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4. Identify the dependent variable in the lung volume bag investigation. What units would it be measured in? 5. Identify the independent variable in the investigation. What units would it be measured in? 6. One student suggested that they should all take a deep breath in before measuring their lung volume. Suggest two other factors that the students would need to control.
Unravelling the data
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Data was collected from some adult male students at a university to investigate the link between height and lung volume – the results are shown in Figure 1.2.14b. 7. Describe what this data shows about the link between height and lung volume. 8. From further investigation, the scientists found out that one of the men is an outstanding athlete. How tall is this man?
Did you know . . . ? Spanish cyclist (and five times Tour de France winner) Miguel Indurain had lungs so big that they displaced his stomach, leading to a trademark paunch. His lung capacity was 8 litres when he was at his fittest.
9. Suggest why this data may be more reliable than the data collected by the school students. 12
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Lung volume (litres)
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6 FIGURE 1.2.14c: Miguel Indurain 4
Key vocabulary 2
vital capacity independent variable 0 100
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FIGURE 1.2.14b: Lung volume and height investigation.
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dependent variable control variable
SEARCH: measuring vital capacity
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