Your Name:

People in Lab Group Names:

Exercise and Cellular Respiration Lab Screen Shot 2015-11-16 at 1.44.11 PM.png

What happens when you exercise? As you know, increasing your activity level will cause an increase in your respiration rate. What you may not know is that this is closely tied to cellular respiration in your cells. As you increase your activity, mitochondria in your cells use oxygen to break down sugars to charge up ATP molecules; ATP is then used for energy directly elsewhere in your cells, including muscle work. A waste product of the breakdown of sugars is carbon dioxide gas, which you exhale.

For quick energy, the body uses already-stored ATP and new ATP made by lactic acid fermentation. These sources can only supply enough ATP to last about 90 seconds!

For exercise longer than 90 seconds, cellular respiration is the only way to generate a continuing supply of ATP. Cellular respiration releases energy more slowly than fermentation, which is why you have to pace yourself during long sessions of exercise.

In this lab we will examine how exercise affects cellular respiration.  The carbon dioxide we exhale can be measured by a blue solution of BTB (bromothymol blue). This chemical turns yellow-green in the presence of carbonic acid, the chemical resulting when carbon dioxide gas mixes with water. All you need to do is blow through a straw into a solution of BTB to detect it!

Part A: Pre-Lab Questions:

1. How do we generate energy (ATP) for longer periods of exercise? 

2. How are we observing the presence of carbon dioxide in this lab?

Part B: Investigation


How will exercise affect your cellular respiration rate?  



Independent Variable (IV): The variable you manipulated or changed

Dependent Variable (DV):  The variable that will respond to the independent variable (what you measure).

DV units: How will the dependent variable be measured

Control Test: What the IV is compared to in order to know the change was due to your test, and not some random variable.

Constant Variables: What you try to keep the same

Part C:  Designing the Investigation

Materials List:

  • Bromothymol blue indicator solution  

  • 2 straws
  • timer


We will be using bromothymol blue (BTB) solution as an indicator of CO2. As BTB comes in contact with CO2, the blue solution will turn yellow-green. Do NOT ingest BTB!

  1. Preparing the solution - Put 50 mL of water and a 12 drops of BTB in each beaker.

  1. Using a stopwatch, while a partner times you, slowly blow air through a straw into the bottom of the flask until the solution turns yellow/green.   Do not let the solution get in your mouth!

  1. Record the time it takes for the color change to occur.

  1. Dump out the BTB solution into the sink, rinse the beaker with tap water, and create another 50 mL of BTB solution.

  1. Have the same person who blew through the straw in step 2 do jumping jacks for 1 minute.

  1. After the time is up, have the jumper blow through the straw again until the BTB solution changes to the yellow-green color; see your teacher to reset your solution and return it to the blue color.

  1. Record the time.

  1. Repeat the procedures again, with jumper at 1:30 minutes and 2 minutes.

  1. Repeat the experiment with another group member.

Part D:  Collecting Data

Data Table 1: How exercise affects carbon dioxide production

Time Elapsed Before Color Change

Amount of exercise

Student 1

Student 2

Student 3 (if you have three)


No exercise

1 min burpees

1:30 min jumping jacks

2 min jumping jacks

Create a graph of your data and your lab partner’s data.  


Part F: Post-Lab Questions

  1. From your graph, which of your trials was longest to change the BTB? Why?


  1. From your graph, which of your trials was shortest to change the BTB? Why?

  1. From your graph, How does your data compare to your lab partners? (Was there a difference?)

  1. Which group member had the most efficient cellular respiration? Explain your answer.

  1. What process in your body produces carbon dioxide? How did exercise affect this process?

Assessment Practice

Exceeds (4)

Meets (3)

Nearly Meets (2)


Hypothesis & Variables:

❑  Hypothesis or question  clearly articulates expectations of the experiment

❑  Several appropriate constants listed &  controlled.

Procedure & Background:

❑  Procedure allows for the control of variables & constants

❑  Background connects lab to larger ideas or previous topics


❑  Suggests improvements to limitations, errors, or weaknesses of experiment

❑  Applies related concepts to topics in the news, scientific community, or your life.

❑  At least one credible, external, citation used (MLA format)  furthers relates the lab to bigger ideas and topics

Hypothesis & Variables:

❑  States testable question and hypothesis

❑  Lists IV, DV & Control and at least two appropriate constant

Procedure & Background:

❑    Procedure is repeatable and has clear and numbered steps

❑  Background describes purpose of the lab


❑  States an explanation, with justification, based on analysis of the data.

Includes at least one ‘data statement’ to support the explanation.

❑  Links findings to original question or hypothesis

Hypothesis & Variables:

⠂ Hypothesis unclear
⠂Incorrectly identifies IV, DV, Control, or does not state at least two  appropriate constants

Procedure & Background:

⠂Procedure that is not  repeatable and/or clear

⠂Background unclear


⠂States an explanation that does not include justification using data

⠂Limited connection of findings to original question or hypothesis

Hypothesis & Variables:

⠂ Does not state a  testable question and/or  hypothesis

⠂Does not include an  IV, DV and/or Control and states less than 2 appropriate constants

Procedure & Background:

⠂Procedure missing many steps or measurements

⠂No background missing or has no connection to lab


⠂States no explanation or justification

⠂Data statement not present

⠂No connection of findings to original question

Data Analysis:

❑   Calculations are used when appropriate (mode, average, error or uncertainties)

❑   Raw data table includes title, units and calculations

Data Analysis:

❑   Raw data table includes title, units and raw data

❑   Type of graph clearly illustrates data trends for analyzed data and includes units

❑   Labeling of graph is correct (axis, units, and title)

Data Analysis:

⠂Data table is missing appropriate title, units or raw data

⠂Type of graph is not appropriate for analyzed data

⠂Labeling of graph is not correct (axis, units, and title)

Data Analysis:

⠂Data table is illegible or not present

⠂Graph is not present

⠂Labeling of graph is missing