Investigating the Effect of Increasing Exercise in Aerobic Respiration
Sercan Durmuş 10/A 71
Investigating the Effect of Increasing Exercise in Aerobic Respiration
How does increasing exercise affect the amount of CO2 produced by the reaction of human cells in aerobic respiration by keeping the solutions in the flasks and the time for blowing the air into the flasks same for all the trials and using the same person for the whole experiment?
If the time period of an exercise is increased, the enzymes present in human cells will work more to produce more energy needed to complete the exercise. Therefore, the amount of CO2 produced by human cells will increase as a byproduct from the aerobic respiration.
Independent: different time periods for the exercise (resting, 1 minute and 2 minutes of exercise) calculated by a stopwatch.
Dependent: the amount of CO2 released as a byproduct of aerobic respiration that is measured by adding NaOH solution to the solution in the flask
Controlled: the person, the solution for each flask, the time period for blowing air into the flasks for each trial, temperatures of solutions, atmosphere, room temperature, the place that is used for doing exercise
Note: To convert the NaOH added value to CO2 produced, the value from NaOH should be multiplied by 10. For example, for the Flask #1; 64 ml x 10 = 640 μmol, for Flask #2; 68 ml x 10 = 680 μmol …
Table 1: The results for the effect of 2 minutes of exercise on CO2 production
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Table 2: The results for the effect of 1 minute of exercise on CO2 production
Table 3: Average values for different conditions
The calculations for the new uncertainty value:
The formula for calculating the average uncertainty is
“1/ (sqrt (the number of terms))*uncertainty” (Formula)
1/ (sqrt (5))*10
After 1 minute of exercise:
1/ (sqrt (2))*10
After 2 minutes of exercise:
1/ (sqrt (3))*10
Before the air was blown into each flask after the exercise, each flask’s top was closed completely so that the solution was not affected from the air in the atmosphere. After the exercise, the air from one’s lungs was blown into the flask and the color of the solution in the flask was turned from pink to transparent because CO2 is acidic and the solution in the flask is alkaline. They neutralize themselves and a transparent solution occurs. In the experiment, three different kinds of flasks were prepared for three different conditions, resting, one minute and two minutes of exercising. The result shows that the amount of CO2 released is increased with the increase of the period of exercise.
The result supports the hypothesis, which states that as the time period of an exercise is increased, the metabolism reaction rate of human cells will increase; therefore it will result in a higher carbon dioxide concentration in our lungs. Oxygen and carbon dioxide are both present in the air. Oxygen comprises 20.9 % of the air one breathes, whereas carbon dioxide makes up only 0.03 %. (Live Strong) Those metabolic gases are transferred between the atmosphere and one’s lungs. The chemical equation for the aerobic respiration is shown below:
C6H12O6 + 6O2 → 6H2O + 6CO2 + Energy
Glucose + Oxygen → Water + Carbon Dioxide + Energy
The biggest amount of CO2 produced was observed after two minutes of exercise. The rate of aerobic respiration was faster after doing two minutes of exercise than the others, because the body requires more energy to be able to do more activity. Thus, one’s body burns more sugar and that produces more CO2 as a byproduct. The total amount of CO2 produced after two minutes of exercise is 823 μmol (See Table 3) and that is a higher value than the CO2 amount produced while resting and after one minute of exercise. The amount of CO2 produced after one minute of exercise is 735 μmol (See Table 3) and that is less than the CO2 produced after two minutes of exercise. Although the period of exercise was doubled, the amount of CO2 produced was not doubled and it increased a little. The possible reasons will be analyzed later. On the other hand, while resting, a person does not need as much energy as they need while doing exercise. As a reason for that, the amount of CO2 released is the least with 608 μmol (See Table 3).
The result of this experiment is fairly valid according to the common results from internet. The amount of CO2 produced increases with the increasing exercise (Answers). Therefore, the result of this experiment can be reliable. However, there are some sources of errors in the experiment. First of all, the method for measuring the amount of CO2 produced is unreliable. After doing the exercise, it is really hard for one to blow air into the flask from their lungs. The time passes from one blow to another may differ and that makes a huge change. Also comparing the colors of the solution are unreliable, too and that is a huge source for the human random errors. To prevent this error, carbon dioxide or pH probe can be used. Graph1 shows that three trials were taken and the results differ from each other and the error bars are long. Another source of error is taking these trials over and over without or a short break. That makes the “resting” values different. For example, after the first trial for one minute of exercise, the person who made the first activity becomes tried and his/her body burns more glucose than normal. That is another source for random errors. That is why all of the resting values are different whereas they should be closer. In addition, the CO2 produced after the activity comes not only from aerobic respiration, but also from lactic acid fermentation. Lactic acid decreases the pH of the medium, so to maintain a healthy pH; sodium bicarbonate in one’s blood buffers most lactic acid by breaking it down to water and carbon dioxide. This process results in additional carbon dioxide that must be released (Live Strong). Thus, the measured CO2 may not only be from aerobic respiration, but also anaerobic respiration. Also the cylinders used in the experiment had high uncertainty values (See Table1 and Table2) and this is a source for systematic errors. This high uncertainty value can be reduced by using more precise cylinders with an uncertainty value like ±0.1 ml. In addition, there are some limitations in this experiment. One of the limitations is that there were only 3 flasks which serve for only one trial, so after each trial these flasks had to be washed and dried for other trials. Another limitation was the amount of solution which was used to fill the flasks. That solution was run out for one time and the experiment had to be stopped. The last limitation was that provided time to finish the experiment was not enough, thus only two trials for the one minute of exercise and three trials for the two minutes of exercises could be taken (See Table1 and Table2) whereas at least five trials for each period of exercise should be taken. Most significantly, the multiple trials of the experiment cannot be ignored in order to gain more accurate results. Also, to be able to compare the effect of different periods of exercises on CO2 production, more time periods are needed. For example, three and four minutes of exercises’ effects could be measured to get a better graph to see the overall CO2 produced for each period of exercise.
There is an increase in the value of CO2 produced while the time period of the exercise increases. The biggest amount of CO2 was released after two minutes of exercise. Therefore, the result of this experiment supports part of the hypothesis, which states that if the duration of the exercise is increased, the energy requirement of a person will increase, therefore, the rate of the reaction will be increased and CO2 will be produced more.
Aerobic Respiration. Campbell, Neil A., Biology: Concepts and Connections, Pearson: San Francisco, 2006
Answer. “What effect would exercise have on the amount of carbon dioxide made in respiration?” Oct 28, 2012:
Formula. “How do you calculate uncertainty when taking an average of something?” Nov 11, 2012:
Live Strong. DiMenna, Fred. “What Effect does Exercise Have on the Amount of Carbon Dioxide Released by the Blood?” Oct 28, Aug 23, 2011: