Name _________________________ Date _______________ Block __________
The Effects of Exercise on Cellular Respiration
Bromothymol blue is a chemical indicator that changes color as the pH of a solution changes. It is yellow
in acidic solutions and blue in basic and neutral solutions. When carbon dioxide is dissolved in water, it
creates carbonic acid, pH~5.7. This reaction occurs as rainwater absorbs carbon dioxide. When else
might you see examples of this occurrence?
One of the products of Cellular Respiration is carbon dioxide. As cells produce CO
respiration, it is carried by our blood cells to our lungs where it is exhaled. You can measure the rate your
cells carry out cellular respiration by measuring how quickly you produce carbon dioxide. You will first
determine your resting rate of cellular respiration, and then you will determine your rate after exercise.
1. How is breathing related to cellular respiration? ________________________________________
2. Hypothesize: How will exercise affect the rate of cellular respiration?
3. How can Bromothymol blue pH help you measure your rate of cellular respiration?
4. Your partner will stop the time as soon as the
• drinking straw
5. Record the time it took for the color change
• bromothymol blue solution
in the observation table below. This is the
• 2-250 mL beakers
• graduated cylinder
6. Rinse out the beaker, and refill with 40 mL
• SAFETY GOGGLES
water and 10 mL bromothymol blue solution.
7. Now have the experimenter do jumping jacks
or a similar exercise for 1 minute. You
1. Fill the beaker with 40 mL water and 10 mL
should feel a little winded when you are
bromothymol blue solution.
2. Assign one person to be the timer, and one
8. Using the same straw, exhale into the
person to perform the experiment.
solution the same way as in the control group
3. When the timer says “START”, the
and record how long it takes for the solution
experimenter will exhale through the straw
to change color.
into the bromothymol blue solution until the
9. Write down the time it took for the color
color changes from blue to green.
change in the observation table below.
Do NOT inhale the solution!
Exhale from your lungs!