Name:____________________________________ Date: _____________Block:_______
How does exercise affect cellular respiration?
We just learned about respiration and how it occurs. When oxygen is present the type of
respiration used is aerobic respiration. When oxygen is not present the type of respiration used
is anaerobic respiration.
PART A: AEROBIC RESPIRATION
We know when aerobic respiration occurs some carbon from glucose is given off as CO2 into the
atmosphere. The purpose of this lab is to literally “see” the CO2 given off from the process and to
see how exercise affects the speed at which Co2 is produced. To measure CO2 production, you will
use Bromothymol blue. Bromothymol blue is an indicator for CO2; when CO2 is present
Bromothymol blue will turn yellow or green. Record your hypothesis below of how exercise will
affect your body’s production of CO2. Will exercise produce more or less CO2 than when you are
at rest?
Hypothesis:
Materials:
2 test tubes (for each person)
10mL graduated cylinder
Bromthymol blue solution
2 Straws (one for each person)
Watch, clock, or stopwatch
Safety glasses
Procedure
1. Put 5mL of water and 4 drops of Bromothymol blue solution in a test tube. Your partner will
time you during this step. When your partner says “go,” slowly blow air through a straw into
the bottom of test tube A. CAUTION- Do not inhale through the straw!
2. When the solution changes color, your partner should say “stop,” and then record how long
the color change took. Record this time as trial 1 for test tube A in Table 1.
3. Repeat step 1 two more times for your second and third trials of “at rest”.
4. Set up another test tube with 5ml of water and 4 drops of Bromothymol blue. Run up and
down the steps outside the classroom 2 times (or alternate exercise). Immediately blow
through straw into test tube B. Do not blow hard or you will splash yourself! Try to blow
the same amount of air through the straw as you did earlier. Record this time as trial 1 for
tube B in Table 1.
5. Repeat step 4 two more times for your second and third trials of “after exercise”.
6. Trade roles with your partner and have your partner test him or herself.
7. Calculate the average time for the “at rest” times and the after exercise times.
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You are only recording your data in this chart… not your partner’s!
Table 1: Individual Data for Carbon Dioxide production
Trials
Tube A
(at rest)
Tube B
(after exercise)
Time (sec) Trial 1
Time (sec) Trial 2
Time (sec) Trial 3
Average Time (sec)
PART B: ANAEROBIC RESPIRATION
Because O2 is not present during anaerobic respiration CO2 is not produced, therefore we cannot
test for CO2 since there is none present.  However, we can still technically and literally feel the
effects of anaerobic respiration during exercise. In humans, anaerobic respiration produces
lactic acid which is the burn you usually feel in your muscles after a strenuous activity.
Here’s Your Challenge:

See how long you can perform a “wall sit”, while your partner
times you. Can you beat the top times Mrs. Flick already has on
the wall? ***Remember no cheating, you cannot use your hands
at all and your back must be parallel with the wall.

Or just do the “wall sit” until you feel the burn. Make sure your
partner times how long it takes you to feel the burn.

If you don’t want to do a wall sit try this activity on for size. Hold out your arm and
lock your elbow with your palm facing up. Have your partner place two Biology text books
on your arm. See how long you can keep the books up before your arm gets tired. Make
sure your partner is timing you!
Repeat one of the above activities 2 times and record your data in Table 2. You should rest for
approximately 30 seconds between trials.
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Table 2: Anaerobic Exercises
Trials
Time (minutes or seconds)
Trial 1
Trial 2
Trial 3
PART A: AEROBIC RESPIRATION QUESTIONS
1. How did exercise time affect the time for the solution to change color? (Hint: Which tube
changed color faster and why?)
2. What process in your body produces CO2? How does exercise affect this process?
3. Was your hypothesis correct? Explain your answer
4. Does exercise affect the amount of glucose used? If so, how and why?
5. Does exercise affect the amount of oxygen needed? If so, how and why?
6. Explain why your rate of breathing increased after running up and down the steps. Be sure to
include oxygen, carbon dioxide, and energy in your answer.
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PART B: ANAEROBIC RESPIRATION QUESTIONS
1) What are two differences between aerobic and anaerobic respiration?
2) What was making you “feel the burn” in your muscles?
3) Were other parts of your body still going through aerobic respiration while your muscles were
going through anaerobic respiration? Hint: Was your entire body “feeling the burn” during the
activity?
4) Was your second and third trial consistent with your first trial? Why or why not?
5) What could you change in the procedure to increase your consistency in time between the
trials?
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