Name: _________________
Date: _________________
Period: ______
Cellular Respiration Activity
Problem: How does exercise affect disposal of waste (CO2) from cellular respiration.
Materials:
6 flasks
50 ml beaker
5 ml bromothymol blue per student
10 ml, 100 ml graduated cylinders
6 straws
clock or stopwatch
Procedure: Directions: Circle any measurements you need to make.
1. You will complete this lab in a group of four: two people are the recorders and the other two will perform
the exercise.
2. Record your hypothesis above, as to how exercise will affect your body’s production of CO2
3. Label 6 flasks A-F. Put 50 ml of water and 5 ml of bromothymol blue in each flask.
Bromothymol blue (BTB) is an indicator of pH. When CO2 is bubbled through water, carbonic acid is
formed. CO2 + H2O  H2CO3. BTB changes color toward yellow in the presence of an acid. The
more yellow the BTB is, the more carbon dioxide is present.
4. When the recorders say ‘go’, the performers should gently blow air through the straw into the bottom of
flasks A (person 1) and B (person 2). CAUTION: Do not inhale through the straw!
5. The recorders will record the time it takes for the color to change from ________ to ________.
6. Now the performers should jog in place for 1 minute and repeat steps 3 and 4 using flasks C and D.
CAUTION: If you feel dizzy or weak while exercising, stop immediately and sit down.
7. Finally – the performers should sprint or run for 1 minute and repeat steps 3 and 4 using flasks E and F.
Pre-Lab Questions:
a. Independent Variable: ___________________________ (x-axis)
b. Dependent Variable: ____________________________ (y-axis)
c. Control Group:_______________________________________
i. Why do you need this control group:
______________________________________________________________________
__________________________________________________________
d. Constants: ____________________
_________________
___________________
e. What SAFETY precautions do you need to take in this lab?
f.
g. Hypothesis:
If someone exercises, then ________________________________________________.
h. Rationale (explain the why)_________________________________________________
______________________________________________________________________
Data Collection:
Person #1 Results
Time for solution to
change color(sec)
Before exercise
After Light exercise
After Intense exercise
Person #2 Results
Time for solution to
change color(sec)
Before exercise
After Light exercise
After Intense exercise
Your group’s average time before exercise: __________________
Your group’s average time after light exercise: __________________
Your group’s average time after intense exercise: __________________
Average time before exercise of three other groups: 1. __________ 2.__________ 3.__________
Average time after light exercise of three other groups: 1. __________ 2.__________ 3.__________
Average time after intense exercise of three other groups: 1. __________ 2.________ 3.__________
Data Analysis:
2. On the attached graph paper, plot the average time before and after exercise of your group as
compared to three other groups’ average times. This is a BAR GRAPH, and you should plot 12
different bars (1 Ave before exercise, and 2 Averages after exercise). Remember to label your X-, Yaxis, and include a title for your graph.
3. What process in your body produces carbon dioxide?
4. How does exercise affect this process? How do you know? Cite your data.
5. Was there a difference between the two experimental groups? Explain why or why not, citing your data.
Conclusion:
1. Address your hypothesis:
How did exercise affect the time for the BTB solution to change color?
Did these results support/reject your hypothesis?
2. How were you able to determine the amount of CO2 that was produced? Describe the process.
3. Why is cellular respiration important to your body?
4. What would happen if your cells were not getting enough oxygen during the running portion of the lab?
Explain in 2-3 full sentences. What are the products of this reaction?
5. Error analysis: What do you think are potential sources of error? List at least 3.
_____________________________________________________________