Cellular Respiration Activity
Purpose: To discover how exercise affects the rate of cellular respiration by quantifying the rate of
disposal of waste CO2 . To discover whether gender has an effect on cellular respiration rates.
Hypothesis: I predict that exercise will _____________________________________________
____________________________________________________________________________
I predict that girls/boys will have a higher rate of cellular respiration.
(circle one)
Materials:
2 small test tubes
10 mL graduated cylinder
test tube rack
bromothymol blue
2 straws
clock or stopwatch
Procedure:
1. Record your hypothesis, as to how exercise will affect your body’s production of CO2 .
2. Label two test tubes A and B. Put 7 mL of water and 2-3 drops of bromothymol blue in each test
tube. (Note: Bromothymol blue will turn from blue to yellow or green in the presence of
carbon dioxide.)
3. When your partner says “go,” gently blow air through the straw into the bottom of test tube A.
CAUTION: Do not inhale through the straw!
4. Your partner will record the time it takes for the color to change.
5. Next engage in physical activity such as the stairs for 3 minutes. Then repeat steps 3 and 4 using
test tube B.
6. Record your results in the chart below and on the board.
Data Collection:
Gender M or F(circle)
Your time for solution
to change color (sec)
Class Average Time for
Girls (sec)
Class Average Time for
Boys (sec)
Before Exercise
After exercise
Data Analysis: Answer the following questions on a lined piece of paper.
1. What process breaks down food to produce ATP, releasing CO2 as a waste product? Write out
the word equation and chemical equation for this process.
2. What stage(aerobic or anaerobic) of cellular respiration produces carbon dioxide?
3. How does exercise affect the rate of CO2 production?
4. What can you conclude about the effect of exercise on the rate of cellular respiration?
Explain why this effect would be necessary.
5. What happens to the carbon dioxide you produce?
6. Does exercise affect cellular respiration in boys and girls differently?
7. Make some analysis of where errors could have occurred in this lab. Make suggestions of
improvements for future labs.