Objective: to Predict What Will Happen to the Rate of Cellular Respiration As a Result

Respiration Lab

Background Information: Each time you take a breath, an exchange of gases occurs between you and the atmosphere. You take in oxygen-rich air and push out carbon dioxide gas. Oxygen molecules are used to break down food and provide energy for everything you do. One of the products of this process is carbon dioxide. In this activity, you will explore how physical activity affects carbon dioxide production.

In this lab you will be using bromothymol blue, which is a carbon dioxide indicator that will change color from blue to green/yellow in the presence of carbon dioxide. CAUTION: Bromothymol blue can stain your clothes.

Objective: To predict what will happen to the rate of cellular respiration as a result of exercise.

Hypothesis: Write a statement that explains what will happen to your rate of respiration after exercising and how that will affect the amount of time it takes to change the color of the indicator. If we use bromothymol blue to check the rate of respiration after exercising, then the time that it takes for the indicator to change color will be… (shorter, longer, cut in half, ____ seconds, etc.)

Materials: stopwatch test tubes straws bromothymol blue test tube rack graduated cylinder paper towels

Procedure: 1) Measure 5 ml of bromothymol blue solution and pour it into a test tube, repeat for the second test tube. 2) Record the length of time that it takes to change the color of the indicator from blue to yellow. Slowly blow into the test tube. SAFETY: Use a paper towel to cover the opening so you do not splash the solution into your mouth. 3) Continue blowing into the tube until the solution changes color. Record the time in the chart under “resting time.” 4) Exercise for three minutes and repeat steps 2 and 3, recording the data in the chart under “time after exercise.” 5) Have student #2 repeat steps 1-4 and record the data in the chart.

Results: TITLE: Data Table Time at Rest Time After Exercise Name of Student (seconds) (seconds) You (Name) Partner (Name)

Analysis: 1) Initially, what color was the indicator? What color was the indicated after you exhaled into it? 2) How did exercise affect the time it took the indicator to change color? How did your results compare to your partner’s? 3) How does exercise affect cellular respiration? How do you know? 4) What other factors could affect your rate of respiration? 5) Can you improve your rate of respiration? If so how?