LAB Exercise and Cellular Respiration hf7DFQx PDF

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Exercise and Cellular Respiration Lab Purpose Question: How will exercise affect your cellular respiration rate? Objectives by end of lab: I can… • Describe the overall effect of exercise on cellular respiration. • Describe the effect of exercise on carbon dioxide production. • Describe how I illustrated the effects of exercise on CO2 production during this lab. Background: 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. Glucose is a common fuel for the process of cellular respiration. The complex sugar, starch, is broken down into a simple sugar, glucose, by the digestive system. Humans and many other animals store another form of starch called glycogen in the liver and muscle cells. Glycogen can also be changed into glucose and used to fuel cellular respiration. Glucose is not the only fuel the body can use. For example, proteins and fats can also be used. Proteins are broken down into their monomer amino acids and then modified to be used in the Kreb’s cycle with the help of enzymes. Fats, whether taken in with food or stored in the body, provide excellent fuel for respiration. A gram of fat produces more than double the amount of ATP than a gram of carbohydrate does. Although in the lab we cannot physically see this breakdown, we will examine how exercise and physical exertion affects cellular respiration. If we were to increase our activity level, we should expect an increase in the amount of carbon dioxide we exhale. This 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! Prelab Questions: 1. Why does carbon dioxide increase during exercise? ________________________________________________________________________________ ________________________________________________________________________________ 2. How do we generate energy (ATP) for longer periods of exercise? ________________________________________________________________________________ ________________________________________________________________________________

3. How are we observing the presence of carbon dioxide in this lab? ________________________________________________________________________________ ________________________________________________________________________________ Introduction: In this lab, you will determine how exercise affects cellular respiration. Cellular Respiration is the process that releases energy by breaking down food molecules in the presence of oxygen. The following chemical equation summarizes cellular respiration:

enzymes CH2O

+

carbohydrates

O2 oxygen

+



CO2

+

carbon dioxide

H2 O water

+

36 ATP energy

In this lab we will be using an indicator called bromothymol blue to test for the presence of carbon dioxide. Bromothymol blue (usually blue in color) turns green/yellow in the presence of carbon dioxide.

Lab Roles    

Leader: Gives instructions to group. Only the leader reader may ask the teacher questions. Time Keeper: Gets the lab materials, keeps time for the joggers. Jogger #1: Tested for CO2 at rest and after jogging for 2 mins. Jogger #2: Tested for CO2 at rest and after jogging for 2 mins.

Materials   

2 small clear cups Pen of Pencil 10 mL graduated cylinder

  

Bromothymol blue solution (2 drops) 2 straws Time keeping device

Define the Variables 

Independent



Dependent



Control



Constants

State Your Hypothesis ________________________________________________________________________________ ________________________________________________________________________________ ________________________________________________________________________________

Procedure: We will be using bromothymol blue (BTB) solution as an indicator of CO2. Health Concern: Do NOT ingest BTB! 1. Preparing the solution - Put 50 mL of water and a dropper full of BTB in each flask. Cover the flask with parafilm. Then stick a straw through the parafilm. 2. While a partner times you, slowly blow air through a straw into the bottom of the flask until the solution turns yellow/green (when carbon dioxide combines with the BTB it changes the color from BLUE to YELLOW/GREEN). Do not let the solution get in your mouth! 3. Record the time it takes for the color change to occur. 4. Dump out the BTB solution, rinse with tap water, and create another 50mL of BTB solution. 5. Have the same person who blew through the straw in step 2 run up and down the stairs for 1 minute. 6. After the time is up, have the runner blow through the straw again until the BTB solution changes to the yellow-green color. 7. Record the time it takes for the color change to occur. 8. Dump out the BTB solution, rinse with tap water, and create another 50mL of BTB solution. 9. Have the same runner run up and down the stairs for 2 minutes. 10. After the time is up, have the runner blow through the straw again until the BTB solution changes to the yellow-green color. 11. Record the time it takes for the color change to occur. 12. Dump out the BTB solution, rinse with tap water, and create another 50mL of BTB solution. Repeat the experiment with another group member.

Data and Observations Time Elapsed Before Color Change- Jogger #1

Time Elapsed Before Color Change- Jogger #2

Before Exercise (control) After 1 minute After 2 minutes

Analysis Create a line graph of your data and your lab partner’s data. Answer the questions that follow. 1.

From your graph, what trends do you see? Which of your trials was longest to change the BTB? Why? Which of your trials was shortest to change the BTB? Why? ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________

2.

From your graph, how does your data compare to your lab partners? (Was there a difference and how can you explain the difference?) ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ 3. Which group member had the most efficient cellular respiration? Explain your answer. ________________________________________________________________________ ________________________________________________________________________

Conclusion 1. What gas was present in your breath to change the BTB?

2. What process in your body produces carbon dioxide?

3. How did exercise affect the time for the solution to change color?

4. Was your hypothesis supported or rejected? How do you know?

5. What are some possible sources of error in this experiment?

6. How do you think the results would have changed if the joggers had held their breath while jogging in place? (Consider the graph below)....