cellular respiration; Wilson et al., 2006, Parker et al., 2012. 
Cellular respiration misconceptions 
Matter is converted to energy or ATP during cellular respiration (glucose to ATP); Wilson et al., 2006, Hartley et al., 2011. 
Matter catabolized during cellular respiration is released as waste, such as urine or feces; Wilson et al., 2006. 
Cells can utilize glucose only to generate ATP; Oliviera et al., 2003. 
Photosynthesis misconceptions 
Mass gain observed during plant growth results from water uptake; Wilson et al., 2006. 
Mass gain observed during plant growth results from nutrient uptake; Wilson et al., 2006. 
CO2 is not responsible for mass gain observed during plant growth; Parker et al., 2012. 
Matter (CO2) is converted to ATP; Parker et al., 2012, Hartley et al., 2011. 
Sunlight is converted to matter (energy to sugars); Parker et al., 2012, Hartley et al., 2011. 
ATP generated in photosynthesis is used for cellular work; Parker et al., 2012. 
Autotrophs do not conduct cellular respiration; Wilson et al., 2006, Parker et al., 2012. 
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One way instructors can address these misconceptions is through hands-on simulations, so students can visualize and summarize these two complex processes. A variety of resources are available for instructors to approach these concepts in college and high school biology classrooms, but many have significant disadvantages (summarized in Table 2). To directly target misconceptions, I developed a simulation activity in which students apply the principles of conservation of matter and energy while actively modeling the steps of cellular respiration and photosynthesis at the cellular level. This activity was designed for my introductory biology course for biology majors, which meets twice a week for 1:15 in a large lecture hall (ca.150–200 students). The majority of students in the course are freshmen and sophomores (80–90%), with most entering the course after taking only one high school biology class.

Table 2.
Summary and analysis of selected learning resources available for teaching cellular respiration and photosynthesis in the classroom.
Example resources:AdvantagesDisadvantages
Fisher Scientific (catalog # S98808 and # S02447), Molecular modeling kits Interactive and visual; ready to use; includes teacher guide and all necessary supplies. Cost of kit; lack of complexity and flexibility; some kits do not address energy transformation; some kits do not integrate both processes. 
Carolina Biological (item # 746500 and # 746478 ), Molecular modeling kits Interactive and visual; includes teacher guide and all necessary supplies. Cost of kit; lack of complexity and flexibility; some kits do not address energy transformation; do not integrate both processes. 
Science Take-out (sciencetakeout.com, Catalog # STO-122), Printout with worksheets and student handouts Interactive and visual; includes teacher guide and all necessary supplies. Cost of handouts; lack of complexity and flexibility; energy transformation not integrated in simulated activity. 
Cellular Respiration explored, Sim Bio, computer module Data driven; interactive with student questions and feedback; tested for effectiveness; relevant context. Substantial cost; computer access required; less flexible and more focus on process; does not integrate both processes. 
Videos—examples include BioFlix with Campbell, youtube videos Observe whole process with realistic molecular visualizations. Some videos are not interactive with student questions; do not specifically address energy and matter conversions; often do not integrate both processes. 
Case studies—such as sciencecases.lib.buffalo.edu/cs/files/cellular_respiration.pdf Relevant context for students; data driven; interactive with questions instructor materials. Focus on specifics of process and steps rather than matter/energy cycling; does not integrate the both processes. 
Example resources:AdvantagesDisadvantages
Fisher Scientific (catalog # S98808 and # S02447), Molecular modeling kits Interactive and visual; ready to use; includes teacher guide and all necessary supplies. Cost of kit; lack of complexity and flexibility; some kits do not address energy transformation; some kits do not integrate both processes. 
Carolina Biological (item # 746500 and # 746478 ), Molecular modeling kits Interactive and visual; includes teacher guide and all necessary supplies. Cost of kit; lack of complexity and flexibility; some kits do not address energy transformation; do not integrate both processes. 
Science Take-out (sciencetakeout.com, Catalog # STO-122), Printout with worksheets and student handouts Interactive and visual; includes teacher guide and all necessary supplies. Cost of handouts; lack of complexity and flexibility; energy transformation not integrated in simulated activity. 
Cellular Respiration explored, Sim Bio, computer module Data driven; interactive with student questions and feedback; tested for effectiveness; relevant context. Substantial cost; computer access required; less flexible and more focus on process; does not integrate both processes. 
Videos—examples include BioFlix with Campbell, youtube videos Observe whole process with realistic molecular visualizations. Some videos are not interactive with student questions; do not specifically address energy and matter conversions; often do not integrate both processes. 
Case studies—such as sciencecases.lib.buffalo.edu/cs/files/cellular_respiration.pdf Relevant context for students; data driven; interactive with questions instructor materials. Focus on specifics of process and steps rather than matter/energy cycling; does not integrate the both processes. 
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Prior to the simulation, students are introduced to the concepts of conservation of energy and matter, free energy, oxidation reactions, and the general steps of photosynthesis and cellular respiration (through a combination of lecture material, assigned readings, and/or online videos). In my course, the simulation is conducted in optional weekly supplementary discussion sessions (of approximately 5–20 students) led by undergraduate peer leaders. For training prior to the simulation, the instructor models the complete activity with the peer leaders to demonstrate how to lead the simulation in the classroom. Additionally, peer leaders are provided detailed instructions (as presented in Tables 5 & 6 and Figures 3 & 5) along with power point slides to help organize the session. Although the activity was designed for discussion sessions in a large introductory majors biology course, it could easily be modified for use as an instructor-led activity for small lecture sections or laboratories with either undergraduates or even high school students in AP biology. Additionally, instructors in physiology or ecology courses could integrate the simulation into broader contexts using organ system or ecosystem labels or images.

Materials

Packets containing laminated “game pieces” are provided to groups of 2–6 students (see Table 3 for contents and Figure 1 for a printable sheet of the pieces). Students also receive colored stickers to serve as “energy stickers.”

Table 3.
Contents of student simulation activity packets. Pieces can be printed and laminated for repeated use.
Molecular game pieceNumber of pieces
H2O 12 
O2 6 
CO2 6 
NAD+ 10 
FAD 2 
NADP 12 
Glucose 1 
G3P 2 
5 ATP 5 
ATP 10 
H+ 12 
H− 12 
Molecular game pieceNumber of pieces
H2O 12 
O2 6 
CO2 6 
NAD+ 10 
FAD 2 
NADP 12 
Glucose 1 
G3P 2 
5 ATP 5 
ATP 10 
H+ 12 
H− 12 
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Figure 1.
Simulation packet game pieces. The printed images can be used to generate laminated pieces for the simulation. The number of each piece required for the simulation is indicated in Table 3. For a printable version of this figure, please send an email request to lacesvec@georgiasouthern.edu
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Simulation packet game pieces. The printed images can be used to generate laminated pieces for the simulation. The number of each piece required for the simulation is indicated in Table 3. For a printable version of this figure, please send an email request to lacesvec@georgiasouthern.edu

Figure 1.
Simulation packet game pieces. The printed images can be used to generate laminated pieces for the simulation. The number of each piece required for the simulation is indicated in Table 3. For a printable version of this figure, please send an email request to lacesvec@georgiasouthern.edu
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Simulation packet game pieces. The printed images can be used to generate laminated pieces for the simulation. The number of each piece required for the simulation is indicated in Table 3. For a printable version of this figure, please send an email request to lacesvec@georgiasouthern.edu

Simulation Introduction

(About 10 Minutes)

To introduce the simulation, the peer leader informs students that small groups will conduct a highly simplified representation of photosynthesis and cellular respiration in which matter and energy are conserved (i.e., the same atoms and available energy are present at the beginning and end of each step).

To begin, the peer leader distributes simulation packets to groups of 2–6 students, introduces the packet contents, and explains how components of matter and energy will be represented throughout the simulation. It is important to note that H− represents a hydrogen atom with two electrons and H+ represents a single proton; together two of these pieces represent two hydrogen atoms. Energy accumulation and degradation is modeled through movement of colored energy stickers. Several common reactions (Table 4) that involve energy transfer are outlined prior to beginning the simulation, as they occur repeatedly.

Table 4.
Energy transformations for reactions common to cellular respiration and photosynthesis.
ReactionEnergy transferred in each reactionEnergy change
ADP + Pi → ATP 0.5 energy piece Endergonic 
ATP → ADP + Pi 0.5 energy piece Exergonic 
Electron carrier (oxidized) + H− + H+ → electron carrier (reduced) 2 energy pieces Endergonic 
Electron carrier (reduced) → electron carrier (oxidized) + H− + H+ 2 energy pieces Exergonic 
ReactionEnergy transferred in each reactionEnergy change
ADP + Pi → ATP 0.5 energy piece Endergonic 
ATP → ADP + Pi 0.5 energy piece Exergonic 
Electron carrier (oxidized) + H− + H+ → electron carrier (reduced) 2 energy pieces Endergonic 
Electron carrier (reduced) → electron carrier (oxidized) + H− + H+ 2 energy pieces Exergonic 
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General Instructions for Simulation

(About 75 Minutes in Total, Depending on Length Of Discussion)

To run the simulation, the peer leader guides students through photosynthesis and cellular respiration in two steps each (the light reactions, the Calvin cycle, the catabolic steps of cellular respiration, and oxidative phosphorylation). The same general process occurs for each step in the simulation (outlined in Figure 2). First, the peer leader leads an introductory, large-group discussion to identify the primary purpose of the two presented steps in photosynthesis and respiration. Next, the peer leader presents formulas that outline each transformation and guides students through active simulation of the step in small groups (see Tables 5 & 6 and Figures 3 & 5). After the simulation, the peer leader leads a wrap-up discussion with the whole class to reinforce and summarize the transformations in each step. Using the simulation the students have just completed, the peer leader asks questions to help students identify the source of matter and energy for each step, along with the destination for both atoms and energy within the products and guides completion of summary tables for photosynthesis (Figure 4) and cellular respiration (Figure 6). Discussion questions and simulation formulas can be integrated into a PowerPoint presentation to facilitate the activity, especially for peer-led sessions.

Figure 2.
Flow chart depicting the steps in the photosynthesis and cellular respiration simulation. A peer leader should guide students through these four activities for the light reactions, the Calvin cycle, the catabolic steps of cellular respiration, and oxidative phosphorylation.
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Flow chart depicting the steps in the photosynthesis and cellular respiration simulation. A peer leader should guide students through these four activities for the light reactions, the Calvin cycle, the catabolic steps of cellular respiration, and oxidative phosphorylation.

Figure 2.
Flow chart depicting the steps in the photosynthesis and cellular respiration simulation. A peer leader should guide students through these four activities for the light reactions, the Calvin cycle, the catabolic steps of cellular respiration, and oxidative phosphorylation.
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Flow chart depicting the steps in the photosynthesis and cellular respiration simulation. A peer leader should guide students through these four activities for the light reactions, the Calvin cycle, the catabolic steps of cellular respiration, and oxidative phosphorylation.

Table 5.
A summary of the simulation procedure for photosynthesis. Equations for students and specific action instructions are included for all four steps.
Equation for chemical changes in each modeling step (present to students)Specific actions that students complete in each step
Step 1: Photosynthesis Light reactions — Matter 
12 H2O → 6 O2 + 12 H− atoms (containing 2e− each) + 12 H+ Oxidize 12 H2O to form O2 and release 12 H− and 12 H+ 
Place released O2 to the side to be released from cell 
Place released 12 H− and 12 H+ to the side 
Note: Instructor ask students to identify where the hydrogen atoms and their electrons should be transferred. The correct answer is the electron carriers. 
12 NADP+ + 12 H− (2e− each) → 12 NADPH Use 12 H− released from water to reduce NADP to produce NADPH 
Step 2: Photosynthesis Light reactions — Energy 
20 ADP + Pi → 20 ATP Add 20 ATP, transfer 10 energy stickers from package to ATP 
12 NADP+ + 12 H− (2e− each) → 12 NADPH Transfer 24 energy stickers from package to NADPH 
Note: Since the energy source is the sun, students use stickers directly from the package for this step. It is helpful to leave stickers in large groups affixed to reinforced backing to reduce time and allow for re-use in multiple sections. 
Step 3: Photosynthesis Calvin cycle — Matter 
12 NADPH → 12 NADP+ + 12 H− (2e− each) + 12 H+ Oxidize 12 NADPH to release 12 H+ and 12 H− and set to the side 
Release 24 energy stickers from NADPH and save for next step 
Note: Instructor asks students to identify where the hydrogen atoms and their electrons should be transferred. The correct answer is the G3P molecules. 
6 CO2 + 12 H− (2e− each) + 12 H+ → 2 G3P (3 C, 3 O, and 6 H each) + 6 H2O Reduce 6 CO2 with 12 H+ and 12 H− released from NADPH to generate 2 G3P 
Step 4: Photosynthesis Calvin cycle — Energy 
12 NADPH → 12 NADP+ + 12 H− (2e− each) + 12 H+ Transfer saved 24 energy stickers to 2 G3P molecules 
20 ATP → 20 ADP + Pi Transfer 10 energy stickers from ATP to 2 G3P molecules, remove ATP 
Final Step: Photosynthesis 
2 G3P → Glucose Convert 2 G3P to generate 1 glucose molecule 
Transfer 6 additional energy stickers from the package, since the source is undefined. 
Note: This glucose molecule (with 40 associated energy stickers) will serve as fuel for cellular respiration in the organism. At this point, the simulation can be suspended until the next class period. 
Equation for chemical changes in each modeling step (present to students)Specific actions that students complete in each step
Step 1: Photosynthesis Light reactions — Matter 
12 H2O → 6 O2 + 12 H− atoms (containing 2e− each) + 12 H+ Oxidize 12 H2O to form O2 and release 12 H− and 12 H+ 
Place released O2 to the side to be released from cell 
Place released 12 H− and 12 H+ to the side 
Note: Instructor ask students to identify where the hydrogen atoms and their electrons should be transferred. The correct answer is the electron carriers. 
12 NADP+ + 12 H− (2e− each) → 12 NADPH Use 12 H− released from water to reduce NADP to produce NADPH 
Step 2: Photosynthesis Light reactions — Energy 
20 ADP + Pi → 20 ATP Add 20 ATP, transfer 10 energy stickers from package to ATP 
12 NADP+ + 12 H− (2e− each) → 12 NADPH Transfer 24 energy stickers from package to NADPH 
Note: Since the energy source is the sun, students use stickers directly from the package for this step. It is helpful to leave stickers in large groups affixed to reinforced backing to reduce time and allow for re-use in multiple sections. 
Step 3: Photosynthesis Calvin cycle — Matter 
12 NADPH → 12 NADP+ + 12 H− (2e− each) + 12 H+ Oxidize 12 NADPH to release 12 H+ and 12 H− and set to the side 
Release 24 energy stickers from NADPH and save for next step 
Note: Instructor asks students to identify where the hydrogen atoms and their electrons should be transferred. The correct answer is the G3P molecules. 
6 CO2 + 12 H− (2e− each) + 12 H+ → 2 G3P (3 C, 3 O, and 6 H each) + 6 H2O Reduce 6 CO2 with 12 H+ and 12 H− released from NADPH to generate 2 G3P 
Step 4: Photosynthesis Calvin cycle — Energy 
12 NADPH → 12 NADP+ + 12 H− (2e− each) + 12 H+ Transfer saved 24 energy stickers to 2 G3P molecules 
20 ATP → 20 ADP + Pi Transfer 10 energy stickers from ATP to 2 G3P molecules, remove ATP 
Final Step: Photosynthesis 
2 G3P → Glucose Convert 2 G3P to generate 1 glucose molecule 
Transfer 6 additional energy stickers from the package, since the source is undefined. 
Note: This glucose molecule (with 40 associated energy stickers) will serve as fuel for cellular respiration in the organism. At this point, the simulation can be suspended until the next class period. 
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Table 6.
Summary of the procedure to simulate cellular respiration. Equations for students and specific action instructions are included for all four steps.
Equation for chemical changes in each modeling step (present to students)Specific actions that students complete in each step
Step 1: Cellular respiration: Glucose catabolism — Matter 
C6H12O6 + 6 H2O → 6 CO2 + 12 H− (2e− each) + 12 H+ Catabolize and oxidize glucose and water to generate 6 CO2 and 12 H− and 12 H+ 
Set released CO2 to the side for release from cell 
Set 12 H− and 12 H+ released from oxidation to the side 
Release 40 energy stickers from glucose and save for next step 
Note: Instructor should ask students to identify where the hydrogen atoms and their electrons should be transferred. The correct answer is the electron carriers. 
10 NAD+ + 10 H− (2e− each) → 10 NADH Reduce NAD+ with 10H− released from glucose oxidation 
2 FAD + 2 H− (2e− each) + 2 H+ → 2 FADH2 Reduce FAD with 2H− and 2H+ released from glucose oxidation to generate 2 FADH2 
Step 2: Cellular respiration: Glucose catabolism — Energy 
4 ADP + Pi → 4 ATP Generate 4 ATP and transfer 2 energy stickers from glucose to ATP 
10 NAD+ + 10 H− (2e− each) → 10 NADH Transfer 20 energy stickers from glucose to NADH 
2 FAD + 2 H− (2e− each) + 2 H+ → 2 FADH2 Transfer 4 energy stickers from glucose to FADH2 
Move the remaining 14 energy stickers to heat 
Step 3: Cellular respiration: Oxidative phosphorylation — Matter 
10 NADH → 10 NAD+ + 10 H− (2e− each) Oxidize 10 NADH to release 10 H− and set to the side 
2 FADH2 → 2 FAD + 2 H− (2e− each) + 2 H+ Oxidize 2 FADH2 to release 2 H− and 2 H+ and set to side 
Release 24 energy stickers from NADH and FADH2 and save for next step 
Note: Instructor should ask students to identify where the hydrogen atoms and their electrons should be transferred. The correct answer is to oxygen to form water. 
12 H− (2e− each) + 12 H+ + 6 O2 → 12 H2O Use 12 H− released from NADH and FADH2 and saved 12 H+ to reduce 6 O2 and generate 12 H2O 
Set 12 H2O to the side to be released 
Step 4: Cellular respiration: Oxidative phosphorylation — Energy 
28 ADP + Pi → 28 ATP Generate 28 ATP and transfer 14 energy stickers from NADH and FADH2 to ATP 
Move remaining 10 energy stickers to heat 
Equation for chemical changes in each modeling step (present to students)Specific actions that students complete in each step
Step 1: Cellular respiration: Glucose catabolism — Matter 
C6H12O6 + 6 H2O → 6 CO2 + 12 H− (2e− each) + 12 H+ Catabolize and oxidize glucose and water to generate 6 CO2 and 12 H− and 12 H+ 
Set released CO2 to the side for release from cell 
Set 12 H− and 12 H+ released from oxidation to the side 
Release 40 energy stickers from glucose and save for next step 
Note: Instructor should ask students to identify where the hydrogen atoms and their electrons should be transferred. The correct answer is the electron carriers. 
10 NAD+ + 10 H− (2e− each) → 10 NADH Reduce NAD+ with 10H− released from glucose oxidation 
2 FAD + 2 H− (2e− each) + 2 H+ → 2 FADH2 Reduce FAD with 2H− and 2H+ released from glucose oxidation to generate 2 FADH2 
Step 2: Cellular respiration: Glucose catabolism — Energy 
4 ADP + Pi → 4 ATP Generate 4 ATP and transfer 2 energy stickers from glucose to ATP 
10 NAD+ + 10 H− (2e− each) → 10 NADH Transfer 20 energy stickers from glucose to NADH 
2 FAD + 2 H− (2e− each) + 2 H+ → 2 FADH2 Transfer 4 energy stickers from glucose to FADH2 
Move the remaining 14 energy stickers to heat 
Step 3: Cellular respiration: Oxidative phosphorylation — Matter 
10 NADH → 10 NAD+ + 10 H− (2e− each) Oxidize 10 NADH to release 10 H− and set to the side 
2 FADH2 → 2 FAD + 2 H− (2e− each) + 2 H+ Oxidize 2 FADH2 to release 2 H− and 2 H+ and set to side 
Release 24 energy stickers from NADH and FADH2 and save for next step 
Note: Instructor should ask students to identify where the hydrogen atoms and their electrons should be transferred. The correct answer is to oxygen to form water. 
12 H− (2e− each) + 12 H+ + 6 O2 → 12 H2O Use 12 H− released from NADH and FADH2 and saved 12 H+ to reduce 6 O2 and generate 12 H2O 
Set 12 H2O to the side to be released 
Step 4: Cellular respiration: Oxidative phosphorylation — Energy 
28 ADP + Pi → 28 ATP Generate 28 ATP and transfer 14 energy stickers from NADH and FADH2 to ATP 
Move remaining 10 energy stickers to heat 
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Figure 3.
Visual summary of the simulation procedure for photosynthesis. Students will manipulate game pieces and energy stickers to depict transformation of matter and energy in each step. The written equations and instructions under each image can be provided to the students during the stimulation.
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Visual summary of the simulation procedure for photosynthesis. Students will manipulate game pieces and energy stickers to depict transformation of matter and energy in each step. The written equations and instructions under each image can be provided to the students during the stimulation.

Figure 3.
Visual summary of the simulation procedure for photosynthesis. Students will manipulate game pieces and energy stickers to depict transformation of matter and energy in each step. The written equations and instructions under each image can be provided to the students during the stimulation.
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Visual summary of the simulation procedure for photosynthesis. Students will manipulate game pieces and energy stickers to depict transformation of matter and energy in each step. The written equations and instructions under each image can be provided to the students during the stimulation.

Figure 4.
Summary table for photosynthesis. Students complete the table using observations from the simulation and during class discussion. For a printable version of this figure, please send an email request to lacesvec@georgiasouthern.edu
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Summary table for photosynthesis. Students complete the table using observations from the simulation and during class discussion. For a printable version of this figure, please send an email request to lacesvec@georgiasouthern.edu

Figure 4.
Summary table for photosynthesis. Students complete the table using observations from the simulation and during class discussion. For a printable version of this figure, please send an email request to lacesvec@georgiasouthern.edu
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Summary table for photosynthesis. Students complete the table using observations from the simulation and during class discussion. For a printable version of this figure, please send an email request to lacesvec@georgiasouthern.edu

Figure 5.
Visual summary of the simulation procedure for cellular respiration. Students will manipulate game pieces and energy stickers to depict transformation of matter and energy in each step. The written equations and instructions under each image can be provided to the students during the stimulation.
View largeDownload slide

Visual summary of the simulation procedure for cellular respiration. Students will manipulate game pieces and energy stickers to depict transformation of matter and energy in each step. The written equations and instructions under each image can be provided to the students during the stimulation.

Figure 5.
Visual summary of the simulation procedure for cellular respiration. Students will manipulate game pieces and energy stickers to depict transformation of matter and energy in each step. The written equations and instructions under each image can be provided to the students during the stimulation.
View largeDownload slide

Visual summary of the simulation procedure for cellular respiration. Students will manipulate game pieces and energy stickers to depict transformation of matter and energy in each step. The written equations and instructions under each image can be provided to the students during the stimulation.

Figure 6.
Summary table for cellular respiration. Students complete the table using observations from the simulation and during class discussion. For a printable version of this figure, please send an email request to lacesvec@georgiasouthern.edu
View largeDownload slide

Summary table for cellular respiration. Students complete the table using observations from the simulation and during class discussion. For a printable version of this figure, please send an email request to lacesvec@georgiasouthern.edu

Figure 6.
Summary table for cellular respiration. Students complete the table using observations from the simulation and during class discussion. For a printable version of this figure, please send an email request to lacesvec@georgiasouthern.edu
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Summary table for cellular respiration. Students complete the table using observations from the simulation and during class discussion. For a printable version of this figure, please send an email request to lacesvec@georgiasouthern.edu

To model photosynthesis, students utilize sun energy stickers to anabolize sugars with high potential energy, eventually generating a glucose molecule (see instructions and images in Table 5 and Figure 3). The simulation takes place in four parts: matter and energy transformation in the light reactions (Steps 1 and 2), and matter and energy transformation in the Calvin cycle (Steps 3 and 4). If time is limited, it is easy to stop the simulation after completing photosynthesis and continue with cellular respiration in another class period.

Next, students simulate cellular respiration (see instructions and images in Table 6 and Figure 5) by catabolizing and oxidizing glucose to form water and carbon dioxide, releasing energy stickers that are used to generate ATP. Cellular respiration is simulated in four steps: matter and energy transformation in glucose catabolism (Steps 1 and 2), and matter and energy transformation in oxidative phosphorylation (Steps 3 and 4). At the completion of all steps, instructors guide students through completion of the summary tables (Figures 4 and 6); a completed summary table for photosynthesis (Figure 7) is included for reference.

Figure 7.
Example completed summary table for photosynthesis.
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Example completed summary table for photosynthesis.

Figure 7.
Example completed summary table for photosynthesis.
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Example completed summary table for photosynthesis.

Conclusion

To visually consolidate information at the end of the simulation, instructors can ask students to generate flow charts depicting the movement of carbon, electrons, or energy on the cellular, organismal (autotroph or heterotroph), or ecosystem level through photosynthesis and cellular respiration. The flow charts reinforce the concepts of matter cycling and energy flow and provide an opportunity for the instructor to informally assess student knowledge and understanding of the processes of cellular respiration and photosynthesis. Other possible assessment methods are outlined in Table 7. In small or large classrooms, instructors could also utilize application questions to ensure students can (a) identify the source of food or energy in different organisms, (b) identify the transformation of matter during weight loss or gain, and/or (c) apply these concepts to scenarios such as Joseph Priestley's Bell jar experiments.

Table 7.
Potential formal and informal assessments of student learning following completion of in-class photosynthesis and cellular respiration simulation activity.
Potential assessment:Example:
Draw a figure Draw the path of BOTH matter and energy through the processes of cellular respiration and photosynthesis. 
Generate a table Complete summary tables with information gathered during the simulation, as shown in Figures 5 and 7. 
Describe the path Describe the path of a single electron or one carbon atom through cellular respiration and/or photosynthesis. 
Apply to experimental results Explain the results from Joseph Priestley's experiment in which a mouse died after being placed in an enclosed jar, but survived when a plant was added to the jar. 
Edit inaccurate statements Edit the following example statements: (1) A plant is kept in the dark for three days, but watered normally. The plant loses dry weight because it cannot conduct photosynthesis. (2) Sunny lost 100 lbs over four weeks, and all her lost weight was converted into ATP. 
Multiple choice questions: principles of conservation of matter and energy What is the source of energy for building sugars in the Calvin cycle? Where are electrons released from electron carriers transferred in oxidative phosphorylation? Other sample questions can be found in Wilson et al. 2006, Parker et al. 2011, and Hartley et al. 2011. 
Multiple choice questions: application of concepts to real world situations Multiple-choice or essay questions in which students are required to apply the simulation to real world situations. For example: A tree increases in mass over the summer; what is the primary source of dry mass for the growth of this tree? More sample questions can be found in Wilson et al. 2006, Parker et al. 2011, and Hartley et al. 2011. 
Potential assessment:Example:
Draw a figure Draw the path of BOTH matter and energy through the processes of cellular respiration and photosynthesis. 
Generate a table Complete summary tables with information gathered during the simulation, as shown in Figures 5 and 7. 
Describe the path Describe the path of a single electron or one carbon atom through cellular respiration and/or photosynthesis. 
Apply to experimental results Explain the results from Joseph Priestley's experiment in which a mouse died after being placed in an enclosed jar, but survived when a plant was added to the jar. 
Edit inaccurate statements Edit the following example statements: (1) A plant is kept in the dark for three days, but watered normally. The plant loses dry weight because it cannot conduct photosynthesis. (2) Sunny lost 100 lbs over four weeks, and all her lost weight was converted into ATP. 
Multiple choice questions: principles of conservation of matter and energy What is the source of energy for building sugars in the Calvin cycle? Where are electrons released from electron carriers transferred in oxidative phosphorylation? Other sample questions can be found in Wilson et al. 2006, Parker et al. 2011, and Hartley et al. 2011. 
Multiple choice questions: application of concepts to real world situations Multiple-choice or essay questions in which students are required to apply the simulation to real world situations. For example: A tree increases in mass over the summer; what is the primary source of dry mass for the growth of this tree? More sample questions can be found in Wilson et al. 2006, Parker et al. 2011, and Hartley et al. 2011. 
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I thank fellow instructor, Loren Mathews, supplementary instruction peer leaders, and former students for help in refinement of this activity, and Risa Cohen and two anonymous reviewers for editorial and content advice.

References

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2017