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.