Name: ______Date: ______Class: ______
Just Breathe
Introduction
Who do you think has a greater lung volume: males or females? In this lab, we will use a lung measuring device called a spirometer to measure the volume of the lungs in liters and use this data to test a hypothesis that you write. This data is very relevant to numerous diseases. Suppose that someone has asthma, or a collapsed lung; knowing what the average person of that age and gender has for a lung volume would be helpful in diagnosing and treating these disorders.
Start by outlining your experiment below.
1. What is the independent variable?
2. What is the dependent variable?
3. What would be a null hypothesis for this experiment?
Procedure for using Lung Volume Device1. Sterilize the end of the air displacement instrument.
2. Take a couple of deep breaths, then breathe out all of the air in your lungs and then take in the BIGGEST breath you can. Blow out all of this air into the air displacement instrument until you can’t exhale anymore. Don’t cheat! You get one breath.
3. Take two measurements. Use the larger volume that is found.
4. Now, come up with an independent variable to investigate. Make sure that your independent variable is quantitative, and thus you are able to represent it on a line graph. Ok it with the teacher.
§ For example, if you want to investigate athletics, a “yes I play sports” or “no I don’t play sports” isn’t a quantitative measurement. However, the number of years that a person has played sports is!
5. The dependent variable will be lung volume.
6. Collect data from your classmates and put it into the data table provided.
Above Left: a wet spirometer. Above Right: hospitals often use a digital version of a spirometer
Your personal data:
Your name: ______
Trial / Lung Volume (in liters) / Highest lung volume measured:1
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Class Data: Measure 10 males and 10 females
Name of student / State the Independent Variable: / State the Dependent Variable:1
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1. Calculate the average and standard deviation for your two groups.
2. Find the p-value by doing a t-test. What does the p-value tell us?
3. Make a bar graph to show the averages of your data. Be sure to include all of the important parts of a graph, such as a title, and all of the labels. Use error bars to show the standard deviation of these averages on your graph.
Post-Lab Questions
Answer the following questions in complete sentences.
1. What were sources of scientific error that may have skewed the data in this experiment? What are some ways that we could make this experiment more accurate?
2. What happens in the lungs? What is the purpose of breathing? Why is your lung volume even important?
3. Most of the time, a person doesn’t inspire or expire all of the air in their lungs. Tidal volume is defined as the volume of air that is inspired and expired while at rest. Do you think that the people we sampled have significantly differing tidal volumes? Why or why not?
4. Consider the effect that smoking tobacco would have on lung volume.
a. On the graph to the right, draw a line for how you think lung volume would relate to number of cigarettes smoked per day.
b. Explain in a few complete sentences why you made the line the way you did.
5. Consider age and lung volume.
a. On the graph to the right, draw a line for how you think lung volume would relate to age.
b. Explain in a few complete sentences why you made the line the way you did.
M. R. Lawton 2015